|
Home > Archive > Alternative Power sources > January 2006 > Newbie - Connection question
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
Newbie - Connection question
|
|
|
| Apologies if my question seems very basic.
I want to create a small off-grid system to provide lighting and
occasional power to a small stable block. To this end I have purchased
the following:
4 x 110Ahr leisure batteries
1 x 80W solar pannel (which came with a small 8amp charge controller)
1 x 2Kw (modified sine wave) inverter
I have assumed that I can connect the batteries in parallel, and have
done this in what may seem to be an odd way by connecting each one
separately to a common point, i.e. I have four leads for each of +ve
and -ve comming to one junction (for each pole). From that point I have
leads running to the inverter.
I did this so that I could easily remove any one of the batteries for
off-site charging if required, leaving the rest to power the system.
I have also assumed that I can simply connect the appropriate terminals
from the charge controller to the common junctions and the solar panel
will charge all the batteries together.
The charge controller does have a couple of terminals that are supposed
to go to the load (i.e. the inverter) but I don't want to use them as I
will be pushing far too much current through such a small device.
I have read some messages in this group that have worried me as I am
now concerned that connecting my four batteries together will cause
them to either overheat or be somehow not correctly balanced.
Am I doing anything wrong in the set-up I have proposed. By the way I
have not yet actually connected it all together, but I have all the
kit.
| |
|
| In the interest of no responses yet, I'll offer you what I know
and let those with actual experience chime in when they see your
message.
Batteries, I believe, MUST be ISOLATED from each other!! So far,
assuming the batteries are all in about the same condition, you
probably haven't had any damage yet, but I'm pretty sure it's
coming!
Something as simple as a diode can be used to isolate the
batteries. The "trick" is to NEVER let one battery be able to
supply power into another battery. Depending on the
circumstances, not having that isolation could result in anything
from a short battery life to an explosion that might be pretty
but also might be pretty dangerous.
When you tie two batteries together in parallel, they will try
to instantaneously become one battery. If one battery is, say,
12.5 volts, and the other battery is, say, 12.0V, they will
source/sink current until they are both the exact same voltage.
The amount of amperage that will generate will depend on a lot
of things, but mainly the battery's internal resistances. For a
half volt difference, you may or may not notice anything going
on.
Now, let's draw some power off them. They aren't likely to be
perfectly identical, so one will start to "drain" at a different
level than the other. One battery will supply current at a
higher rate than the other. But when the load drops, or is
removed, now the two batteries will again try to come to
equilibrium, which means they will attempt to instantaneously
move to identical charges. Now, THAT situation could be many,
many amps, in the extreme limited only the the very low battery
internal resistances and the wiring resistances. In the extreme
it could be like shorting one of the batteries and super-charging
the other way above its safe charge current. And bloomo;
something has to give. With luck, it'll be a shortened battery
life until it becomes simply a resistor. Without luck, you have
sparks, melting, possible implosion/explosions and lots of acid
flying around in addition to the heat.
I would disconnect the batteries ASAP until you can learn more
about how to isolate them from each other and get a safet setup
in there.
And yes, I know it's possible to parallel batteries in some
battery operated equipment, but that's a different game with
entirely different possibilities in most cases. That's why most
things you see have series battery arrangements vs parallel -
much longer battery lifetimes.
HTH, and I'm sure someone with actual experience will be along
soon.
Pop
"Tim" <tim_usnet@btinternet.com> wrote in message
news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...
: Apologies if my question seems very basic.
:
: I want to create a small off-grid system to provide lighting
and
: occasional power to a small stable block. To this end I have
purchased
: the following:
: 4 x 110Ahr leisure batteries
: 1 x 80W solar pannel (which came with a small 8amp charge
controller)
: 1 x 2Kw (modified sine wave) inverter
:
: I have assumed that I can connect the batteries in parallel,
and have
: done this in what may seem to be an odd way by connecting each
one
: separately to a common point, i.e. I have four leads for each
of +ve
: and -ve comming to one junction (for each pole). From that
point I have
: leads running to the inverter.
:
: I did this so that I could easily remove any one of the
batteries for
: off-site charging if required, leaving the rest to power the
system.
:
: I have also assumed that I can simply connect the appropriate
terminals
: from the charge controller to the common junctions and the
solar panel
: will charge all the batteries together.
:
: The charge controller does have a couple of terminals that are
supposed
: to go to the load (i.e. the inverter) but I don't want to use
them as I
: will be pushing far too much current through such a small
device.
:
: I have read some messages in this group that have worried me as
I am
: now concerned that connecting my four batteries together will
cause
: them to either overheat or be somehow not correctly balanced.
:
: Am I doing anything wrong in the set-up I have proposed. By the
way I
: have not yet actually connected it all together, but I have all
the
: kit.
:
| |
| Vaughn 2006-01-13, 9:21 pm |
|
"Tim" <tim_usnet@btinternet.com> wrote in message
news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...
> Am I doing anything wrong in the set-up I have proposed. By the way I
> have not yet actually connected it all together, but I have all the
> kit.
You have just described the setup I have been using without trouble for the
last several years. As long as the batteries are matched, all should be OK. I
have even done pretty well with not-so-matched batteries.
You may want to consider forgetting the inverter and going to 12 volt
fluorescent lighting.
Vaughn
| |
| Steve Spence 2006-01-13, 10:21 pm |
| Pop wrote:
> In the interest of no responses yet, I'll offer you what I know
> and let those with actual experience chime in when they see your
> message.
>
> Batteries, I believe, MUST be ISOLATED from each other!! So far,
> assuming the batteries are all in about the same condition, you
> probably haven't had any damage yet, but I'm pretty sure it's
> coming!
> Something as simple as a diode can be used to isolate the
> batteries. The "trick" is to NEVER let one battery be able to
> supply power into another battery. Depending on the
> circumstances, not having that isolation could result in anything
> from a short battery life to an explosion that might be pretty
> but also might be pretty dangerous.
No No No. When using 12 volt batts in a 12v pack, all the positives are
connected to gether, and all the negatives are connected together. There
are no diodes. All the batts need to be identical in type and life.
Your charger wants to see them as one big battery.
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
| Steve Spence 2006-01-13, 10:21 pm |
| Tim wrote:
> Apologies if my question seems very basic.
>
> I want to create a small off-grid system to provide lighting and
> occasional power to a small stable block. To this end I have purchased
> the following:
> 4 x 110Ahr leisure batteries
We have Six 6v 225 ah batts in a 2 x 3 array for 12v, 675ah
You have a 440ah pack, but only 220ah useable.
> 1 x 80W solar pannel (which came with a small 8amp charge controller)
We have a 90 watt array with a 30amp controller. Room for growth.
> 1 x 2Kw (modified sine wave) inverter
A 2kw inverter can suck those batteries dry in just over an hour at full
load. We have a 2.5kw MSW inverter.
>
> I have assumed that I can connect the batteries in parallel, and have
> done this in what may seem to be an odd way by connecting each one
> separately to a common point, i.e. I have four leads for each of +ve
> and -ve comming to one junction (for each pole). From that point I have
> leads running to the inverter.
This is correct.
>
> I did this so that I could easily remove any one of the batteries for
> off-site charging if required, leaving the rest to power the system.
>
> I have also assumed that I can simply connect the appropriate terminals
> from the charge controller to the common junctions and the solar panel
> will charge all the batteries together.
correct.
>
> The charge controller does have a couple of terminals that are supposed
> to go to the load (i.e. the inverter) but I don't want to use them as I
> will be pushing far too much current through such a small device.
the load is the batteries.
>
> I have read some messages in this group that have worried me as I am
> now concerned that connecting my four batteries together will cause
> them to either overheat or be somehow not correctly balanced.
no, you have correctly connected them.
>
> Am I doing anything wrong in the set-up I have proposed. By the way I
> have not yet actually connected it all together, but I have all the
> kit.
>
sounds like it's all good.
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
| SolarFlaire 2006-01-13, 11:21 pm |
| I have to agree with Steve on this one. While no
personal experience with doing this it is done on a
quite popular basis. Ever see a diode explode? I have
and you want your face and eyes covered. Little
firecrackers they are. Forget the diodes, too much loss
and resistance.
The start topology is a great idea although probably
not necessary. It may help the sharing of charge and
discharge between the cells. regular equalizing also
helps. The weaker clucters will get brought up to the
level of the stronger ones, avoiding cross charging (if
such a thing even exists)
If the fear mongers really get you down, you insert
large fuses in each lead to the star point. The fuses
will off a few milliohms of isolation between the
clusters and also provide some protection in the rare
case of a shorted cell.
Remember, all the square inches of plate material in a
cell are in parallel already. You are just separating
some of the surface area into different boxes.
"Steve Spence" <sspence@green-trust.org> wrote in
message news:43c84f30_1@newsfeed.slurp.net...
> No No No. When using 12 volt batts in a 12v pack, all
the positives are
> connected to gether, and all the negatives are
connected together. There
> are no diodes. All the batts need to be identical in
type and life.
>
> Your charger wants to see them as one big battery.
>
>
>
>
> --
> Steve Spence
> Dir., Green Trust, http://www.green-trust.org
> Contributing Editor, http://www.off-grid.net
> http://www.rebelwolf.com/essn.html
| |
| Windsun 2006-01-14, 4:21 am |
| That is exactly what they are SUPPOSED to do.
-------------------------------------------------------------------------
Free Solar Discussion Forum: http://www.wind-sun.com/smf/index.php
-------------------------------------------------------------------------
"Pop" <nobody@devnull.spamcop.net> wrote in message
news:aZWxf.168$Bn4.96@trndny08...
> When you tie two batteries together in parallel, they will try
> to instantaneously become one battery.....
| |
|
| Thank you all for your replies, I am much happier now.
Just one small point in your reply Steve, The small charge controller I
got (free with the solar panel, which is why I reckon it is very
basic), has three sets of terminals. One for the solar array, one for
the battery and one for the load. The controller is designed to switch
off the load if the battery gets too discharged. However it allows a
max load current of 8amp which is way too small. Anyhow the inverter
itself will not allow the battery to become discharged so I don't need
this protection.
Also I purchased the four batteries at the same time, all of the same
design, so they should be pretty well matched.
Once again thanks for all the help.
Steve Spence wrote:
> Tim wrote:
>
> We have Six 6v 225 ah batts in a 2 x 3 array for 12v, 675ah
>
> You have a 440ah pack, but only 220ah useable.
>
>
> We have a 90 watt array with a 30amp controller. Room for growth.
>
>
> A 2kw inverter can suck those batteries dry in just over an hour at full
> load. We have a 2.5kw MSW inverter.
>
>
> This is correct.
>
>
> correct.
>
>
> the load is the batteries.
>
>
> no, you have correctly connected them.
>
>
> sounds like it's all good.
>
> --
> Steve Spence
> Dir., Green Trust, http://www.green-trust.org
> Contributing Editor, http://www.off-grid.net
> http://www.rebelwolf.com/essn.html
| |
|
| Apologies Steve, I just noticed one more comment in your reply to me
that I would like you to clarify. You have said that my battery pack of
four 110Ah batteries only gives a usable 220Ah. Is this because that is
all that is available, if so why, or is it because you should allow a
50% headroon to stop the batteries discharging too far?
Thanks again
Tim Horscroft
| |
| George Ghio 2006-01-14, 8:21 am |
|
Steve Spence wrote:
> Tim wrote:
>
>
>
> We have Six 6v 225 ah batts in a 2 x 3 array for 12v, 675ah
>
> You have a 440ah pack, but only 220ah useable.
Why would you say that Steve.
4x110=440 - Yes
220 - ?
>
Less than half the panels needed to charge 440Ah - ROT; 1 Panel for
every 100AH of battery capacity[color=darkred]
>
>
> We have a 90 watt array with a 30amp controller. Room for growth.
>
>
>
> A 2kw inverter can suck those batteries dry in just over an hour at full
> load. We have a 2.5kw MSW inverter.
>
>
>
> This is correct.
Yes, all connecting cables should ideally be the same length
>
>
>
> correct.
>
>
>
> the load is the batteries.
Incorrect. Load is load. i.e. something to be run from the batteries. In
the interest of the life of your charge controller do not connect the
inverter to the load terminals.
To be correct, What are the terminals on the reg marked as?
>
>
>
> no, you have correctly connected them.
Yes
>
>
> sounds like it's all good.
Yes
>
| |
| Steve Spence 2006-01-14, 9:21 am |
| Tim wrote:
> Apologies Steve, I just noticed one more comment in your reply to me
> that I would like you to clarify. You have said that my battery pack of
> four 110Ah batteries only gives a usable 220Ah. Is this because that is
> all that is available, if so why, or is it because you should allow a
> 50% headroon to stop the batteries discharging too far?
>
> Thanks again
>
> Tim Horscroft
>
To allow for 50% maximum discharge.
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
| daestrom 2006-01-14, 11:21 am |
|
"Tim" <tim_usnet@btinternet.com> wrote in message
news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...
> Apologies if my question seems very basic.
>
> I want to create a small off-grid system to provide lighting and
> occasional power to a small stable block. To this end I have purchased
> the following:
> 4 x 110Ahr leisure batteries
> 1 x 80W solar pannel (which came with a small 8amp charge controller)
> 1 x 2Kw (modified sine wave) inverter
>
> I have assumed that I can connect the batteries in parallel, and have
> done this in what may seem to be an odd way by connecting each one
> separately to a common point, i.e. I have four leads for each of +ve
> and -ve comming to one junction (for each pole). From that point I have
> leads running to the inverter.
>
> I did this so that I could easily remove any one of the batteries for
> off-site charging if required, leaving the rest to power the system.
>
> I have also assumed that I can simply connect the appropriate terminals
> from the charge controller to the common junctions and the solar panel
> will charge all the batteries together.
>
> The charge controller does have a couple of terminals that are supposed
> to go to the load (i.e. the inverter) but I don't want to use them as I
> will be pushing far too much current through such a small device.
>
> I have read some messages in this group that have worried me as I am
> now concerned that connecting my four batteries together will cause
> them to either overheat or be somehow not correctly balanced.
>
> Am I doing anything wrong in the set-up I have proposed. By the way I
> have not yet actually connected it all together, but I have all the
> kit.
>
Some thoughts....
With 4x110ah, you have a total of 440 ah. But it's not a good idea to
routinely run them all the way dead (100% depth of discharge), so for
planning purposes, you should plan on only using about half that on a
routine basis (i.e. plan on only 220 ah usage).
With an 80W panel, at about 14 volts charging voltage, you are only going to
get a bit over 5 amps. Split perfectly between the four batteries, that
means about 1 amp per battery. This isn't much more than a trickle charge
rate. It would take on the order of 44 hours of sunshine to recharge from
the 50% discharge point (more than 88 hours from fully discharged). You may
want to get more panels sometime soon. Or you'll have to charge the
batteries from some other source often.
As far as putting batteries in parallel, you'll hear all sorts of
information on that. In general, it is not the *best* solution. If the
batteries are identical make/model/age, and they all receive identical care,
then you can do it and get away with it for a while. But sooner or later,
one or more cell, in one or more of the batteries will start to degrade.
And then that battery will charge differently than the others, and they
start to diverge and no longer operate well together and 'share' the
load/charge as evenly. Things go down hill after that.
If one cell *does* develop a short, then the other three batteries in your
setup will supply reverse current to the bad battery trying to 'charge' it.
The bad guy can overheat and boil down. So if you notice that one battery
needs water more than others, watch out.
How often do you plan on checking the system? Will you be there daily, or
is this something you want to leave for a few months at a time? If the
later, you might want some additional circuit protection.
It would be a good idea if you could put an appropriately sized DC fuse
between each battery and the common tie point. Size it for the expected
amount of load you will be supplying, and then if an overload occurs, or
three 'good' batteries start overcharging one 'bad' one, the 'bad' batteries
fuse will blow and isolate it before you have a catastrophic failure.
daestrom
| |
|
| Well, from the look of the other responses, I guess I stand
corrected, but ... I still think it's an unsafe setup from both a
personnel and an equipment viewpoint. I'm not saying it WILL
happen, but I am saying it MAY happen, and over time it's very
possible. Here's some food for thought, and also BTW, I'm NOT
passing judgement on any of the opposing posts because to a
degree, they are all correct also, but ... just not completely.
Food for thought:
-- A batch of batteries all from the same manufacturing lot will
likely be well matched.
-- From different lots, that's not so likely. One weaker
battery in the lot will always use the other batteries to
maintain its charge, as opposed to all of them giving their power
to the load.
-- Battery failure curves and timing is notoroiously
unpredictable. Sooner or later one or more batteries will begin
to "feed from" the others.
-- Battery replacement will need to be done in full group at
once. If one battery gives out over only half or less of its
expected life, replacing that one defective battery will result
in that battery immediately having to "help" the rest of the
batteries to rise to its potential storage capacity. To be sure
all batteries are supplying power to the load, they all have to
be changed at the same time.
Constant, daily attention and inspection of the battery lot would
be necessary to insure a modicum of safety and efficiency.
Someone mentioned fuses: I assumed each battery would be fused,
which looks like it may have been a serious oversight on my part.
IMO, fuses would be a must.
Diode isolation is simple, cheap and pretty much guarantees,
within reason, that:
-- Catastrophic currents can never go INTO any battery from
another;
-- The batteries only supply power to the load, not to each
other, resulting in a loss of efficiency.
Depending on the types of diodes used, the voltage losses will
range from 0.15V max up to 0.9V or so with germaniums. 0.1V
drops are nominal for the better material diodes. Both are
neglible losses when considering the efficiencies likely without
them, it just dpeends on your pocket book and desire to approach
nominal.
Someone mentioned blowing the diodes: Not if they're specced
right. Diodes have a reliability rating far in excess of
batteries. Any blasted-open diode can be accurately assumed to
have saved the day in more expensive components.
Combined with fuses you have a pretty reliable system that
should last for years. You'll get the best output, not go down
should one battery die, and be able to replace just one battery
at a time instead of the entire group, knowing it won't degrade
efficiency.
Someone mentioned fear-mongering, and if that's what you consider
this, then so be it. It sort of depends on whether you want a
fix or repair daily or the best reliability and efficiency at a
reasonable cost/watt.
So, yes, you can just parallel them and it'll work. But it
can be made to work a lot better and for less money in the long
run.
If you wish to respond to this, that's fine: I'll discuss, but I
won't debate or argue; no future in that.
HTH,
Pop
"Pop" <nobody@devnull.spamcop.net> wrote in message
news:aZWxf.168$Bn4.96@trndny08...
: In the interest of no responses yet, I'll offer you what I know
: and let those with actual experience chime in when they see
your
: message.
:
: Batteries, I believe, MUST be ISOLATED from each other!! So
far,
: assuming the batteries are all in about the same condition, you
: probably haven't had any damage yet, but I'm pretty sure it's
: coming!
: Something as simple as a diode can be used to isolate the
: batteries. The "trick" is to NEVER let one battery be able to
: supply power into another battery. Depending on the
: circumstances, not having that isolation could result in
anything
: from a short battery life to an explosion that might be pretty
: but also might be pretty dangerous.
:
: When you tie two batteries together in parallel, they will
try
: to instantaneously become one battery. If one battery is, say,
: 12.5 volts, and the other battery is, say, 12.0V, they will
: source/sink current until they are both the exact same voltage.
: The amount of amperage that will generate will depend on a
lot
: of things, but mainly the battery's internal resistances. For
a
: half volt difference, you may or may not notice anything going
: on.
: Now, let's draw some power off them. They aren't likely to be
: perfectly identical, so one will start to "drain" at a
different
: level than the other. One battery will supply current at a
: higher rate than the other. But when the load drops, or is
: removed, now the two batteries will again try to come to
: equilibrium, which means they will attempt to instantaneously
: move to identical charges. Now, THAT situation could be many,
: many amps, in the extreme limited only the the very low battery
: internal resistances and the wiring resistances. In the
extreme
: it could be like shorting one of the batteries and
super-charging
: the other way above its safe charge current. And bloomo;
: something has to give. With luck, it'll be a shortened battery
: life until it becomes simply a resistor. Without luck, you
have
: sparks, melting, possible implosion/explosions and lots of acid
: flying around in addition to the heat.
:
: I would disconnect the batteries ASAP until you can learn more
: about how to isolate them from each other and get a safet setup
: in there.
: And yes, I know it's possible to parallel batteries in some
: battery operated equipment, but that's a different game with
: entirely different possibilities in most cases. That's why
most
: things you see have series battery arrangements vs parallel -
: much longer battery lifetimes.
:
: HTH, and I'm sure someone with actual experience will be along
: soon.
:
: Pop
:
:
:
: "Tim" <tim_usnet@btinternet.com> wrote in message
: news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...
:: Apologies if my question seems very basic.
::
:: I want to create a small off-grid system to provide lighting
: and
:: occasional power to a small stable block. To this end I have
: purchased
:: the following:
:: 4 x 110Ahr leisure batteries
:: 1 x 80W solar pannel (which came with a small 8amp charge
: controller)
:: 1 x 2Kw (modified sine wave) inverter
::
:: I have assumed that I can connect the batteries in parallel,
: and have
:: done this in what may seem to be an odd way by connecting each
: one
:: separately to a common point, i.e. I have four leads for each
: of +ve
:: and -ve comming to one junction (for each pole). From that
: point I have
:: leads running to the inverter.
::
:: I did this so that I could easily remove any one of the
: batteries for
:: off-site charging if required, leaving the rest to power the
: system.
::
:: I have also assumed that I can simply connect the appropriate
: terminals
:: from the charge controller to the common junctions and the
: solar panel
:: will charge all the batteries together.
::
:: The charge controller does have a couple of terminals that are
: supposed
:: to go to the load (i.e. the inverter) but I don't want to use
: them as I
:: will be pushing far too much current through such a small
: device.
::
:: I have read some messages in this group that have worried me
as
: I am
:: now concerned that connecting my four batteries together will
: cause
:: them to either overheat or be somehow not correctly balanced.
::
:: Am I doing anything wrong in the set-up I have proposed. By
the
: way I
:: have not yet actually connected it all together, but I have
all
: the
:: kit.
::
:
:
| |
| Derek Broughton 2006-01-14, 12:21 pm |
| Steve Spence wrote:
> Tim wrote:
>
> correct.
Not a good idea by anything I've read. So you pull one battery, fully
charge it, and then put it back in parallel with the other three - don't
you have a serious fire hazard?
>
> the load is the batteries.
Those little CCs usually have terminals for PV, battery, and load. But
Tim's right that he doesn't want to be powering his inverter through there.
One hopes the inverter has it's own low-voltage cutoff.
--
derek
| |
| Steve Spence 2006-01-14, 1:21 pm |
| Derek Broughton wrote:
> Steve Spence wrote:
>
>
>
>
>
>
> Not a good idea by anything I've read. So you pull one battery, fully
> charge it, and then put it back in parallel with the other three - don't
> you have a serious fire hazard?
>
>
>
>
> Those little CCs usually have terminals for PV, battery, and load. But
> Tim's right that he doesn't want to be powering his inverter through there.
> One hopes the inverter has it's own low-voltage cutoff.
I've haven't had the opportunity to play with that type of charge
controller. our have a pv in and battery bank out. Inverter connects to
battery bank through a big fuse, with much bigger cables than a charge
controller deals with.
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
| Harry Chickpea 2006-01-14, 1:21 pm |
| "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote:
>With an 80W panel, at about 14 volts charging voltage, you are only going to
>get a bit over 5 amps. Split perfectly between the four batteries, that
>means about 1 amp per battery. This isn't much more than a trickle charge
>rate. It would take on the order of 44 hours of sunshine to recharge from
>the 50% discharge point (more than 88 hours from fully discharged). You may
>want to get more panels sometime soon. Or you'll have to charge the
>batteries from some other source often.
The 50% discharge max that Steve mentioned and the rating of solar
panels are two of the most mis-understood issues for newbies. Unless
you live in the high desert, the actual average charging capacity of
solar is a lot less than one might expect. The panels are rated
correctly, there is no intentional deception, but you have to have a
sunny day to get the advertised wattage, and the sun only provides
usable intense light for less than half the day at best. Pushing
through a wire that is longer than ideal, I measure that my quadlam
puts out about 70 watts mid-day on a sunny day. On an average cloudy
day, that figure can be less than 20 watts.
I think Daestrom is being optimistic in even suggesting recharging
from a 50% discharge. In the real world, with cloudy days,
intermittant draws on the system, recharging requiring from 105% or
more of the energy extracted, derating from temperature differences,
etc., this would be a process that could easily take two weeks. In
some locations, like the mountains of Vermont, where the sun may not
shine more than a few days in a month, it could take most of the
winter.
Without full and regular charging of your batteries, and a regular
equalization charge, batteries will get sulfated an die a very early
death. Unless the usage is very small, or you add a secondary method
of charging, this system has the potential to kill batteries.
Get a battery tester to test the specific gravity of the individual
cells in your bank. Measure the new cells when fully charged as a
reference (and to convince yourself that this is what they should
read) and then write the readings down and re-measure at least every
week at first. You can also use a voltmeter to check the
state-of-charge, but voltages vary based on a number of factors and
are less trustworthy until you understand and compensate for all of
them.
Plan on getting the SG back up to full for a day at least every week
or two. The longer batteries sit partially discharged, the more the
sulphation can become a problem.
With a single 80 watt panel, I'd figure on using a couple of CFs in
the evening and maybe a couple of small loads. On a cloudy mid-winter
day, a panel like that might only give you enough daily output to run
a 100 watt lamp for an hour. Splurge a little on sunny days. Like
Mr. McCawber says about income and expenses, you can't take more out
than you put in and expect to be happy.
| |
| Derek Broughton 2006-01-14, 5:21 pm |
| Steve Spence wrote:
> Derek Broughton wrote:
>
> I've haven't had the opportunity to play with that type of charge
> controller. our have a pv in and battery bank out. Inverter connects to
> battery bank through a big fuse, with much bigger cables than a charge
> controller deals with.
I have one attached to a 15W panel, a tiny battery and a 12V fan for moving
air through a solar heater. This one really only has a battery to even out
the voltage as it just runs in the daytime. I have a second, larger, one
connected to 100W PV and a battery system for my DC well pump. Neither one
of these ever draws more than the rated current for the charge controller.
The third system is the AC system, and that one has the inverter directly
connected to the batteries. Both the Outback inverter I use now and the
cheap MSW inverter I used before that had their own low voltage cutoff.
--
derek
| |
| phatty mo 2006-01-14, 8:21 pm |
| Pop wrote:
> Well, from the look of the other responses, I guess I stand
> corrected, but ... I still think it's an unsafe setup from both a
> personnel and an equipment viewpoint. I'm not saying it WILL
> happen, but I am saying it MAY happen, and over time it's very
> possible. Here's some food for thought, and also BTW, I'm NOT
> passing judgement on any of the opposing posts because to a
> degree, they are all correct also, but ... just not completely.
>
> Food for thought:
> -- A batch of batteries all from the same manufacturing lot will
> likely be well matched.
> -- From different lots, that's not so likely. One weaker
> battery in the lot will always use the other batteries to
> maintain its charge, as opposed to all of them giving their power
> to the load.
> -- Battery failure curves and timing is notoroiously
> unpredictable. Sooner or later one or more batteries will begin
> to "feed from" the others.
> -- Battery replacement will need to be done in full group at
> once. If one battery gives out over only half or less of its
> expected life, replacing that one defective battery will result
> in that battery immediately having to "help" the rest of the
> batteries to rise to its potential storage capacity. To be sure
> all batteries are supplying power to the load, they all have to
> be changed at the same time.
>
> Constant, daily attention and inspection of the battery lot would
> be necessary to insure a modicum of safety and efficiency.
>
> Someone mentioned fuses: I assumed each battery would be fused,
> which looks like it may have been a serious oversight on my part.
> IMO, fuses would be a must.
>
> Diode isolation is simple, cheap and pretty much guarantees,
> within reason, that:
> -- Catastrophic currents can never go INTO any battery from
> another;
> -- The batteries only supply power to the load, not to each
> other, resulting in a loss of efficiency.
This is exactly why I used diodes in my (small) setup.
I have 3 car batteries,and a collection of smaller SLA's all different
ages,type,sizes,etc. all in parallel with diode isolation.
I've already had one battery fail,and draw excess current.
The battery bank was fine,slightly under charged,because the bad battery
was hogging all the charge current.
I actually noticed because the voltage seemed a bit low,considering it
was a nice sunny day,and the batteries should be charging.
I got out the DMM,and started measuring each batteries voltage,and
quickly found the culprit...I unplugged it,and instantly the bank was
back to normal,and NONE of the other batteries were discharged! (just a
bit low)
That scenario was the *exact* reason I used diodes.
That one battery could have deeply discharged the rest of the
batteries,and killed the whole bank,at the best..
Worst case would be a boiling/exploding battery,AND a bank of dead
worthless batteries.
Use schottky or fast recovery diodes (lower voltage drop) for less loss.
I think the diodes I used on the car batteries are '122NQ030' parts
(120Amp,low Voltage drop. ~0.4V,I think.)
The small loss of efficiency is worth the peace of mind,IMO.
> Depending on the types of diodes used, the voltage losses will
> range from 0.15V max up to 0.9V or so with germaniums. 0.1V
> drops are nominal for the better material diodes. Both are
> neglible losses when considering the efficiencies likely without
> them, it just dpeends on your pocket book and desire to approach
> nominal.
>
> Someone mentioned blowing the diodes: Not if they're specced
> right. Diodes have a reliability rating far in excess of
> batteries. Any blasted-open diode can be accurately assumed to
> have saved the day in more expensive components.
> Combined with fuses you have a pretty reliable system that
> should last for years. You'll get the best output, not go down
> should one battery die, and be able to replace just one battery
> at a time instead of the entire group, knowing it won't degrade
> efficiency.
>
> Someone mentioned fear-mongering, and if that's what you consider
> this, then so be it. It sort of depends on whether you want a
> fix or repair daily or the best reliability and efficiency at a
> reasonable cost/watt.
> So, yes, you can just parallel them and it'll work. But it
> can be made to work a lot better and for less money in the long
> run.
>
> If you wish to respond to this, that's fine: I'll discuss, but I
> won't debate or argue; no future in that.
>
> HTH,
>
> Pop
>
>
>
>
>
> "Pop" <nobody@devnull.spamcop.net> wrote in message
> news:aZWxf.168$Bn4.96@trndny08...
> : In the interest of no responses yet, I'll offer you what I know
> : and let those with actual experience chime in when they see
> your
> : message.
> :
> : Batteries, I believe, MUST be ISOLATED from each other!! So
> far,
> : assuming the batteries are all in about the same condition, you
> : probably haven't had any damage yet, but I'm pretty sure it's
> : coming!
> : Something as simple as a diode can be used to isolate the
> : batteries. The "trick" is to NEVER let one battery be able to
> : supply power into another battery. Depending on the
> : circumstances, not having that isolation could result in
> anything
> : from a short battery life to an explosion that might be pretty
> : but also might be pretty dangerous.
> :
> : When you tie two batteries together in parallel, they will
> try
> : to instantaneously become one battery. If one battery is, say,
> : 12.5 volts, and the other battery is, say, 12.0V, they will
> : source/sink current until they are both the exact same voltage.
> : The amount of amperage that will generate will depend on a
> lot
> : of things, but mainly the battery's internal resistances. For
> a
> : half volt difference, you may or may not notice anything going
> : on.
> : Now, let's draw some power off them. They aren't likely to be
> : perfectly identical, so one will start to "drain" at a
> different
> : level than the other. One battery will supply current at a
> : higher rate than the other. But when the load drops, or is
> : removed, now the two batteries will again try to come to
> : equilibrium, which means they will attempt to instantaneously
> : move to identical charges. Now, THAT situation could be many,
> : many amps, in the extreme limited only the the very low battery
> : internal resistances and the wiring resistances. In the
> extreme
> : it could be like shorting one of the batteries and
> super-charging
> : the other way above its safe charge current. And bloomo;
> : something has to give. With luck, it'll be a shortened battery
> : life until it becomes simply a resistor. Without luck, you
> have
> : sparks, melting, possible implosion/explosions and lots of acid
> : flying around in addition to the heat.
> :
> : I would disconnect the batteries ASAP until you can learn more
> : about how to isolate them from each other and get a safet setup
> : in there.
> : And yes, I know it's possible to parallel batteries in some
> : battery operated equipment, but that's a different game with
> : entirely different possibilities in most cases. That's why
> most
> : things you see have series battery arrangements vs parallel -
> : much longer battery lifetimes.
> :
> : HTH, and I'm sure someone with actual experience will be along
> : soon.
> :
> : Pop
> :
> :
> :
> : "Tim" <tim_usnet@btinternet.com> wrote in message
> : news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...
> :: Apologies if my question seems very basic.
> ::
> :: I want to create a small off-grid system to provide lighting
> : and
> :: occasional power to a small stable block. To this end I have
> : purchased
> :: the following:
> :: 4 x 110Ahr leisure batteries
> :: 1 x 80W solar pannel (which came with a small 8amp charge
> : controller)
> :: 1 x 2Kw (modified sine wave) inverter
> ::
> :: I have assumed that I can connect the batteries in parallel,
> : and have
> :: done this in what may seem to be an odd way by connecting each
> : one
> :: separately to a common point, i.e. I have four leads for each
> : of +ve
> :: and -ve comming to one junction (for each pole). From that
> : point I have
> :: leads running to the inverter.
> ::
> :: I did this so that I could easily remove any one of the
> : batteries for
> :: off-site charging if required, leaving the rest to power the
> : system.
> ::
> :: I have also assumed that I can simply connect the appropriate
> : terminals
> :: from the charge controller to the common junctions and the
> : solar panel
> :: will charge all the batteries together.
> ::
> :: The charge controller does have a couple of terminals that are
> : supposed
> :: to go to the load (i.e. the inverter) but I don't want to use
> : them as I
> :: will be pushing far too much current through such a small
> : device.
> ::
> :: I have read some messages in this group that have worried me
> as
> : I am
> :: now concerned that connecting my four batteries together will
> : cause
> :: them to either overheat or be somehow not correctly balanced.
> ::
> :: Am I doing anything wrong in the set-up I have proposed. By
> the
> : way I
> :: have not yet actually connected it all together, but I have
> all
> : the
> :: kit.
> ::
> :
> :
>
>
| |
| SolarFlaire 2006-01-15, 1:21 am |
| Diodes would not stop one dead cluster from charging
the others in parallel.
"phatty mo" <ptaylor@nospam.com> wrote in message
news:15gyf.42$K84.9438@news.uswest.net...
> Pop wrote:
I stand[color=darkred]
setup from both a[color=darkred]
saying it WILL[color=darkred]
time it's very[color=darkred]
BTW, I'm NOT[color=darkred]
because to a[color=darkred]
completely.[color=darkred]
manufacturing lot will[color=darkred]
weaker[color=darkred]
batteries to[color=darkred]
giving their power[color=darkred]
notoroiously[color=darkred]
batteries will begin[color=darkred]
full group at[color=darkred]
less of its[color=darkred]
will result[color=darkred]
rest of the[color=darkred]
capacity. To be sure[color=darkred]
all have to[color=darkred]
battery lot would[color=darkred]
efficiency.[color=darkred]
would be fused,[color=darkred]
oversight on my part.[color=darkred]
guarantees,[color=darkred]
battery from[color=darkred]
not to each[color=darkred]
>
>
>
> This is exactly why I used diodes in my (small)
setup.
> I have 3 car batteries,and a collection of smaller
SLA's all different
> ages,type,sizes,etc. all in parallel with diode
isolation.
>
> I've already had one battery fail,and draw excess
current.
> The battery bank was fine,slightly under
charged,because the bad battery
> was hogging all the charge current.
> I actually noticed because the voltage seemed a bit
low,considering it
> was a nice sunny day,and the batteries should be
charging.
> I got out the DMM,and started measuring each
batteries voltage,and
> quickly found the culprit...I unplugged it,and
instantly the bank was
> back to normal,and NONE of the other batteries were
discharged! (just a
> bit low)
>
> That scenario was the *exact* reason I used diodes.
> That one battery could have deeply discharged the
rest of the
> batteries,and killed the whole bank,at the best..
> Worst case would be a boiling/exploding battery,AND a
bank of dead
> worthless batteries.
>
> Use schottky or fast recovery diodes (lower voltage
drop) for less loss.
> I think the diodes I used on the car batteries are
'122NQ030' parts
> (120Amp,low Voltage drop. ~0.4V,I think.)
> The small loss of efficiency is worth the peace of
mind,IMO.[color=darkred]
>
>
>
losses will[color=darkred]
germaniums. 0.1V[color=darkred]
Both are[color=darkred]
likely without[color=darkred]
desire to approach[color=darkred]
they're specced[color=darkred]
excess of[color=darkred]
accurately assumed to[color=darkred]
system that[color=darkred]
not go down[color=darkred]
one battery[color=darkred]
won't degrade[color=darkred]
what you consider[color=darkred]
you want a[color=darkred]
efficiency at a[color=darkred]
work. But it[color=darkred]
in the long[color=darkred]
discuss, but I[color=darkred]
you what I know[color=darkred]
when they see[color=darkred]
other!! So[color=darkred]
condition, you[color=darkred]
pretty sure it's[color=darkred]
isolate the[color=darkred]
battery be able to[color=darkred]
the[color=darkred]
result in[color=darkred]
might be pretty[color=darkred]
parallel, they will[color=darkred]
battery is, say,[color=darkred]
they will[color=darkred]
same voltage.[color=darkred]
depend on a[color=darkred]
resistances. For[color=darkred]
anything going[color=darkred]
aren't likely to be[color=darkred]
at a[color=darkred]
current at a[color=darkred]
drops, or is[color=darkred]
come to[color=darkred]
instantaneously[color=darkred]
could be many,[color=darkred]
very low battery[color=darkred]
In the[color=darkred]
and[color=darkred]
bloomo;[color=darkred]
shortened battery[color=darkred]
luck, you[color=darkred]
and lots of acid[color=darkred]
can learn more[color=darkred]
a safet setup[color=darkred]
batteries in some[color=darkred]
different game with[color=darkred]
That's why[color=darkred]
vs parallel -[color=darkred]
will be along[color=darkred]
news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...[color=darkred]
provide lighting[color=darkred]
this end I have[color=darkred]
8amp charge[color=darkred]
in parallel,[color=darkred]
connecting each[color=darkred]
leads for each[color=darkred]
From that[color=darkred]
of the[color=darkred]
to power the[color=darkred]
the appropriate[color=darkred]
junctions and the[color=darkred]
terminals that are[color=darkred]
don't want to use[color=darkred]
such a small[color=darkred]
have worried me[color=darkred]
together will[color=darkred]
correctly balanced.[color=darkred]
proposed. By[color=darkred]
but I have[color=darkred]
| |
| George Ghio 2006-01-15, 3:21 am |
|
Steve Spence wrote:
> Tim wrote:
>
>
> To allow for 50% maximum discharge.
>
>
Tim this is a complete and utter fabrication. You can use as much as 80%
max DOD. I prefer 70% myself. What it comes down to is how often you
discharge your batteries to this level and how long they stay in the low
state of discharge.
During normal operating conditions your daily DOD should be in line with
your chosen days of autonomy and your daily load.
If for example you have a daily load of 2kWh and five days autonomy you
would need a battery bank of around 1400Ah. This would provide 2kWh a
day leaving your batteries ~70% discharged after five days. Your daily
DOD would be 13.5%
Now if you reduce the max DOD to 50% you would need to increase the
battery bank to nearly 2000 Ah.
On the other hand if you are working at a 50% daily DOD you will have
only one and a bit days autonomy, no matter what size your battery bank
| |
| Windsun 2006-01-15, 8:21 am |
| And how, exactly, do you charge these batteries if the diodes are blocking
incoming current?
-------------------------------------------------------------------------
Free Solar Discussion Forum: http://www.wind-sun.com/smf/index.php
-------------------------------------------------------------------------
"Pop" <nobody@devnull.spamcop.net> wrote in message
news:BS8yf.797$Ym3.471@trndny09...
> Diode isolation is simple, cheap and pretty much guarantees,
> within reason, that:
> -- Catastrophic currents can never go INTO any battery from
> another;
> -- The batteries only supply power to the load, not to each
> other, resulting in a loss of efficiency.
| |
| daestrom 2006-01-15, 11:21 am |
|
"Windsun" <wind-sun@earthlink.net> wrote in message
news:WQqyf.2674$Hd4.406@newsread1.news.pas.earthlink.net...
> And how, exactly, do you charge these batteries if the diodes are blocking
> incoming current?
>
It would seem to me you would need two sets of diodes. A 'set' from the
common tie point of the charger allowing charge current into each battery,
and another 'set' from each battery to a common tie point that is *isolated*
from the first, used to supply all the loads.
So when running a load while the sun is out, the power from the panel flows
from the charger common tie, through diodes to each battery terminal,
through a second set of diodes to the load common tie to the load.
At least that's the only way I can see how it could work.
daestrom
| |
| SolarFlaire 2006-01-15, 11:21 am |
| But the "not let the other clusters charge" point is an
old wives tale (I have one).
If one battery cluster is dead and/or pulling the
charger voltage down to some poor charging level the
other battery clusters do not get charged no matter
what you have between them.
The only way to stop batteries in parallel from hogging
charge current from others it to have multiple chargers
or huge resistors for isolation. This eliminates all
good regulation except for trickle charging.
Independant fusing for safety is the only mechanism
that can would on one charger.
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in
message
news:bVsyf.105105$XC4.11104@twister.nyroc.rr.com...
>
> "Windsun" <wind-sun@earthlink.net> wrote in message
>
news:WQqyf.2674$Hd4.406@newsread1.news.pas.earthlink.net...
the diodes are blocking[color=darkred]
>
> It would seem to me you would need two sets of
diodes. A 'set' from the
> common tie point of the charger allowing charge
current into each battery,
> and another 'set' from each battery to a common tie
point that is *isolated*
> from the first, used to supply all the loads.
>
> So when running a load while the sun is out, the
power from the panel flows
> from the charger common tie, through diodes to each
battery terminal,
> through a second set of diodes to the load common tie
to the load.
>
> At least that's the only way I can see how it could
work.
>
> daestrom
>
>
| |
| Steve Spence 2006-01-15, 11:21 am |
| George Ghio wrote:
>
>
> Steve Spence wrote:
>
> Tim this is a complete and utter fabrication. You can use as much as 80%
> max DOD. I prefer 70% myself. What it comes down to is how often you
> discharge your batteries to this level and how long they stay in the low
> state of discharge.
Once again, George is willing to sacrifice your batteries in order to
play solar power consultant online. It's an ego thing for him. PLease
ignore the idiot. Consistant discharge of more than 50% degrades your
battery life. Do not do this!
Car Batteries should not be discharged more than 20%, the plates aren't
designed to handle it.
"11.3. Reducing the average DoD (Depth-of-Discharge), the inverse of
SoC, by proper deep cycle battery sizing will significantly increase a
deep cycle battery life. For example, a pasted plate wet battery with an
average of 50% DoD will last twice as long or more as if it is has an
80% average DoD. A 20% DoD average battery can last up to five times
longer than one with a 50% DoD average. Wet Golf cart batteries will
typically have an average 225 cycles at 80% DoD and 750 cycles at 50%
DoD. For more information of the "50% Rule", please see Chris Gibson's
article on http://www.smartgauge.co.uk/50percent2.html. Always avoid
DoDs that are greater than 80%. The "sweet spot" (optimum DoD for the
greatest amount of power produced over the service life) is generally
somewhere between 20% DoD and 60% DoD average. For the AGM battery
example below the "sweet spot" is approximately 22.5% DoD based on the
greatest amount of power produced."
http://www.uuhome.de/william.darden//carfaq11.htm
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
| Steve Spence 2006-01-15, 11:21 am |
| daestrom wrote:
> "Windsun" <wind-sun@earthlink.net> wrote in message
> news:WQqyf.2674$Hd4.406@newsread1.news.pas.earthlink.net...
>
>
>
> It would seem to me you would need two sets of diodes. A 'set' from the
> common tie point of the charger allowing charge current into each battery,
> and another 'set' from each battery to a common tie point that is *isolated*
> from the first, used to supply all the loads.
>
> So when running a load while the sun is out, the power from the panel flows
> from the charger common tie, through diodes to each battery terminal,
> through a second set of diodes to the load common tie to the load.
>
> At least that's the only way I can see how it could work.
>
> daestrom
>
>
Of course, in reality, no one wires their batteries up with diodes in
off-grid scenarios. Here is a solution looking for a problem by a
armchair theoreticist. Let's not confuse the new guy and just give him
the right way to do it.
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
|
| Think about one way streets. Think about it. With diodes
properly installed, current can only flow FROM a battery, not
into it. Work out the polarities on a piece of paper and you'll
see it, I'm pretty sure.
"SolarFlaire" <sf@hot.mail.invalid> wrote in message
news:2JqdnUx39ZqQTVTeRVn-uQ@golden.net...
: Diodes would not stop one dead cluster from charging
: the others in parallel.
:
: "phatty mo" <ptaylor@nospam.com> wrote in message
: news:15gyf.42$K84.9438@news.uswest.net...
: > Pop wrote:
: > > Well, from the look of the other responses, I guess
: I stand
: > > corrected, but ... I still think it's an unsafe
: setup from both a
: > > personnel and an equipment viewpoint. I'm not
: saying it WILL
: > > happen, but I am saying it MAY happen, and over
: time it's very
: > > possible. Here's some food for thought, and also
: BTW, I'm NOT
: > > passing judgement on any of the opposing posts
: because to a
: > > degree, they are all correct also, but ... just not
: completely.
: > >
: > > Food for thought:
: > > -- A batch of batteries all from the same
: manufacturing lot will
: > > likely be well matched.
: > > -- From different lots, that's not so likely. One
: weaker
: > > battery in the lot will always use the other
: batteries to
: > > maintain its charge, as opposed to all of them
: giving their power
: > > to the load.
: > > -- Battery failure curves and timing is
: notoroiously
: > > unpredictable. Sooner or later one or more
: batteries will begin
: > > to "feed from" the others.
: > > -- Battery replacement will need to be done in
: full group at
: > > once. If one battery gives out over only half or
: less of its
: > > expected life, replacing that one defective battery
: will result
: > > in that battery immediately having to "help" the
: rest of the
: > > batteries to rise to its potential storage
: capacity. To be sure
: > > all batteries are supplying power to the load, they
: all have to
: > > be changed at the same time.
: > >
: > > Constant, daily attention and inspection of the
: battery lot would
: > > be necessary to insure a modicum of safety and
: efficiency.
: > >
: > > Someone mentioned fuses: I assumed each battery
: would be fused,
: > > which looks like it may have been a serious
: oversight on my part.
: > > IMO, fuses would be a must.
: > >
: > > Diode isolation is simple, cheap and pretty much
: guarantees,
: > > within reason, that:
: > > -- Catastrophic currents can never go INTO any
: battery from
: > > another;
: > > -- The batteries only supply power to the load,
: not to each
: > > other, resulting in a loss of efficiency.
: >
: >
: >
: > This is exactly why I used diodes in my (small)
: setup.
: > I have 3 car batteries,and a collection of smaller
: SLA's all different
: > ages,type,sizes,etc. all in parallel with diode
: isolation.
: >
: > I've already had one battery fail,and draw excess
: current.
: > The battery bank was fine,slightly under
: charged,because the bad battery
: > was hogging all the charge current.
: > I actually noticed because the voltage seemed a bit
: low,considering it
: > was a nice sunny day,and the batteries should be
: charging.
: > I got out the DMM,and started measuring each
: batteries voltage,and
: > quickly found the culprit...I unplugged it,and
: instantly the bank was
: > back to normal,and NONE of the other batteries were
: discharged! (just a
: > bit low)
: >
: > That scenario was the *exact* reason I used diodes.
: > That one battery could have deeply discharged the
: rest of the
: > batteries,and killed the whole bank,at the best..
: > Worst case would be a boiling/exploding battery,AND a
: bank of dead
: > worthless batteries.
: >
: > Use schottky or fast recovery diodes (lower voltage
: drop) for less loss.
: > I think the diodes I used on the car batteries are
: '122NQ030' parts
: > (120Amp,low Voltage drop. ~0.4V,I think.)
: > The small loss of efficiency is worth the peace of
: mind,IMO.
: >
: >
: >
: > > Depending on the types of diodes used, the voltage
: losses will
: > > range from 0.15V max up to 0.9V or so with
: germaniums. 0.1V
: > > drops are nominal for the better material diodes.
: Both are
: > > neglible losses when considering the efficiencies
: likely without
: > > them, it just dpeends on your pocket book and
: desire to approach
: > > nominal.
: > >
: > > Someone mentioned blowing the diodes: Not if
: they're specced
: > > right. Diodes have a reliability rating far in
: excess of
: > > batteries. Any blasted-open diode can be
: accurately assumed to
: > > have saved the day in more expensive components.
: > > Combined with fuses you have a pretty reliable
: system that
: > > should last for years. You'll get the best output,
: not go down
: > > should one battery die, and be able to replace just
: one battery
: > > at a time instead of the entire group, knowing it
: won't degrade
: > > efficiency.
: > >
: > > Someone mentioned fear-mongering, and if that's
: what you consider
: > > this, then so be it. It sort of depends on whether
: you want a
: > > fix or repair daily or the best reliability and
: efficiency at a
: > > reasonable cost/watt.
: > > So, yes, you can just parallel them and it'll
: work. But it
: > > can be made to work a lot better and for less money
: in the long
: > > run.
: > >
: > > If you wish to respond to this, that's fine: I'll
: discuss, but I
: > > won't debate or argue; no future in that.
: > >
: > > HTH,
: > >
: > > Pop
: > >
: > >
: > >
: > >
: > >
: > > "Pop" <nobody@devnull.spamcop.net> wrote in message
: > > news:aZWxf.168$Bn4.96@trndny08...
: > > : In the interest of no responses yet, I'll offer
: you what I know
: > > : and let those with actual experience chime in
: when they see
: > > your
: > > : message.
: > > :
: > > : Batteries, I believe, MUST be ISOLATED from each
: other!! So
: > > far,
: > > : assuming the batteries are all in about the same
: condition, you
: > > : probably haven't had any damage yet, but I'm
: pretty sure it's
: > > : coming!
: > > : Something as simple as a diode can be used to
: isolate the
: > > : batteries. The "trick" is to NEVER let one
: battery be able to
: > > : supply power into another battery. Depending on
: the
: > > : circumstances, not having that isolation could
: result in
: > > anything
: > > : from a short battery life to an explosion that
: might be pretty
: > > : but also might be pretty dangerous.
: > > :
: > > : When you tie two batteries together in
: parallel, they will
: > > try
: > > : to instantaneously become one battery. If one
: battery is, say,
: > > : 12.5 volts, and the other battery is, say, 12.0V,
: they will
: > > : source/sink current until they are both the exact
: same voltage.
: > > : The amount of amperage that will generate will
: depend on a
: > > lot
: > > : of things, but mainly the battery's internal
: resistances. For
: > > a
: > > : half volt difference, you may or may not notice
: anything going
: > > : on.
: > > : Now, let's draw some power off them. They
: aren't likely to be
: > > : perfectly identical, so one will start to "drain"
: at a
: > > different
: > > : level than the other. One battery will supply
: current at a
: > > : higher rate than the other. But when the load
: drops, or is
: > > : removed, now the two batteries will again try to
: come to
: > > : equilibrium, which means they will attempt to
: instantaneously
: > > : move to identical charges. Now, THAT situation
: could be many,
: > > : many amps, in the extreme limited only the the
: very low battery
: > > : internal resistances and the wiring resistances.
: In the
: > > extreme
: > > : it could be like shorting one of the batteries
: and
: > > super-charging
: > > : the other way above its safe charge current. And
: bloomo;
: > > : something has to give. With luck, it'll be a
: shortened battery
: > > : life until it becomes simply a resistor. Without
: luck, you
: > > have
: > > : sparks, melting, possible implosion/explosions
: and lots of acid
: > > : flying around in addition to the heat.
: > > :
: > > : I would disconnect the batteries ASAP until you
: can learn more
: > > : about how to isolate them from each other and get
: a safet setup
: > > : in there.
: > > : And yes, I know it's possible to parallel
: batteries in some
: > > : battery operated equipment, but that's a
: different game with
: > > : entirely different possibilities in most cases.
: That's why
: > > most
: > > : things you see have series battery arrangements
: vs parallel -
: > > : much longer battery lifetimes.
: > > :
: > > : HTH, and I'm sure someone with actual experience
: will be along
: > > : soon.
: > > :
: > > : Pop
: > > :
: > > :
: > > :
: > > : "Tim" <tim_usnet@btinternet.com> wrote in message
: > > :
: news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...
: > > :: Apologies if my question seems very basic.
: > > ::
: > > :: I want to create a small off-grid system to
: provide lighting
: > > : and
: > > :: occasional power to a small stable block. To
: this end I have
: > > : purchased
: > > :: the following:
: > > :: 4 x 110Ahr leisure batteries
: > > :: 1 x 80W solar pannel (which came with a small
: 8amp charge
: > > : controller)
: > > :: 1 x 2Kw (modified sine wave) inverter
: > > ::
: > > :: I have assumed that I can connect the batteries
: in parallel,
: > > : and have
: > > :: done this in what may seem to be an odd way by
: connecting each
: > > : one
: > > :: separately to a common point, i.e. I have four
: leads for each
: > > : of +ve
: > > :: and -ve comming to one junction (for each pole).
: From that
: > > : point I have
: > > :: leads running to the inverter.
: > > ::
: > > :: I did this so that I could easily remove any one
: of the
: > > : batteries for
: > > :: off-site charging if required, leaving the rest
: to power the
: > > : system.
: > > ::
: > > :: I have also assumed that I can simply connect
: the appropriate
: > > : terminals
: > > :: from the charge controller to the common
: junctions and the
: > > : solar panel
: > > :: will charge all the batteries together.
: > > ::
: > > :: The charge controller does have a couple of
: terminals that are
: > > : supposed
: > > :: to go to the load (i.e. the inverter) but I
: don't want to use
: > > : them as I
: > > :: will be pushing far too much current through
: such a small
: > > : device.
: > > ::
: > > :: I have read some messages in this group that
: have worried me
: > > as
: > > : I am
: > > :: now concerned that connecting my four batteries
: together will
: > > : cause
: > > :: them to either overheat or be somehow not
: correctly balanced.
: > > ::
: > > :: Am I doing anything wrong in the set-up I have
: proposed. By
: > > the
: > > : way I
: > > :: have not yet actually connected it all together,
: but I have
: > > all
: > > : the
: > > :: kit.
: > > ::
: > > :
: > > :
: > >
: > >
:
:
| |
|
| Same as you normally would. The diodes are part of the load, not
the battery source. You connect to the battery side of the
diodes, in other words.
I find it curious this is such a problem issue for so many
people. I should look up some source URLs for references so
people don't think I'm just making all this up. We'll see; if I
have time, I'll do that.
Pop
"Windsun" <wind-sun@earthlink.net> wrote in message
news:WQqyf.2674$Hd4.406@newsread1.news.pas.earthlink.net...
: And how, exactly, do you charge these batteries if the diodes
are blocking
: incoming current?
:
: -------------------------------------------------------------------------
: Free Solar Discussion Forum:
http://www.wind-sun.com/smf/index.php
: -------------------------------------------------------------------------
: "Pop" <nobody@devnull.spamcop.net> wrote in message
: news:BS8yf.797$Ym3.471@trndny09...
:
: > Diode isolation is simple, cheap and pretty much guarantees,
: > within reason, that:
: > -- Catastrophic currents can never go INTO any battery from
: > another;
: > -- The batteries only supply power to the load, not to each
: > other, resulting in a loss of efficiency.
:
:
| |
|
| You have a point, but ... and I didn't consider multiple charging
in my post because I charge mine one at a time so I can monitor
the health of the battery, but if you're tying all the batteries
together for the charger, then yes, you would need another set
of diodes, in the opposite polarity w/r to the batteries.
Even so, unless it's unattended charging, one would be likely
to note the demise of a battery prior to the charge points
arrival. Just as with the load diodes, all the cathodes or
anodes would tie together at the source/sink points, whichever
one it happened to be.
Sorry bout the omission
Pop
"Windsun" <wind-sun@earthlink.net> wrote in message
news:WQqyf.2674$Hd4.406@newsread1.news.pas.earthlink.net...
: And how, exactly, do you charge these batteries if the diodes
are blocking
: incoming current?
:
: -------------------------------------------------------------------------
: Free Solar Discussion Forum:
http://www.wind-sun.com/smf/index.php
: -------------------------------------------------------------------------
: "Pop" <nobody@devnull.spamcop.net> wrote in message
: news:BS8yf.797$Ym3.471@trndny09...
:
: > Diode isolation is simple, cheap and pretty much guarantees,
: > within reason, that:
: > -- Catastrophic currents can never go INTO any battery from
: > another;
: > -- The batteries only supply power to the load, not to each
: > other, resulting in a loss of efficiency.
:
:
| |
|
|
"SolarFlaire" <sf@hot.mail.invalid> wrote in message
news:qLydnd7gRZkl_VfeRVn-uA@golden.net...
: But the "not let the other clusters charge" point is an
: old wives tale (I have one).
:
: If one battery cluster is dead and/or pulling the
: charger voltage down to some poor charging level the
: other battery clusters do not get charged no matter
: what you have between them.
:
: The only way to stop batteries in parallel from hogging
: charge current from others it to have multiple chargers
: or huge resistors for isolation. This eliminates all
: good regulation except for trickle charging.
:
: Independant fusing for safety is the only mechanism
: that can would on one charger.
:
:
Yessss, but meantime, with the diodes there, the batteries aren't
tied together which would allow the majority to not pop the
minority.
Also, It would be obvious there was a problem with a battery
then, wouldn't it? If that occurred, then the whole system
efficiency is way down too, and something needs repair or
replacement. So, the diodes still protect the good batteries and
the load can continue to draw current vs all the current jumping
into the bad battery.
Resistors? No. Diodes? Yes.
Pop
: "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in
: message
: news:bVsyf.105105$XC4.11104@twister.nyroc.rr.com...
: >
: > "Windsun" <wind-sun@earthlink.net> wrote in message
: >
: news:WQqyf.2674$Hd4.406@newsread1.news.pas.earthlink.net...
: > > And how, exactly, do you charge these batteries if
: the diodes are blocking
: > > incoming current?
: > >
: >
: > It would seem to me you would need two sets of
: diodes. A 'set' from the
: > common tie point of the charger allowing charge
: current into each battery,
: > and another 'set' from each battery to a common tie
: point that is *isolated*
: > from the first, used to supply all the loads.
: >
: > So when running a load while the sun is out, the
: power from the panel flows
: > from the charger common tie, through diodes to each
: battery terminal,
: > through a second set of diodes to the load common tie
: to the load.
: >
: > At least that's the only way I can see how it could
: work.
: >
: > daestrom
: >
: >
:
:
| |
| Harry Chickpea 2006-01-15, 12:21 pm |
| Steve Spence <sspence@green-trust.org> wrote:
>Consistant discharge of more than 50% degrades your
>battery life. Do not do this!
Well... they are TROLLING batteries... :-)
Seriously, I can think of limited situation where you might want to
discharge that much - operating a trolling motor in a small boat is
one of them. Use in a weekender van is another. Short term emergency
power after storms is a third. The use that the battery gets might be
less than a dozen discharges a season, and the max expected life of
the battery about 4 or five years. A discharge past 50% and immediate
recharge isn't great, but the overall cost of operation won't be
seriously affected, because the battery will likely suffer other
problems. Curiously, in the boating world, one source states that the
major cause of battery failure (40%) is not suphation, but positive
plate erosion. It makes sense, if some of these batteries are left on
a charger all the time dockside and rarely discharged.
With the limited recharging rate of the system in question, running
down past 50% would be foolish.
| |
| SolarFlaire 2006-01-15, 1:21 pm |
| When the one way street has only one lane and the
traffic won't let you in, you will never get there.
Nice analogy but if you only charge or only drain your
batteries, then fine.
My batteries are two way streets. They charge and
discharge.
I am positive.
"Pop" <nobody@devnull.spamcop.net> wrote in message
news:uYtyf.817$SD3.780@trndny07...
> Think about one way streets. Think about it. With
diodes
> properly installed, current can only flow FROM a
battery, not
> into it. Work out the polarities on a piece of paper
and you'll
> see it, I'm pretty sure.
>
> "SolarFlaire" <sf@hot.mail.invalid> wrote in message
> news:2JqdnUx39ZqQTVTeRVn-uQ@golden.net...
> : Diodes would not stop one dead cluster from
charging
> : the others in parallel.
> :
> : "phatty mo" <ptaylor@nospam.com> wrote in message
> : news:15gyf.42$K84.9438@news.uswest.net...
> : > Pop wrote:
> : > > Well, from the look of the other responses, I
guess
> : I stand
> : > > corrected, but ... I still think it's an unsafe
> : setup from both a
> : > > personnel and an equipment viewpoint. I'm not
> : saying it WILL
> : > > happen, but I am saying it MAY happen, and over
> : time it's very
> : > > possible. Here's some food for thought, and
also
> : BTW, I'm NOT
> : > > passing judgement on any of the opposing posts
> : because to a
> : > > degree, they are all correct also, but ... just
not
> : completely.
> : > >
> : > > Food for thought:
> : > > -- A batch of batteries all from the same
> : manufacturing lot will
> : > > likely be well matched.
> : > > -- From different lots, that's not so likely.
One
> : weaker
> : > > battery in the lot will always use the other
> : batteries to
> : > > maintain its charge, as opposed to all of them
> : giving their power
> : > > to the load.
> : > > -- Battery failure curves and timing is
> : notoroiously
> : > > unpredictable. Sooner or later one or more
> : batteries will begin
> : > > to "feed from" the others.
> : > > -- Battery replacement will need to be done in
> : full group at
> : > > once. If one battery gives out over only half
or
> : less of its
> : > > expected life, replacing that one defective
battery
> : will result
> : > > in that battery immediately having to "help"
the
> : rest of the
> : > > batteries to rise to its potential storage
> : capacity. To be sure
> : > > all batteries are supplying power to the load,
they
> : all have to
> : > > be changed at the same time.
> : > >
> : > > Constant, daily attention and inspection of the
> : battery lot would
> : > > be necessary to insure a modicum of safety and
> : efficiency.
> : > >
> : > > Someone mentioned fuses: I assumed each
battery
> : would be fused,
> : > > which looks like it may have been a serious
> : oversight on my part.
> : > > IMO, fuses would be a must.
> : > >
> : > > Diode isolation is simple, cheap and pretty
much
> : guarantees,
> : > > within reason, that:
> : > > -- Catastrophic currents can never go INTO any
> : battery from
> : > > another;
> : > > -- The batteries only supply power to the
load,
> : not to each
> : > > other, resulting in a loss of efficiency.
> : >
> : >
> : >
> : > This is exactly why I used diodes in my (small)
> : setup.
> : > I have 3 car batteries,and a collection of
smaller
> : SLA's all different
> : > ages,type,sizes,etc. all in parallel with diode
> : isolation.
> : >
> : > I've already had one battery fail,and draw excess
> : current.
> : > The battery bank was fine,slightly under
> : charged,because the bad battery
> : > was hogging all the charge current.
> : > I actually noticed because the voltage seemed a
bit
> : low,considering it
> : > was a nice sunny day,and the batteries should be
> : charging.
> : > I got out the DMM,and started measuring each
> : batteries voltage,and
> : > quickly found the culprit...I unplugged it,and
> : instantly the bank was
> : > back to normal,and NONE of the other batteries
were
> : discharged! (just a
> : > bit low)
> : >
> : > That scenario was the *exact* reason I used
diodes.
> : > That one battery could have deeply discharged the
> : rest of the
> : > batteries,and killed the whole bank,at the best..
> : > Worst case would be a boiling/exploding
battery,AND a
> : bank of dead
> : > worthless batteries.
> : >
> : > Use schottky or fast recovery diodes (lower
voltage
> : drop) for less loss.
> : > I think the diodes I used on the car batteries
are
> : '122NQ030' parts
> : > (120Amp,low Voltage drop. ~0.4V,I think.)
> : > The small loss of efficiency is worth the peace
of
> : mind,IMO.
> : >
> : >
> : >
> : > > Depending on the types of diodes used, the
voltage
> : losses will
> : > > range from 0.15V max up to 0.9V or so with
> : germaniums. 0.1V
> : > > drops are nominal for the better material
diodes.
> : Both are
> : > > neglible losses when considering the
efficiencies
> : likely without
> : > > them, it just dpeends on your pocket book and
> : desire to approach
> : > > nominal.
> : > >
> : > > Someone mentioned blowing the diodes: Not
if
> : they're specced
> : > > right. Diodes have a reliability rating far in
> : excess of
> : > > batteries. Any blasted-open diode can be
> : accurately assumed to
> : > > have saved the day in more expensive
components.
> : > > Combined with fuses you have a pretty
reliable
> : system that
> : > > should last for years. You'll get the best
output,
> : not go down
> : > > should one battery die, and be able to replace
just
> : one battery
> : > > at a time instead of the entire group, knowing
it
> : won't degrade
> : > > efficiency.
> : > >
> : > > Someone mentioned fear-mongering, and if that's
> : what you consider
> : > > this, then so be it. It sort of depends on
whether
> : you want a
> : > > fix or repair daily or the best reliability and
> : efficiency at a
> : > > reasonable cost/watt.
> : > > So, yes, you can just parallel them and
it'll
> : work. But it
> : > > can be made to work a lot better and for less
money
> : in the long
> : > > run.
> : > >
> : > > If you wish to respond to this, that's fine:
I'll
> : discuss, but I
> : > > won't debate or argue; no future in that.
> : > >
> : > > HTH,
> : > >
> : > > Pop
> : > >
> : > >
> : > >
> : > >
> : > >
> : > > "Pop" <nobody@devnull.spamcop.net> wrote in
message
> : > > news:aZWxf.168$Bn4.96@trndny08...
> : > > : In the interest of no responses yet, I'll
offer
> : you what I know
> : > > : and let those with actual experience chime in
> : when they see
> : > > your
> : > > : message.
> : > > :
> : > > : Batteries, I believe, MUST be ISOLATED from
each
> : other!! So
> : > > far,
> : > > : assuming the batteries are all in about the
same
> : condition, you
> : > > : probably haven't had any damage yet, but I'm
> : pretty sure it's
> : > > : coming!
> : > > : Something as simple as a diode can be used
to
> : isolate the
> : > > : batteries. The "trick" is to NEVER let one
> : battery be able to
> : > > : supply power into another battery. Depending
on
> : the
> : > > : circumstances, not having that isolation
could
> : result in
> : > > anything
> : > > : from a short battery life to an explosion
that
> : might be pretty
> : > > : but also might be pretty dangerous.
> : > > :
> : > > : When you tie two batteries together in
> : parallel, they will
> : > > try
> : > > : to instantaneously become one battery. If
one
> : battery is, say,
> : > > : 12.5 volts, and the other battery is, say,
12.0V,
> : they will
> : > > : source/sink current until they are both the
exact
> : same voltage.
> : > > : The amount of amperage that will generate
will
> : depend on a
> : > > lot
> : > > : of things, but mainly the battery's internal
> : resistances. For
> : > > a
> : > > : half volt difference, you may or may not
notice
> : anything going
> : > > : on.
> : > > : Now, let's draw some power off them. They
> : aren't likely to be
> : > > : perfectly identical, so one will start to
"drain"
> : at a
> : > > different
> : > > : level than the other. One battery will
supply
> : current at a
> : > > : higher rate than the other. But when the
load
> : drops, or is
> : > > : removed, now the two batteries will again try
to
> : come to
> : > > : equilibrium, which means they will attempt to
> : instantaneously
> : > > : move to identical charges. Now, THAT
situation
> : could be many,
> : > > : many amps, in the extreme limited only the
the
> : very low battery
> : > > : internal resistances and the wiring
resistances.
> : In the
> : > > extreme
> : > > : it could be like shorting one of the
batteries
> : and
> : > > super-charging
> : > > : the other way above its safe charge current.
And
> : bloomo;
> : > > : something has to give. With luck, it'll be a
> : shortened battery
> : > > : life until it becomes simply a resistor.
Without
> : luck, you
> : > > have
> : > > : sparks, melting, possible
implosion/explosions
> : and lots of acid
> : > > : flying around in addition to the heat.
> : > > :
> : > > : I would disconnect the batteries ASAP until
you
> : can learn more
> : > > : about how to isolate them from each other and
get
> : a safet setup
> : > > : in there.
> : > > : And yes, I know it's possible to parallel
> : batteries in some
> : > > : battery operated equipment, but that's a
> : different game with
> : > > : entirely different possibilities in most
cases.
> : That's why
> : > > most
> : > > : things you see have series battery
arrangements
> : vs parallel -
> : > > : much longer battery lifetimes.
> : > > :
> : > > : HTH, and I'm sure someone with actual
experience
> : will be along
> : > > : soon.
> : > > :
> : > > : Pop
> : > > :
> : > > :
> : > > :
> : > > : "Tim" <tim_usnet@btinternet.com> wrote in
message
> : > > :
> :
news:1137193492.772414.23100@f14g2000cwb.googlegroups.com...
> : > > :: Apologies if my question seems very basic.
> : > > ::
> : > > :: I want to create a small off-grid system to
> : provide lighting
> : > > : and
> : > > :: occasional power to a small stable block. To
> : this end I have
> : > > : purchased
> : > > :: the following:
> : > > :: 4 x 110Ahr leisure batteries
> : > > :: 1 x 80W solar pannel (which came with a
small
> : 8amp charge
> : > > : controller)
> : > > :: 1 x 2Kw (modified sine wave) inverter
> : > > ::
> : > > :: I have assumed that I can connect the
batteries
> : in parallel,
> : > > : and have
> : > > :: done this in what may seem to be an odd way
by
> : connecting each
> : > > : one
> : > > :: separately to a common point, i.e. I have
four
> : leads for each
> : > > : of +ve
> : > > :: and -ve comming to one junction (for each
pole).
> : From that
> : > > : point I have
> : > > :: leads running to the inverter.
> : > > ::
> : > > :: I did this so that I could easily remove any
one
> : of the
> : > > : batteries for
> : > > :: off-site charging if required, leaving the
rest
> : to power the
> : > > : system.
> : > > ::
> : > > :: I have also assumed that I can simply
connect
> : the appropriate
> : > > : terminals
> : > > :: from the charge controller to the common
> : junctions and the
> : > > : solar panel
> : > > :: will charge all the batteries together.
> : > > ::
> : > > :: The charge controller does have a couple of
> : terminals that are
> : > > : supposed
> : > > :: to go to the load (i.e. the inverter) but I
> : don't want to use
> : > > : them as I
> : > > :: will be pushing far too much current through
> : such a small
> : > > : device.
> : > > ::
> : > > :: I have read some messages in this group that
> : have worried me
> : > > as
> : > > : I am
> : > > :: now concerned that connecting my four
batteries
> : together will
> : > > : cause
> : > > :: them to either overheat or be somehow not
> : correctly balanced.
> : > > ::
> : > > :: Am I doing anything wrong in the set-up I
have
> : proposed. By
> : > > the
> : > > : way I
> : > > :: have not yet actually connected it all
together,
> : but I have
> : > > all
> : > > : the
> : > > :: kit.
> : > > ::
> : > > :
> : > > :
> : > >
> : > >
> :
> :
>
>
| |
| Steve Spence 2006-01-15, 1:21 pm |
| Pop wrote:
> Same as you normally would. The diodes are part of the load, not
> the battery source. You connect to the battery side of the
> diodes, in other words.
>
> I find it curious this is such a problem issue for so many
> people. I should look up some source URLs for references so
> people don't think I'm just making all this up. We'll see; if I
> have time, I'll do that.
>
> Pop
>
Why bother. Thousands of off-grid home including ours are wired up
without such diodes. There is no need or benefit. The official and
accepted method is series/parallel strings of batteries all connected to
each other, and fused between the pack and the inverter. This is a
solution looking for a problem.
see http://www.backwoodssolar.com/inter...meTechnical.htm for the
correct method of wiring an off-grid battery pack.
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
| Steve Spence 2006-01-15, 1:21 pm |
| Pop wrote:
> You have a point, but ... and I didn't consider multiple charging
> in my post because I charge mine one at a time so I can monitor
> the health of the battery, but if you're tying all the batteries
> together for the charger, then yes, you would need another set
> of diodes, in the opposite polarity w/r to the batteries.
>
> Even so, unless it's unattended charging, one would be likely
> to note the demise of a battery prior to the charge points
> arrival. Just as with the load diodes, all the cathodes or
> anodes would tie together at the source/sink points, whichever
> one it happened to be.
>
> Sorry bout the omission
>
> Pop
This would be a major problem with more than 6 batteries in the pack.
Why would you charge each one individually? How can you power your house
if you have a battery offline for charging. You then would have unevenly
charged batteries. This is not an acceptqble way to rig a pack.
--
Steve Spence
Dir., Green Trust, http://www.green-trust.org
Contributing Editor, http://www.off-grid.net
http://www.rebelwolf.com/essn.html
| |
| SolarFlaire 2006-01-15, 1:21 pm |
| OK. Let's see if I can exemplify further why this
cannot work.
I have four (4) 12 Volt batteries in parallel with
diodes in series with each cluster pointing the
direction to charge then only from one charger.
I have a dead (shorted) cell or two in one 12 volt
cluster. This pulls the charging voltage down to 8-10
volts and the other cells in that cluster are boiling
there water off.
Do you think the 8-10 volts coming from the charger
will charger the other three TWELVE (12) volt batteries
clusters in parallel?
We know they will not discharge into the bad battery
cluster with the shorted cells. It does present other
positives but does not work for this problem and
generally does not work at all.
You battery cells already lots of plate surface area in
parallel inside each cell.
"Pop" <nobody@devnull.spamcop.net> wrote in message
news:Kcuyf.198$Iw3.111@trndny06...
>
> "SolarFlaire" <sf@hot.mail.invalid> wrote in message
> news:qLydnd7gRZkl_VfeRVn-uA@golden.net...
> : But the "not let the other clusters charge" point
is an
> : old wives tale (I have one).
> :
> : If one battery cluster is dead and/or pulling the
> : charger voltage down to some poor charging level
the
> : other battery clusters do not get charged no matter
> : what you have between them.
> :
> : The only way to stop batteries in parallel from
hogging
> : charge current from others it to have multiple
chargers
> : or huge resistors for isolation. This eliminates
all
> : good regulation except for trickle charging.
> :
> : Independant fusing for safety is the only mechanism
> : that can would on one charger.
> :
> :
> Yessss, but meantime, with the diodes there, the
batteries aren't
> tied together which would allow the majority to not
pop the
> minority.
> Also, It would be obvious there was a problem
with a battery
> then, wouldn't it? If that occurred, then the whole
system
> efficiency is way down too, and something needs
repair or
> replacement. So, the diodes still protect the good
batteries and
> the load can continue to draw current vs all the
current jumping
> into the bad battery.
>
> Resistors? No. Diodes? Yes.
>
> Pop
>
>
> : "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com>
wrote in
> : message
> : news:bVsyf.105105$XC4.11104@twister.nyroc.rr.com...
> : >
> : > "Windsun" <wind-sun@earthlink.net> wrote in
message
> : >
> :
news:WQqyf.2674$Hd4.406@newsread1.news.pas.earthlink.net...
> : > > And how, exactly, do you charge these batteries
if
> : the diodes are blocking
> : > > incoming current?
> : > >
> : >
> : > It would seem to me you would need two sets of
> : diodes. A 'set' from the
> : > common tie point of the charger allowing charge
> : current into each battery,
> : > and another 'set' from each battery to a common
tie
> : point that is *isolated*
> : > from the first, used to supply all the loads.
> : >
> : > So when running a load while the sun is out, the
> : power from the panel flows
> : > from the charger common tie, through diodes to
each
> : battery terminal,
> : > through a second set of diodes to the load common
tie
> : to the load.
> : >
> : > At least that's the only way I can see how it
could
> : work.
> : >
> : > daestrom
> : >
> : >
> :
> :
>
>
| |
| Steve Spence 2006-01-15, 1:21 pm |
| Pop wrote:
> You're usually pretty good, Steve; I'm surprised at you.
>
>
You shouldn't be surprised. You are advocating a bad method of battery
wiring. I'm explaining the correct method.
http://www.backwoodssolar.com/inter.. | | |