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Home > Archive > Alternative Power sources > January 2006 > Lead Acid battery charging question
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Lead Acid battery charging question
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| Hi Folks,
Have just picked up a low power ( about 200w ) wind powered battery
charger, that I plan to install on the family's holiday shack that has
no mains power.
The charge regulator that comes with the kit regulates for charging a
24vdc battery.
Most of the load devices I plan to use are of the 12v variety
(automotive) as they are cheap and plentiful.
My plan is to bolt two 12v batteries in series to connect to the
charger, and use a tapping between the two batteries to give me, in
effect, two separate 12v supplies. One for all the 12v lights, and the
other for everything else (radio, small water pump in the shower, and
maybe a fan).
My question is this... As the two batteries will obviously discharge at
different rates given their different loads, will a single charger cause
problems with over charging one battery while under charging the other?
Or would this effect be so small as to be insignificant?
Thanks in anticipation,
Pal
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| Eric Sears 2006-01-21, 6:21 am |
| On Sat, 21 Jan 2006 17:40:25 +1030, Pal <"gtsubs at tpg dot com dot
au"> wrote:
>Hi Folks,
>
>Have just picked up a low power ( about 200w ) wind powered battery
>charger, that I plan to install on the family's holiday shack that has
>no mains power.
>
>The charge regulator that comes with the kit regulates for charging a
>24vdc battery.
>
>Most of the load devices I plan to use are of the 12v variety
>(automotive) as they are cheap and plentiful.
>
>My plan is to bolt two 12v batteries in series to connect to the
>charger, and use a tapping between the two batteries to give me, in
>effect, two separate 12v supplies. One for all the 12v lights, and the
>other for everything else (radio, small water pump in the shower, and
>maybe a fan).
>
>My question is this... As the two batteries will obviously discharge at
>different rates given their different loads, will a single charger cause
>problems with over charging one battery while under charging the other?
>Or would this effect be so small as to be insignificant?
>
>Thanks in anticipation,
>
>Pal
The simple answer is "it depends!" - ie , it depends how balanced your
loads turn out to be.
Mot folks would say its not a good idea - though if you give a regular
equalising charge , (by bypassing the regulator for a few hours and
checking that the battery that gasses most if kept topped with water),
you might get away with it.
Other solutions would include usinga 24v to 12v (switchmode) converter
to charge a 12 volt battery (an MX60 would do the job expensively).
Or perhaps you might use a 24v inverter and just use grid devices.
MSQ invereters are fairly cheap and run most devices ok.
All the best with a solution
Eric
Abtt
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| William P.N. Smith 2006-01-21, 9:21 am |
| Pal <"gtsubs at tpg dot com dot au"> wrote:
>My question is this... As the two batteries will obviously discharge at
>different rates given their different loads, will a single charger cause
>problems with over charging one battery while under charging the other?
Exactly the problem, even with equalizing charges one battery will be
chronically overcharged while the other one will be chronically
undercharged.
Go with 12V and convert or adapt your supply to charge 12V.
| |
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| William P.N. Smith wrote:
> Pal <"gtsubs at tpg dot com dot au"> wrote:
>
>
>
> Exactly the problem, even with equalizing charges one battery will be
> chronically overcharged while the other one will be chronically
> undercharged.
>
> Go with 12V and convert or adapt your supply to charge 12V.
All things considered, I'm leaning toward using 24V batteries rather
than 12V, and adding a 24 - 12V converter for a single 12V supply line.
Found one in a local electronics retailer that will deliver 12V @ 20A
which should be more than I need, and keeps the 24V charging side of
things as simple as possible. It's even been suggested on another group
where I asked the same question, that 24V truck batteries would provide
more Ah per $. Guess I'll have to hit my local battery outlets to check
it out...
Thanks Eric and William for your comments and suggestions.
Regards,
Pal
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| William P.N. Smith 2006-01-21, 11:21 am |
| Pal <"gtsubs at tpg dot com dot au"> wrote:
>All things considered, I'm leaning toward using 24V batteries rather
>than 12V, and adding a 24 - 12V converter for a single 12V supply line.
One detail, those converters will have a quiescent current drain that
may be significant. The new ones I put in my golf carts draw 100mA
all the time (remind me to start another thread).
>where I asked the same question, that 24V truck batteries would provide
>more Ah per $. Guess I'll have to hit my local battery outlets to check
IME, golf cart batteries will give you the best bang for the buck,
though you'll need 4 of them to get 24V, you'll have 200AH for about
$200, and they are made for deep-cycle applications.
| |
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| William P.N. Smith wrote:
> Pal <"gtsubs at tpg dot com dot au"> wrote:
>
>
>
> One detail, those converters will have a quiescent current drain that
> may be significant. The new ones I put in my golf carts draw 100mA
> all the time (remind me to start another thread).
>
I was wondering about that. The sales blurb I found didn't give any
efficiency details. However, the product photo did show an on/off switch
on the front panel - so I guess I could just switch it off when we're
not there, or don't need to use the 12V appliances. I could still run
24V lights directly from the battery(s) even without the converter.
>
>
>
> IME, golf cart batteries will give you the best bang for the buck,
> though you'll need 4 of them to get 24V, you'll have 200AH for about
> $200, and they are made for deep-cycle applications.
Thanks for the tip. Will check it out with my local suppliers.
| |
| Bruce in Alaska 2006-01-22, 5:21 pm |
| In article <43d204db.906748@news.clear.net.nz>,
phoneme@025379386.for.email.address (Eric Sears) wrote:
> On Sat, 21 Jan 2006 17:40:25 +1030, Pal <"gtsubs at tpg dot com dot
> au"> wrote:
>
>
> The simple answer is "it depends!" - ie , it depends how balanced your
> loads turn out to be.
> Mot folks would say its not a good idea - though if you give a regular
> equalising charge , (by bypassing the regulator for a few hours and
> checking that the battery that gasses most if kept topped with water),
> you might get away with it.
> Other solutions would include usinga 24v to 12v (switchmode) converter
> to charge a 12 volt battery (an MX60 would do the job expensively).
> Or perhaps you might use a 24v inverter and just use grid devices.
> MSQ invereters are fairly cheap and run most devices ok.
>
> All the best with a solution
>
> Eric
>
> Abtt
This is similar to the system I have at a Remotesite Cabin in Alaska.
3 Kw Diesel Genset powers a Trace 2624/400amp/hour battery. Numar
24/12-25Amp Switchmode Dc/Dc Converter charging a pair if L16's in
Series, that provides 12Vdc for the Threeway Fridge, Radios, and CD/DVD
player. Got'a have tunes, even out in the bush......
Bruce in alaska
--
add a <2> before @
| |
| Mr Wizzard 2006-01-22, 6:21 pm |
|
"Pal" <"gtsubs at tpg dot com dot au"> wrote in message
news:43d1de2b$1@dnews.tpgi.com.au...
> Hi Folks,
>
> Have just picked up a low power ( about 200w ) wind powered battery
> charger, that I plan to install on the family's holiday shack that has
> no mains power.
>
> The charge regulator that comes with the kit regulates for charging a
> 24vdc battery.
>
> Most of the load devices I plan to use are of the 12v variety
> (automotive) as they are cheap and plentiful.
>
> My plan is to bolt two 12v batteries in series to connect to the
> charger, and use a tapping between the two batteries to give me, in
> effect, two separate 12v supplies. One for all the 12v lights, and the
> other for everything else (radio, small water pump in the shower, and
> maybe a fan).
>
> My question is this... As the two batteries will obviously discharge at
> different rates given their different loads, will a single charger cause
> problems with over charging one battery while under charging the other?
> Or would this effect be so small as to be insignificant?
Get two of these things:
http://www.batterymart.com/battery.mv?p=ACC-12BC1000D-1
they have a chip in them that does 2-stage charging, runs em
up to the 14.2V, then falls back to 13.8 for float. Hook one
up to each battery (even though batteries are in series), they
are isolated and would work well - these things are great.
Only thing is that you'd need 2 wall outlets (or power strip).
These things are very accureate, work very well, and cheap.
>
> Thanks in anticipation,
>
> Pal
| |
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| Mr Wizzard wrote:
> Get two of these things:
>
> http://www.batterymart.com/battery.mv?p=ACC-12BC1000D-1
>
> they have a chip in them that does 2-stage charging, runs em
> up to the 14.2V, then falls back to 13.8 for float. Hook one
> up to each battery (even though batteries are in series), they
> are isolated and would work well - these things are great.
> Only thing is that you'd need 2 wall outlets (or power strip).
> These things are very accureate, work very well, and cheap.
>
>
I'm confused.
I'm installing a wind generator (because I have no mains supply) that
produces 3 phase ac, with a voltage and frequency that vary with wind
speed. I have a charging regulator that takes the 3 phase and turns it
into 24vdc for battery charging.
Exactly how is a mains powered 120v battery charger going to help me here?
| |
| Mr Wizzard 2006-01-23, 3:21 am |
|
"Pal" <"gtsubs at tpg dot com dot au"> wrote in message
news:43d40eba@dnews.tpgi.com.au...
> Mr Wizzard wrote:
>
>
>
> I'm confused.
>
> I'm installing a wind generator (because I have no mains supply) that
> produces 3 phase ac, with a voltage and frequency that vary with wind
> speed. I have a charging regulator that takes the 3 phase and turns it
> into 24vdc for battery charging.
>
> Exactly how is a mains powered 120v battery charger going to help me here?
Doh! - there I go again blowing thru posts without reading the whole thread.
How electronics inclined are you ? - there are some really
nice chips out there (Maxum etc), and you can probably
throw something together in no time. This might help:
http://www.maxim-ic.com/appnotes.cfm/appnote_number/621
Should be able to front this one of the many .regulator chips out there.
The important thing is to be able to do the 2-stage charging for
proper equalization and proper float.
| |
|
| Mr Wizzard wrote:
>
> Doh! - there I go again blowing thru posts without reading the whole thread.
>
> How electronics inclined are you ? - there are some really
> nice chips out there (Maxum etc), and you can probably
> throw something together in no time. This might help:
> http://www.maxim-ic.com/appnotes.cfm/appnote_number/621
> Should be able to front this one of the many .regulator chips out there.
> The important thing is to be able to do the 2-stage charging for
> proper equalization and proper float.
>
I'm an electrical technician by trade with 20+ years building automation
experience (lifts, escallators, automatic doors, parking station
equipment etc.), and completed about half of an advanced certificate in
electronic engineering at night school a few years back until I ran out
of the bits of it I was interested in (didn't need the piece of paper!),
so I should be able to nut it out... (if I had the spare time that is).
Based on advice and comments from the good folk in this group, and also
some others on sci.electronics.misc, I've about decided to use a 24-12v
converter for 12v loads, and leave the 24v charging system dealing with
a single battery.
I've found a converter that will give me 20a load capacity for about
$100 (US$75), and I think that will be good enough for what I need.
....unless of course, someone can point out something else I've overlooked?
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"Pal" <"gtsubs at tpg dot com dot au"> wrote in message
news:43d4a838$1@dnews.tpgi.com.au...
> I've found a converter that will give me 20a load capacity for about $100
> (US$75), and I think that will be good enough for what I need.
>
> ...unless of course, someone can point out something else I've overlooked?
I've read Homepower magazine for about 10 years. Generally 24 volts is
dominant now in most off-grid systems.
but more electronic gear -- inverters etc is just more complicated.
Especially with possible damage due to static and lightning strikes.
Just having two 12 volt batts in series ( or 4 x 6 volts) and balancing the
12 volts loads on each half would eliminate any need for a converter. If you
have a single 12 volts load, then just alternate the load on each side, that
could be done easily when you do the battery maintenance, maybe every 3
months or something.
| |
| Derek Broughton 2006-01-24, 10:21 am |
| bw wrote:
> Just having two 12 volt batts in series ( or 4 x 6 volts) and balancing
> the 12 volts loads on each half would eliminate any need for a converter.
"Just". Balancing loads across 12V batteries is a pretty big "just".
> If you have a single 12 volts load, then just alternate the load on each
> side, that could be done easily when you do the battery maintenance, maybe
> every 3 months or something.
Ye Gods! That's hardly balancing. From everything I've read, it's an open
invitation to a fire. I can't speak from experience, as I haven't wanted
to try it, but I can speak with the voice of experience that a high current
draw from a battery _can_ start a fire. I don't want to go there again.
--
derek
| |
|
| Derek Broughton wrote:
> bw wrote:
>
>
> "Just". Balancing loads across 12V batteries is a pretty big "just".
>
>
> Ye Gods! That's hardly balancing. From everything I've read, it's an open
> invitation to a fire. I can't speak from experience, as I haven't wanted
> to try it, but I can speak with the voice of experience that a high current
> draw from a battery _can_ start a fire. I don't want to go there again.
> --
> derek
I am Arasu from india. May be all you can excuse me if I am wrong. It
will be better idea to use a DC to DC converter as sugested by Mr .Pal.
It will save the batteries and all the unwanted problems associted with
damaged battries. Alternating load may not work. The the battery
where load is connected will be under charged and the battery where no
load is connected will be over charged.
I uderstand the batrries will be connected to wind power generator
allways. In such a case all the battries in a stiring should be charged
and discharged at the same rate and all the battries in the same sting
should have the same AH capacity.
An over charged battrey may loose the active material due heating
and overcharging. An uder charged loose capacity due to sulfation.
Arasu.
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