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| Author |
Control of battery charger
|
|
|
| I have a basic 24 volt 40 amp battery charger. It has the basic transformer
and rectifier in it. The input voltage is 240-250 volts 50 cycles AC.
I am trying to control it to charge a set of batteries (4 x 6 Volt T 105)
that in turn run an inverter (24 volt to 240 volts AC; 2.5 Kw) that in turn
runs 3 computers, 3 printers and the phone system. Eventually this system
might be set up as an emergency power supply to run the fridge if we have a
power failure, with a manual change over switch for the fridge.
There is a manual change over switch for the computers etc so they can run
either from the mains or the inverter, and they are currently running from
the mains until I overcome this overcharging problem.
The 40 amp charger's transformer has some tappings, but tends to overcharge
the batteries. The input voltage tends to vary somewhat from the incoming
mains (236-250 or so)
Changing the tappings manually does not work, as when the load or input
voltage change the amount going into the batteries can change a lot.
(Excluding what goes into the inverter).
I have a second battery charger (automatic) that seems to do a fine job, and
it holds the batteries at around 27.2 volts with a trickle charge of point 7
amps. This charger cannot supply enough power to the batteries when the
inverter is coupled up hence the need for the above listed 40 amp charger.
The problem is that the 40 amp charger seems to vary its voltage and
charging rate quite a bit, causing the batteries to use quite a bit of
water, or at lower tappings undercharge the batteries.
I am looking for some way of controlling the input power so as to hold the
output voltage stable.
I am looking at something like an electronic motor controller or dimmer that
can hold the output voltage around 27 volts DC (with a pot so I can trim the
voltage if ever required).
It needs to be fully automatic, so it needs to sense the battery voltage,
and trim in input power accordingly.
I would think something that can handle around 6 amps @ 250 volts would be
needed.
BTW running both chargers together does not work, already tried that.
So far the 40 amp charger has not had to put out any more than 30 amps when
supplying the inverter, but if the batteries get a bit low, that could
increase to the full 40 amps
The power going to the inverter varies with the load, and so this controller
needs to be able to sense the DC voltage and boost or reduce the output of
the transformer accordingly to maintain a constant DC voltage.
The second choice is something that will switch between the tappings to
control the 40 amp battery charger transformer, but this could lead to
hunting, so an electronic controller such as a motor controller seems to be
a better choice.
So I am looking for something that will sense the battery voltage of around
27 volts DC and will then automatically control a motor controller or dimmer
circuit that will vary the power going into the 240 volt transformer and
hold the DC voltage constant.
Anyone know of any circuits that will control this battery charger for me?
| |
| Robert Morein 2005-12-10, 4:21 pm |
|
<RamRod Sword of Baal> wrote in message news:439b1eae$1@quokka.wn.com.au...
>I have a basic 24 volt 40 amp battery charger. It has the basic transformer
>and rectifier in it. The input voltage is 240-250 volts 50 cycles AC.
>
>
Go to Lowes and pick up a high frequency car charger for about $50. Throw
what you have in the dumpster.
The damage done to batteries by unsophisticated chargers such as the one you
describe are enormous. It really isn't possible to fix, because your charger
is missing 90% of the circuitry in a modern charger.
| |
|
|
"Robert Morein" <nowhere@nowhere.com> wrote in message
news:pe2dnQHNdOQ8qwbenZ2dnUVZ_vudnZ2d@giganews.com...
>
> <RamRod Sword of Baal> wrote in message
news:439b1eae$1@quokka.wn.com.au...
transformer[color=darkred]
> Go to Lowes and pick up a high frequency car charger for about $50. Throw
> what you have in the dumpster.
>
> The damage done to batteries by unsophisticated chargers such as the one
you
> describe are enormous. It really isn't possible to fix, because your
charger
> is missing 90% of the circuitry in a modern charger.
>
Kinda doubt your going to find a 50 CYCLE anything at Lowes
| |
| Jim Rusling 2005-12-10, 5:21 pm |
| "Robert Morein" <nowhere@nowhere.com> wrote:
>
><RamRod Sword of Baal> wrote in message news:439b1eae$1@quokka.wn.com.au...
>Go to Lowes and pick up a high frequency car charger for about $50. Throw
>what you have in the dumpster.
>
>The damage done to batteries by unsophisticated chargers such as the one you
>describe are enormous. It really isn't possible to fix, because your charger
>is missing 90% of the circuitry in a modern charger.
>
I don't think that would work since he has a 24 volt system.
--
Jim Rusling
More or Less Retired
Mustang, OK
http://www.rusling.org
| |
| Robert Morein 2005-12-10, 9:21 pm |
|
"SQLit" <sqlit@qwest.net> wrote in message
news:odHmf.30$gc7.1175@news.uswest.net...
>
> "Robert Morein" <nowhere@nowhere.com> wrote in message
> news:pe2dnQHNdOQ8qwbenZ2dnUVZ_vudnZ2d@giganews.com...
> news:439b1eae$1@quokka.wn.com.au...
> transformer
> you
> charger
> Kinda doubt your going to find a 50 CYCLE anything at Lowes
>
High frequency chargers don't care.
| |
| nospam.clare.nce@sny.der.on.ca 2005-12-11, 2:21 am |
| On Sun, 11 Dec 2005 04:26:33 +1000, <RamRod Sword of Baal> wrote:
>I have a basic 24 volt 40 amp battery charger. It has the basic transformer
>and rectifier in it. The input voltage is 240-250 volts 50 cycles AC.
>
>
>
>I am trying to control it to charge a set of batteries (4 x 6 Volt T 105)
>that in turn run an inverter (24 volt to 240 volts AC; 2.5 Kw) that in turn
>runs 3 computers, 3 printers and the phone system. Eventually this system
>might be set up as an emergency power supply to run the fridge if we have a
>power failure, with a manual change over switch for the fridge.
>
>
>
>There is a manual change over switch for the computers etc so they can run
>either from the mains or the inverter, and they are currently running from
>the mains until I overcome this overcharging problem.
>
>
>
>The 40 amp charger's transformer has some tappings, but tends to overcharge
>the batteries. The input voltage tends to vary somewhat from the incoming
>mains (236-250 or so)
>
>
>
>Changing the tappings manually does not work, as when the load or input
>voltage change the amount going into the batteries can change a lot.
>(Excluding what goes into the inverter).
>
>
>
>I have a second battery charger (automatic) that seems to do a fine job, and
>it holds the batteries at around 27.2 volts with a trickle charge of point 7
>amps. This charger cannot supply enough power to the batteries when the
>inverter is coupled up hence the need for the above listed 40 amp charger.
>
>
>
>The problem is that the 40 amp charger seems to vary its voltage and
>charging rate quite a bit, causing the batteries to use quite a bit of
>water, or at lower tappings undercharge the batteries.
>
>
>
>I am looking for some way of controlling the input power so as to hold the
>output voltage stable.
>
>
>
>I am looking at something like an electronic motor controller or dimmer that
>can hold the output voltage around 27 volts DC (with a pot so I can trim the
>voltage if ever required).
>
>
>
>It needs to be fully automatic, so it needs to sense the battery voltage,
>and trim in input power accordingly.
>
>
>
>I would think something that can handle around 6 amps @ 250 volts would be
>needed.
>
>
>
>BTW running both chargers together does not work, already tried that.
>
>
>
>So far the 40 amp charger has not had to put out any more than 30 amps when
>supplying the inverter, but if the batteries get a bit low, that could
>increase to the full 40 amps
>
>
>
>The power going to the inverter varies with the load, and so this controller
>needs to be able to sense the DC voltage and boost or reduce the output of
>the transformer accordingly to maintain a constant DC voltage.
>
>
>
>The second choice is something that will switch between the tappings to
>control the 40 amp battery charger transformer, but this could lead to
>hunting, so an electronic controller such as a motor controller seems to be
>a better choice.
>
>
>
>So I am looking for something that will sense the battery voltage of around
>27 volts DC and will then automatically control a motor controller or dimmer
>circuit that will vary the power going into the 240 volt transformer and
>hold the DC voltage constant.
>
>
>
>Anyone know of any circuits that will control this battery charger for me?
>
>
>
Get a saturating core / ferroresonant voltage regulator - Sola
Constant Voltage Transformer or whatever is available where you are.
They hold voltage steady to within a couple of volts over a fairly
wide input range.The ones I have hold 115 volts out from 95 to 125 in.
Heavy, and terribly inefficient - they make good heaters - but they
work and they are, being totally electromagnetic, virtually
bulletproof if properly sized and ventilated.
| |
| nospam.clare.nce@sny.der.on.ca 2005-12-11, 2:21 am |
| On Sat, 10 Dec 2005 19:37:08 -0500, "Robert Morein"
<nowhere@nowhere.com> wrote:
>
>"SQLit" <sqlit@qwest.net> wrote in message
>news:odHmf.30$gc7.1175@news.uswest.net...
>High frequency chargers don't care.
>
How about that 240 volt primary???
| |
| Eric Sears 2005-12-11, 5:21 am |
| Greetings
As far as I can see you are located in Oz so I won't hazard a guess
where you might buy something.
However the system you are using (albeit heavy duty) is something I
know and have used for years (ie - transformer chargers).
Now there are at least two ways of controlling the input to your
batteries from the charger
- one is to have the charger switching on/off according to the
battery voltage, in order to maintain the voltage in a reasonably
narrow range. Your inverter should not care about a 1 to 2 volt swing
in battery voltage.This has been the basis for most charge controllers
for many years - though the later models use clever switching regimes
to ensure such things as the battery receiving an equalising charge
every so often. Usually these switch the high current side of the
charger - though my own system (a simple hydro charger which I
designed)) switches the high voltage side, because much lower
switching currents are involved - and a.c.
- the other method, which you refer to, uses a triac, fet or some
other device in a "switched mode" circuit to effectively vary the
amount of input. Designing and building such a circuit is not trivial,
though I have recently found the basics of a circuit which may do it
reasonably easily. But electronic noise is often a consequence.
You don't mention whether you have the skills to build a circuit - but
there are a good number of controller circuits of the first type
available on the internet (Google - 'regulator circuit'?!)
I don't know if you will find a circuit to handle 40 amps at 24 volts
- but they are probably around.
An alternative would be to try any of the renewable energy co's and
obtain a regulator off the shelf which will do what you want. They
should be under AU$500, and possibly considerably less.
(The things I build cost <NZ$50 in parts - but they are not "state of
the art" - they simply work ok for me and stop batteries overcharging
but they handle 20 amps at most).
Best wishes
Eric.
On Sun, 11 Dec 2005 04:26:33 +1000, <RamRod Sword of Baal> wrote:
>I have a basic 24 volt 40 amp battery charger. It has the basic transformer
>and rectifier in it. The input voltage is 240-250 volts 50 cycles AC.
>
>
>
>I am trying to control it to charge a set of batteries (4 x 6 Volt T 105)
>that in turn run an inverter (24 volt to 240 volts AC; 2.5 Kw) that in turn
>runs 3 computers, 3 printers and the phone system. Eventually this system
>might be set up as an emergency power supply to run the fridge if we have a
>power failure, with a manual change over switch for the fridge.
>
>
>
>There is a manual change over switch for the computers etc so they can run
>either from the mains or the inverter, and they are currently running from
>the mains until I overcome this overcharging problem.
>
>
>
>The 40 amp charger's transformer has some tappings, but tends to overcharge
>the batteries. The input voltage tends to vary somewhat from the incoming
>mains (236-250 or so)
>
>
>
>Changing the tappings manually does not work, as when the load or input
>voltage change the amount going into the batteries can change a lot.
>(Excluding what goes into the inverter).
>
>
>
>I have a second battery charger (automatic) that seems to do a fine job, and
>it holds the batteries at around 27.2 volts with a trickle charge of point 7
>amps. This charger cannot supply enough power to the batteries when the
>inverter is coupled up hence the need for the above listed 40 amp charger.
>
>
>
>The problem is that the 40 amp charger seems to vary its voltage and
>charging rate quite a bit, causing the batteries to use quite a bit of
>water, or at lower tappings undercharge the batteries.
>
>
>
>I am looking for some way of controlling the input power so as to hold the
>output voltage stable.
>
>
>
>I am looking at something like an electronic motor controller or dimmer that
>can hold the output voltage around 27 volts DC (with a pot so I can trim the
>voltage if ever required).
>
>
>
>It needs to be fully automatic, so it needs to sense the battery voltage,
>and trim in input power accordingly.
>
>
>
>I would think something that can handle around 6 amps @ 250 volts would be
>needed.
>
>
>
>BTW running both chargers together does not work, already tried that.
>
>
>
>So far the 40 amp charger has not had to put out any more than 30 amps when
>supplying the inverter, but if the batteries get a bit low, that could
>increase to the full 40 amps
>
>
>
>The power going to the inverter varies with the load, and so this controller
>needs to be able to sense the DC voltage and boost or reduce the output of
>the transformer accordingly to maintain a constant DC voltage.
>
>
>
>The second choice is something that will switch between the tappings to
>control the 40 amp battery charger transformer, but this could lead to
>hunting, so an electronic controller such as a motor controller seems to be
>a better choice.
>
>
>
>So I am looking for something that will sense the battery voltage of around
>27 volts DC and will then automatically control a motor controller or dimmer
>circuit that will vary the power going into the 240 volt transformer and
>hold the DC voltage constant.
>
>
>
>Anyone know of any circuits that will control this battery charger for me?
>
>
>
>
| |
| RoughRider 2005-12-11, 11:21 pm |
| What you are describing is perhaps a "manual" charger at best. It is not
meant for automatic charging. But you are already aware of this.
The older "magnetic" chargers that we have in the telecom world are called
"saturable reactor" regulated. In essense, there is a CHOKE (looks like a
small transformer in series with the main transformer) in the primary. It
has a DC winding in it. The regulator passes DC current through this choke
to saturate the iron core. In this way, the choke is controlled, which
limits the voltage going to the main transformer primary, which will affect
the secondary voltage, and thus the charger output voltage. With less than
an AMP of current, one can throttle may times that amount in the output of
the secondary.
More sophisticated designs also have some ferro-resonant aspects to this.
Google FLOTROL for one example of this design.
However, this method is not efficient, has a poor power factor, and is heavy
with magnetics. These rectifiers are cheap on the used market... or talk to
a telecom scrap dealer. Some companies are eliminating 24V equipment in
favour of 48V. Shipping would be expensive due to weight.
Newer switch mode designs would work better and as others have stated, are
relatively inexpensive.
Good luck.
<RamRod Sword of Baal> wrote in message news:439b1eae$1@quokka.wn.com.au...
>I have a basic 24 volt 40 amp battery charger. It has the basic transformer
>and rectifier in it. The input voltage is 240-250 volts 50 cycles AC.
| |
| Pete C 2005-12-12, 9:21 am |
| On Sun, 11 Dec 2005 04:26:33 +1000, <RamRod Sword of Baal> wrote:
>I have a basic 24 volt 40 amp battery charger. It has the basic transformer
>and rectifier in it. The input voltage is 240-250 volts 50 cycles AC.
>
>
>
>I am trying to control it to charge a set of batteries (4 x 6 Volt T 105)
>that in turn run an inverter (24 volt to 240 volts AC; 2.5 Kw) that in turn
>runs 3 computers, 3 printers and the phone system. Eventually this system
>might be set up as an emergency power supply to run the fridge if we have a
>power failure, with a manual change over switch for the fridge.
>
>
>
>There is a manual change over switch for the computers etc so they can run
>either from the mains or the inverter, and they are currently running from
>the mains until I overcome this overcharging problem.
>
>
>
>The 40 amp charger's transformer has some tappings, but tends to overcharge
>the batteries. The input voltage tends to vary somewhat from the incoming
>mains (236-250 or so)
>
>
>
>Changing the tappings manually does not work, as when the load or input
>voltage change the amount going into the batteries can change a lot.
>(Excluding what goes into the inverter).
>
>
>
>I have a second battery charger (automatic) that seems to do a fine job, and
>it holds the batteries at around 27.2 volts with a trickle charge of point 7
>amps. This charger cannot supply enough power to the batteries when the
>inverter is coupled up hence the need for the above listed 40 amp charger.
>
>
>
>The problem is that the 40 amp charger seems to vary its voltage and
>charging rate quite a bit, causing the batteries to use quite a bit of
>water, or at lower tappings undercharge the batteries.
>
>
>
>I am looking for some way of controlling the input power so as to hold the
>output voltage stable.
>
>
>
>I am looking at something like an electronic motor controller or dimmer that
>can hold the output voltage around 27 volts DC (with a pot so I can trim the
>voltage if ever required).
>
>
>
>It needs to be fully automatic, so it needs to sense the battery voltage,
>and trim in input power accordingly.
>
>
>
>I would think something that can handle around 6 amps @ 250 volts would be
>needed.
>
>
>
>BTW running both chargers together does not work, already tried that.
>
>
>
>So far the 40 amp charger has not had to put out any more than 30 amps when
>supplying the inverter, but if the batteries get a bit low, that could
>increase to the full 40 amps
>
>
>
>The power going to the inverter varies with the load, and so this controller
>needs to be able to sense the DC voltage and boost or reduce the output of
>the transformer accordingly to maintain a constant DC voltage.
>
>
>
>The second choice is something that will switch between the tappings to
>control the 40 amp battery charger transformer, but this could lead to
>hunting, so an electronic controller such as a motor controller seems to be
>a better choice.
>
>
>
>So I am looking for something that will sense the battery voltage of around
>27 volts DC and will then automatically control a motor controller or dimmer
>circuit that will vary the power going into the 240 volt transformer and
>hold the DC voltage constant.
>
>
>
>Anyone know of any circuits that will control this battery charger for me?
>
>
Hi,
The 40A charger could be used on a timeswitch to limit charge time and
therefore gassing. Also to charge at night when the mains voltage
should be more stable.
The other charger could be used the rest of the time, so it does a
'bulk' charge and then the 40A charger does a short 'absorption'
charge.
Wonder if fully charged cells gas as soon as a charge current is
applied or there is a delay. If the latter the 40A charger could be
put on a 'simmerstat' (from an old hot plate) so it applies charge
current at short intervals.
If you want instant full recharging after an outage the above won't
give you that.
The best way to go is to invest a minimum percentage of the battery
costs on chargers; it makes no sense to risk expensive batteries with
cheap chargers.
cheers,
Pete.
| |
| William P.N. Smith 2005-12-12, 11:21 am |
| <RamRod Sword of Baal> wrote:
>I have a basic 24 volt 40 amp battery charger. It has the basic transformer
>and rectifier in it. The input voltage is 240-250 volts 50 cycles AC.
>The 40 amp charger's transformer has some tappings, but tends to overcharge
>the batteries. The input voltage tends to vary somewhat from the incoming
>mains (236-250 or so)
Why not set it up for the maximum output and use an external charge
controller (not a shunt type!) to do the right thing for your
batteries?
| |
|
|
"Robert Morein" <nowhere@nowhere.com> wrote in message
news:pe2dnQHNdOQ8qwbenZ2dnUVZ_vudnZ2d@giganews.com...
>
> <RamRod Sword of Baal> wrote in message
> news:439b1eae$1@quokka.wn.com.au...
> Go to Lowes and pick up a high frequency car charger for about $50. Throw
> what you have in the dumpster.
>
> The damage done to batteries by unsophisticated chargers such as the one
> you describe are enormous. It really isn't possible to fix, because your
> charger is missing 90% of the circuitry in a modern charger.
I am in Cairns Australia, I should have mentioned that, and I do not know of
a Lowes here except for a place that sells clothes.
I checked the net and found a place in the US, butthat would not be much
good for me.
Thanks for your help.
| |
|
|
<nospam.clare.nce@sny.der.on.ca> wrote in message
news:nienp1lmq725qm7ib93fjbj4spjjl24c3p@4ax.com...
> On Sun, 11 Dec 2005 04:26:33 +1000, <RamRod Sword of Baal> wrote:
>
> Get a saturating core / ferroresonant voltage regulator - Sola
> Constant Voltage Transformer or whatever is available where you are.
> They hold voltage steady to within a couple of volts over a fairly
> wide input range.The ones I have hold 115 volts out from 95 to 125 in.
> Heavy, and terribly inefficient - they make good heaters - but they
> work and they are, being totally electromagnetic, virtually
> bulletproof if properly sized and ventilated.
Yes I have two of them, to stabilize some other gear, but not really what I
am after. Besides that the are quite expensive.
| |
|
|
"William P.N. Smith" <news05@compusmiths.com> wrote in message
news:m12rp1tgqavk2v5258glccb0lqjvopdk09@4ax.com...
> <RamRod Sword of Baal> wrote:
>
>
> Why not set it up for the maximum output and use an external charge
> controller (not a shunt type!) to do the right thing for your
> batteries?
I will look at these and see what I can find.
| |
| Daniel Armstrong 2005-12-14, 9:21 pm |
|
<RamRod Sword of Baal> wrote in message news:43a03b61@quokka.wn.com.au...
>
> "William P.N. Smith" <news05@compusmiths.com> wrote in message
> news:m12rp1tgqavk2v5258glccb0lqjvopdk09@4ax.com...
>
>
> I will look at these and see what I can find.
>
I would also use a pair of .5 or 1 farad 12V stiffening capacitors (the kind
normally used for automotive amplifier installations) in series (for 24v)
hooked across the wires between the output of the charger and input of the
charge controller to filter the pulsating DC from the charger into smooth DC
that the charge controller expects. Make sure the caps are rated for at
least 20V continuous /24V surge so that the output of the charger doesn't
overvolt and destroy them.
| |
| SolarFlare 2005-12-14, 9:21 pm |
| Capacitors in series also need voltage splitting
resistors to ensure all the voltage isn't dropped
across one cap blowing it or exceeding it's working
voltage.
"Daniel Armstrong" <danielthechskid@mchsi.com> wrote in
message news:0Y2of.404237$084.378350@attbi_s22...
> I would also use a pair of .5 or 1 farad 12V
stiffening capacitors (the kind
> normally used for automotive amplifier installations)
in series (for 24v)
> hooked across the wires between the output of the
charger and input of the
> charge controller to filter the pulsating DC from the
charger into smooth DC
> that the charge controller expects. Make sure the
caps are rated for at
> least 20V continuous /24V surge so that the output of
the charger doesn't
> overvolt and destroy them.
>
>
| |
| William P.N. Smith 2005-12-15, 12:21 am |
| "SolarFlare" <sfl.are@hot.mail.invalid> wrote:
>Capacitors in series also need voltage splitting
>resistors to ensure all the voltage isn't dropped
>across one cap blowing it or exceeding it's working
>voltage.
IME the cap with the higher voltage will leak enough to balance the
voltage out. It's not a question of "exceed this voltage by a
millivolt and I'll explode", but more a matter of "as the voltage
increases past my ratings I'll start to leak a bit more.
But voltage splitting resistors (or light bulbs) aren't a bad idea.
The caps are definitely a good idea, but check the peak voltage, as
that's what the caps will charge to...
|
|
|
|
|