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Charging gel cells in series
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captainvi...@gmail.com
Jun 26, 2015, 12:08:38 PM6/26/15
to
I have a customer who wants to buy twelve 12.0 volt 8.0 AH gel cells from me. He uses these in his fire alarm panels and wants to keep a quantity in stock for when one of these panels goes down for battery failure. I've explained to him about the need for trickle charging these while they're sitting on the shelf, and rather than sell him 12 individual trickle chargers I was wondering if anyone knows of a cost effective series charger whereby I could put perhaps 6 in series and charge them all at the same time. I would probably not want to go above 6 and I would not do this with anything other than new batteries all of the same type and rating. Thanks, Lenny
Tom Miller
Jun 26, 2015, 12:15:38 PM6/26/15
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<captainvi...@gmail.com> wrote in message
news:c2dd3f4d-ca38-479a...@googlegroups.com...
++++++++++++++++++++++++++++++++++++++++++++++++++++
Gel cells should all be charged in parallel from a constant voltage source.
Usually about 13.8 to 14,0 volts. You might install a fuse in each leg of
the summing point just to be safe.
news:c2dd3f4d-ca38-479a...@googlegroups.com...
Gel cells should all be charged in parallel from a constant voltage source.
Usually about 13.8 to 14,0 volts. You might install a fuse in each leg of
the summing point just to be safe.
captainvi...@gmail.com
Jun 26, 2015, 1:46:52 PM6/26/15
to
On Friday, June 26, 2015 at 12:08:38 PM UTC-4, captainvi...@gmail.com wrote:
> I have a customer who wants to buy twelve 12.0 volt 8.0 AH gel cells from me. He uses these in his fire alarm panels and wants to keep a quantity in stock for when one of these panels goes down for battery failure. I've explained to him about the need for trickle charging these while they're sitting on the shelf, and rather than sell him 12 individual trickle chargers I was wondering if anyone knows of a cost effective series charger whereby I could put perhaps 6 in series and charge them all at the same time. I would probably not want to go above 6 and I would not do this with anything other than new batteries all of the same type and rating. Thanks, Lenny
I was under the impression that parallel charging was not the way to go because it is difficult if not virtually impossible to equalize the current through each battery. Batteries having a lower terminal voltage would draw more current. The inverse would then be true with a higher terminal voltage. In series the entire string gets the same amount of current. Lenny
> I have a customer who wants to buy twelve 12.0 volt 8.0 AH gel cells from me. He uses these in his fire alarm panels and wants to keep a quantity in stock for when one of these panels goes down for battery failure. I've explained to him about the need for trickle charging these while they're sitting on the shelf, and rather than sell him 12 individual trickle chargers I was wondering if anyone knows of a cost effective series charger whereby I could put perhaps 6 in series and charge them all at the same time. I would probably not want to go above 6 and I would not do this with anything other than new batteries all of the same type and rating. Thanks, Lenny
Bennett
Jun 26, 2015, 1:50:37 PM6/26/15
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at least, that charging a bunch of batteries in series is appropriate.
Or am I missing something?
Allodoxaphobia
Jun 26, 2015, 2:29:31 PM6/26/15
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set of cells -- from 6 to 8 of'em depending on the chemical technology?
The OP did say " ...new batteries all of the same type and rating ..."
Jonesy
Robert Roland
Jun 26, 2015, 5:50:39 PM6/26/15
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On Fri, 26 Jun 2015 10:46:48 -0700 (PDT), captainvi...@gmail.com
wrote:
>I was under the impression that parallel charging was not the way to go because it is difficult if not virtually impossible to equalize the current through each battery.
Lead (and lithium) based batteries are charged to a specific voltage,
and are therefore well suited for parallel operation.
During standby charge, you want to control the voltage, not the
current. In fact, even if the batteries are not closely matched, you
can perfectly well keep them on standby charge in parallel. The
battery that has more self-discharge will then automatically draw more
current.
You can run batteries in series, but they must then be closely
matched. A battery is simply a set of closely matched cells connected
in series.
In your situation, just hook several batteries in parallel and use one
charger to keep them all fully charged.
To be completely safe, you might want to fully charge them
individually before you connect them together. If you connect two
batteries with considerably differing charge state, one battery will
charge the other at an uncontrolled current.
--
RoRo
wrote:
>I was under the impression that parallel charging was not the way to go because it is difficult if not virtually impossible to equalize the current through each battery.
and are therefore well suited for parallel operation.
During standby charge, you want to control the voltage, not the
current. In fact, even if the batteries are not closely matched, you
can perfectly well keep them on standby charge in parallel. The
battery that has more self-discharge will then automatically draw more
current.
You can run batteries in series, but they must then be closely
matched. A battery is simply a set of closely matched cells connected
in series.
In your situation, just hook several batteries in parallel and use one
charger to keep them all fully charged.
To be completely safe, you might want to fully charge them
individually before you connect them together. If you connect two
batteries with considerably differing charge state, one battery will
charge the other at an uncontrolled current.
--
RoRo
et...@whidbey.com
Jun 26, 2015, 8:39:17 PM6/26/15
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On Fri, 26 Jun 2015 23:50:43 +0200, Robert Roland <fa...@ddress.no>
wrote:
And if the batteries are charged in parallel it makes no difference if
one is removed. But if charged in series once the customer needs
another battery the customer must remove ALL the batteries in that
series string from the charger.
Eric
wrote:
one is removed. But if charged in series once the customer needs
another battery the customer must remove ALL the batteries in that
series string from the charger.
Eric
Phil Allison
Jun 26, 2015, 11:46:06 PM6/26/15
to
Bennett wrote:
>
> Since the cells in each battery are in series, it seems logical, to me
> at least, that charging a bunch of batteries in series is appropriate.
> Or am I missing something?
** The cells in a particular battery have a great deal in common - eg same origin, age, capacity, number and level of charges and discharges.
>
> Since the cells in each battery are in series, it seems logical, to me
> at least, that charging a bunch of batteries in series is appropriate.
> Or am I missing something?
Various 12 batteries likely have none of the above in common so charging in series will not suit more a than one of them.
In the OP's case, with all new and unused batteries of the same type, parallel charging with a fixed maximum voltage of 13.8 is the most practical method as one can use a standard charger.
Each battery will initially draw the current it needs until all are fully charged, then the current will taper off to a trickle in each.
Gel and SLA cells behave very differently to NiCd and NiMh cells.
.... Phil
captainvi...@gmail.com
Jun 27, 2015, 9:36:39 AM6/27/15
to
On Friday, June 26, 2015 at 12:08:38 PM UTC-4, captainvi...@gmail.com wrote:
> I have a customer who wants to buy twelve 12.0 volt 8.0 AH gel cells from me. He uses these in his fire alarm panels and wants to keep a quantity in stock for when one of these panels goes down for battery failure. I've explained to him about the need for trickle charging these while they're sitting on the shelf, and rather than sell him 12 individual trickle chargers I was wondering if anyone knows of a cost effective series charger whereby I could put perhaps 6 in series and charge them all at the same time. I would probably not want to go above 6 and I would not do this with anything other than new batteries all of the same type and rating. Thanks, Lenny
I can imagine haw this might be a concern in high current charging, but how important in float or trickle applications is it that all batteries be fed with the same series resistance, such as equal length leads from the charging source? Lenny
Arfa Daily
Jun 27, 2015, 10:34:44 AM6/27/15
to
>
> To be completely safe, you might want to fully charge them
> individually before you connect them together. If you connect two
> batteries with considerably differing charge state, one battery will
> charge the other at an uncontrolled current.
> --
> RoRo
>
series fuse that someone else suggested, making sure of course that the
charge source has sufficient voltage overhead to still allow the battery to
reach a full charge voltage level after taking the diode drop into
consideration. That way, no battery that's connected can become a charge
current source for any other, no matter what their relative charge states
are.
Arfa
Ian Malcolm
Jun 27, 2015, 11:00:50 AM6/27/15
to
Phil Allison <palli...@gmail.com> wrote in
news:9c31b936-72c8-42b9...@googlegroups.com:
*EXACTLY*
The charger should be rated for the maximum total AH capacity to be
connected to it and needs to be set for SLA batterys and to have a
constant float mode.
A 12V 10W bulb in series with each battery will prevent excessive current
flow allowing discharged batteries to be recharged safely and also
provides visual indication of any shorts.
--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL
news:9c31b936-72c8-42b9...@googlegroups.com:
The charger should be rated for the maximum total AH capacity to be
connected to it and needs to be set for SLA batterys and to have a
constant float mode.
A 12V 10W bulb in series with each battery will prevent excessive current
flow allowing discharged batteries to be recharged safely and also
provides visual indication of any shorts.
--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL
Phil Allison
Jun 27, 2015, 8:58:22 PM6/27/15
to
Ian Malcolm wrote:
> Phil Allison
They also normally have a "current limit" feature that operates when a partly or fully discharged battery is connected, which ought not apply in the OP's case.
> A 12V 10W bulb in series with each battery will prevent excessive current
> flow allowing discharged batteries to be recharged safely and also
> provides visual indication of any shorts.
** With bulbs like that fitted, a SLA charger rated at say 3 or 4 amps would do fine with 6 x 7AH batteries at once in the OP's situation.
.... Phil
> Phil Allison
> >
>
> > ** The cells in a particular battery have a great deal in common - eg
> > same origin, age, capacity, number and level of charges and
> > discharges.
> >
> > Various 12 batteries likely have none of the above in common so
> > charging in series will not suit more a than one of them.
> >
> > In the OP's case, with all new and unused batteries of the same type,
> > parallel charging with a fixed maximum voltage of 13.8 is the most
> > practical method as one can use a standard charger.
> >
> > Each battery will initially draw the current it needs until all are
> > fully charged, then the current will taper off to a trickle in each.
> >
> > Gel and SLA cells behave very differently to NiCd and NiMh cells.
>
> *EXACTLY*
> The charger should be rated for the maximum total AH capacity to be
> connected to it and needs to be set for SLA batterys and to have a
> constant float mode.
** Most Gel/SLA chargers have affixed maximum voltage between 13.8 and 14 volts which IS the float mode. A fully charged 6 cell battery will draw only a trickle of current at this voltage.
>
> > ** The cells in a particular battery have a great deal in common - eg
> > same origin, age, capacity, number and level of charges and
> > discharges.
> >
> > Various 12 batteries likely have none of the above in common so
> > charging in series will not suit more a than one of them.
> >
> > In the OP's case, with all new and unused batteries of the same type,
> > parallel charging with a fixed maximum voltage of 13.8 is the most
> > practical method as one can use a standard charger.
> >
> > Each battery will initially draw the current it needs until all are
> > fully charged, then the current will taper off to a trickle in each.
> >
> > Gel and SLA cells behave very differently to NiCd and NiMh cells.
>
> *EXACTLY*
> The charger should be rated for the maximum total AH capacity to be
> connected to it and needs to be set for SLA batterys and to have a
> constant float mode.
They also normally have a "current limit" feature that operates when a partly or fully discharged battery is connected, which ought not apply in the OP's case.
> A 12V 10W bulb in series with each battery will prevent excessive current
> flow allowing discharged batteries to be recharged safely and also
> provides visual indication of any shorts.
.... Phil
Michael A. Terrell
Jun 27, 2015, 9:25:35 PM6/27/15
to
will need more charging current. What happens when he has less than six
batteries in stock? Why complicate things?
Rheilly Phoull
Jun 27, 2015, 10:53:18 PM6/27/15
to
"Michael A. Terrell" wrote in message
news:8sGdnejLpuOQ0BLI...@earthlink.com...
As I recall in a past lifetime, Vesta had a display rack that held a
collection of 2 - 6 or 12volt batteries.
It came with a fixed current trickle charger for all the batteries to be
connected in series.
It would seem to me the matter is being made into a mountain rather than a
hillock, the answer would
seem to me to be a matter of education since both methods would work in the
right hands.
news:8sGdnejLpuOQ0BLI...@earthlink.com...
collection of 2 - 6 or 12volt batteries.
It came with a fixed current trickle charger for all the batteries to be
connected in series.
It would seem to me the matter is being made into a mountain rather than a
hillock, the answer would
seem to me to be a matter of education since both methods would work in the
right hands.
Phil Allison
Jun 28, 2015, 2:07:15 AM6/28/15
to
Rheilly Phoull wrote:
> It would seem to me the matter is being made into a mountain
> rather than a hillock, the answer would seem to me to be a
> matter of education since both methods would work in the
> right hands.
** Sure, it's possible to make the 6 x 12V Gel batteries in series idea work.
> It would seem to me the matter is being made into a mountain
> rather than a hillock, the answer would seem to me to be a
> matter of education since both methods would work in the
> right hands.
But you would have to design and build a one off charger rather than use a cheap, off the shelf unit and a few bulbs.
Plus outputting over 84V DC is getting a bit hazardous too.
... Phil
pedro
Aug 3, 2015, 7:17:05 AM8/3/15
to
>On Friday, June 26, 2015 at 12:08:38 PM UTC-4, captainvi...@gmail.com wrote:
>> I have a customer who wants to buy twelve 12.0 volt 8.0 AH gel cells from me. He uses these in his fire alarm panels and wants to keep a quantity in stock for when one of these panels goes down for battery failure. I've explained to him about the need for trickle charging these while they're sitting on the shelf, and rather than sell him 12 individual trickle chargers I was wondering if anyone knows of a cost effective series charger whereby I could put perhaps 6 in series and charge them all at the same time. I would probably not want to go above 6 and I would not do this with anything other than new batteries all of the same type and rating. Thanks, Lenny
>
>I was under the impression that parallel charging was not the way to go because it is difficult if not virtually impossible to equalize the current through each battery. Batteries having a lower terminal voltage would draw more current. The inverse would then be true with a higher terminal voltage. In series the entire string gets the same amount of current. Lenny
Lead-acid batteries charging is VOLTAGE-controlled, unlike NiXX. So
>> I have a customer who wants to buy twelve 12.0 volt 8.0 AH gel cells from me. He uses these in his fire alarm panels and wants to keep a quantity in stock for when one of these panels goes down for battery failure. I've explained to him about the need for trickle charging these while they're sitting on the shelf, and rather than sell him 12 individual trickle chargers I was wondering if anyone knows of a cost effective series charger whereby I could put perhaps 6 in series and charge them all at the same time. I would probably not want to go above 6 and I would not do this with anything other than new batteries all of the same type and rating. Thanks, Lenny
>
>I was under the impression that parallel charging was not the way to go because it is difficult if not virtually impossible to equalize the current through each battery. Batteries having a lower terminal voltage would draw more current. The inverse would then be true with a higher terminal voltage. In series the entire string gets the same amount of current. Lenny
parallel charging - well, floating actually - is what is required.
Refer to the cell manufacturer for the appropriate voltage and do as
Tom Miller suggested.
mike
Aug 3, 2015, 3:38:23 PM8/3/15
to
with each so the current can't be hogged by one. Some "smart"
chargers might object to that, but a dumb float charger should work
just fine.
I'd suggest that, if your need is so infrequent such that you need to
recharge 'em, you're stocking too many replacements.
Find a high-turnover supplier with short delivery time and stock
fewer batteries. Fresher is better.
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