Charging a 24V System
Charging a 24V System
(OP)
I have two 12VDC batteries connected in parallel (i.e., a jumper from the positive on battery A to the negative on Battery B, then the loads coming off the positive on battery B and the negative on battery A).
I described this to my supplier and he sold me a 12V SunSaver 6 charging circuit. My electrician connected the charging circuit on the SunSaver to the same leads as the load (positive to "B" and negative to "A") and after a week the system is at 13V (both batteries are down to 6.5V).
This obviously isn't right. I thought he should connect the charging circuit to one of the batteries and let the charge equalize through the jumper, but he said that wouldn't work (he didn't say why, I am just a dumb mechanical engineer after all). Do I need to scrap the 12V SunSaver and buy a 24V or can I hook up to a single battery?
I described this to my supplier and he sold me a 12V SunSaver 6 charging circuit. My electrician connected the charging circuit on the SunSaver to the same leads as the load (positive to "B" and negative to "A") and after a week the system is at 13V (both batteries are down to 6.5V).
This obviously isn't right. I thought he should connect the charging circuit to one of the batteries and let the charge equalize through the jumper, but he said that wouldn't work (he didn't say why, I am just a dumb mechanical engineer after all). Do I need to scrap the 12V SunSaver and buy a 24V or can I hook up to a single battery?
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
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RE: Charging a 24V System
Connecting across one battery will charge that one battery and leave the other uncharged.
Is your system offline during this time? Can you afford you charge each battery individually timewise?
You could possibly charge both batteries in parallel, but there are some risks in not getting a full charge to both batteries.
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RE: Charging a 24V System
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RE: Charging a 24V System
This system has to work all the time so I can't take a battery off line to charge it. It is also pretty remote and unmanned so manual intervention wouldn't work.
The two deep discharge batteries are both brand new, I guess my best bet is to replace the 12V charger with a 24V charger and accept the risk of not charging evenly. The load is 1 amp for 3 seconds every three minutes (drawing current of about 0.4 amp-hr/day. I think that works out to about 10 W/day and I have a 40 W solar panel so I don't think that I'm stressing the batteries.
David
RE: Charging a 24V System
Isn't the solar panel supposed to charge up the batteries so that you can even out the charge/discharge cycles? Ostensibly, then, the solar panels ought to be charging the batteries. If they're not, then either something is wrong with the charging circuit, or there's insufficient panel capacity, either because the load is higher than what was anticipated, or the solar input is lower than anticipated, or the panels have degraded.
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RE: Charging a 24V System
David
RE: Charging a 24V System
You have stated parallel then promptly describe a series hook-up.
If it is truly hooked up in series you have a 24V system and need a 24V solar charger.
I will also point out that time is of the essence. If those batteries are gel-cells you should probably just order new ones now as leaving modern GCs drained for more than a few hours destroys them.
Your supplier heard "parallel" and sent you the proper 12V charger. The new 24V charger should be hooked up just as you've described.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Charging a 24V System
Yes, this is a series hook up. Using two 12V batteries to power a 24V load.
David
RE: Charging a 24V System
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RE: Charging a 24V System
David
RE: Charging a 24V System