20th September 2004 08:18 PM
Lead acid battery efficiency
I'm looking to tweak my battery amp-hr monitor project's accuracy. It measures current out of my deep cycle battery to calculate drain.
From what I've heard, the "coulometric efficiency" of lead acid is around 70%, so 10 amp-hrs of charge stores only 7 amp-hrs to the battery.
Doesn't it get worse with high charging currents than low currents? Doesn't temp or state-of-charge also affect it?
Does anybody know further information?
20th September 2004 11:48 PM
I would say it depends greatly on your battery, that draw amps (if I remember correctly I saw a chart in a panansonic battery datasheet) , the charge voltage/amps, temperature etc. Probably the closes you can get is just measuring how much you put in, and how much you take out.
22nd September 2004 06:08 PM
You can safely say that all heat created when charging is a loss of energy just like in any application. The heat will increase with higher charge current as well as with higher discharge currents. A lead acid battery has its optimum temperature for charging and also for storage this is specified in most battery data sheet, usually from 15 to 18C. The data sheet also holds info on recommended charge current and discharge current.
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