Charging backup batteries
 

I have four GC2, 230 amp/hr batteries hooked up in series for 24vdc in my backup power system. The battery says 120 min / 75 amp on the label, the Napa site says they are about 230 amp/hr. I assume the label is showing the max discharge rate.

Anyway, the question is, how many amps can I charge these batteries in series? I figured 15 amps per battery would be safe so 60amps total. But then I was thinking since they are in series would all those amps flow through the first batteries in the series and damage it?

Ended up charging at 25 amps to be safe, but a max figure would be nice as the faster I can charge them them the less time I run the generator. Charger is a three step type, bulk, topping and float.

On a much smaller scale, mostly flashlights and remote controllers, etc. batteries are used in a series formation. The rechargeable ones are recharged in a parallel formation. For that reason I would tend to charge in parallel. Years ago I was given an an analogy of filling water buckets with a hose. In series, the first bucket would have to be filled before the next bucket starts. In parallel there would be multiple outlets from the hose filling all the buckets at the same.

'In a series circuit, the current through each of the components is the same, and the voltage across the circuit is the sum of the voltages across each component. In a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component.'