Maximum charging current calculation in series/parallel


Solar Enthusiast
For an independent charger driven off of a generator, I am slightly confused about calculating the maximum amps I can send to the batteries.

The batteries can take 30% of C20 - which is 230ah in this case.

However, I have these batteries wired in parallel for a total of 460ah, and so this is where I run into some confusion.

According to this link I would calculate 30% of 460ah yielding a maximum current of 138 amps. I'm assuming this would only apply in bulk stage, but the highest current charger I've seen is like 90 amps.

Is this correct?


Solar Enthusiast
What is the maximum charge current on your BMS? I've seen several 100a BMS that there charge current is only 50a


Solar Addict
You are correct when you are wiring in parallel and basically making your battery capacity twice as large - it will handle twice the rated charge current of a single one.

The amount of current you can supply in the bulk stage is usually dictated by just how large of a charger you can purchase. Choose one that doesn't exceed the battery specifications, like 0.3C or whatever it is you are using.