Charge rate in a serial string
I'm using 4, 12v AGM batteries in series to make a 48v string (with two strings in parallel, so 8 batteries total). If a single AGM battery is rated by the mfr to accept 12v 10A charge current, since I have four in series, am I still limited to 10A to charge that 4 battery string?
I know that since I have a parallel bank of two strings, I can charge the bank with 20A and not exceed the mfr's recommended charge rate, but I wasn't sure if charging current changed because of having 4 batteries serially in each string. Since Ah capacity doesn't change with batteries in series (but Kw capacity does), my gut tells me that I'm still limited to 10A charge current per string.
I've configured my XW6048's internal charger to only push 25% of its capability from the grid to my battery bank (but I usually keep it disabled anyway), based on my gut of 20A total charge current allowed to my batteries, but deciding what to adjust my SCC to--or if I need to at all--is a bit harder. Since my batteries are usually already topped off and in Float by the time the PV starts making significant harvest, I'm not too worried about day-to-day operation. But if the grid is down and my batteries are depleted, when the sun comes out, my PV is capable of providing about 45A to my battery bank, which would be more than double the mfr recommended rate--if my gut feeling about the 10A limit per string is valid.
XW6048, 3.4KW PV, Grid-Tied, always tweaking.