charging a battery bank of 24v

[justme1301]

hi i wonder if anyone can give me some help with charging a 24v batttery bank consisting of 4 x 12 130ah lead acid batteries joined series/parallel giving me 24v 260 ah
i have a mains batttery charger 24 v 65amp which if i did not get enough power from solar i could use to recharge the battery bank for use at nights in winter
so question is where on the batteries would i put tne poss and neg my way of thinking the rear batt neg and front batt pos so all 4 batteries will charge will this work and is it safe or can anyone tell me where to attach the leads from charger to battery bank, thanks very much for any advice
jon

 

[sunshine_eggo]

Batteries arranged in a 2S2P configuration.

ALL connections to the battery bank should be at the positive end of one string and the negative end of the other string.

You should also check that all 12V are within spec when bank is at peak system voltage.

 

[MichaelK]

Something I could add is the amount of solar needed for that sized battery. It's going to depend in part with the panels themselves, and the electronics you connect them to.

As a general rule of thumb, traditional lead-acid likes charging at ~1/8th of C. With your C = 260Ah, that works out to be 260Ah/8 = 32.5A. Since battery charging is going to start at ~25V, you'll want at least 32.5A X 25V = 812W of panels. Normally, I like to include a fudgefactor of 85% to account for adverse conditions, so call that 812W/85% = 955W. Call that four 240W residential panels.

You want a MPPT controller for that, with an amperage rating >32A. Take a look at Epever's Tracer 4210AN. Most 240-250W panels put out ~30V, so you want to wire your panels 2S2P. That is, two parallel strings of two panels each in series.

Keep in mind that that wattage is going to work really well in a place like sunny California, where I live. In the UK, you are likely to need more to compensate for the cloudy days of winter.