Swithin Serwadda

S Bengi wrote:Total Battery Bank = 7,200W
Discharge Capacity = 3,600W/day with the recommended 50% discharge
Discharge Rate = 10% of Total Battery Bank = Charge Rate =  Solar Array Size = 720W or 750W
Recharge Capacity = 3,000W/day = 750W Solar Array x 4hr/day = 3panels x 250W/panel x 4hr/day

Now to answer your question. Technically you can combine the 200AH and 100AH batteries safely, but I don't recommend it due to significant losses.

Thank you. I hadn't mentioned that all the batteries are gel. Nonetheless I will go with the general recommendation not to combine them.

Jeremy Baker wrote:This article explains some reasons why it’s not generally good to mix batteries. In general uniformity is good with solar energy systems. You may get a little use out of mismatched battery but it’s life will be shortened.
https://gridsub.com/can-you-mix-different-ah-batteries/

Many thanks Jeremy!

Matt McSpadden wrote:Hi Swithin,
I don't have enough experience to guide you on the specifics of setting it up, but I would highly recommend a charge controller. They are designed to help charge a battery bank evenly and some other things to help prolong battery life.

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Hi Matt,
Thank you for your response!
There's a 50Amp MPPT controller. The issue is: Is it okay to wire the 2 smaller batteries in parallel (to make 200Ah) and similarly the 2 big batteries (to make 400Ah) AND finally connect the two banks in series? Won't the capacity difference cause problems?

Hi good people!
I have two 12v 200Ah batteries + another two 12v 100Ah batteries, 3 solar panels each rated 24v @250w and a 50Amp MPPT controller. (Each of the larger capacity batteries came with a panel. The third panel is for the two smaller capacity batteries). The panels are currently wired in parallel.

Considering the Ah differences, can I utilize ALL the batteries in a parallel/series setup that gives me 24v?
If so, what configuration do you recommend that would ensure balanced charging?

Many thanks