How is incoming charge distributed amongst multiple batteries wired in parallel?
July 27, 2009 4:03 PM Subscribe
Say I have a three batteries (all 12V SLA of the same Ah capacity) wired in parallel to form a bank. I connect a dumb charging source (let's say 12V, 5A). How will the incoming charge be distributed amongst the three batteries, and what does it depend on?
I'm keen to understand the principlesat work here. I've built several battery banks (largest was eight deep cycle marine batts), so I've done a fair bit of just plain trying it out. I'm not trying to enhance my theoretical understanding, so I can figure out what will happen in a simple situation like:
Battery 1: 100% charged
Battery 2: 50% charged
...Battery 2 will receive more of the incoming current. But how much more? Will it receive 100% of the current, with Battery 1 receiving 0%? That's my guess - and in fact I'm guessing that Battery 1 will be charging Battery2 in this situation, and they'll end up equalizing then charging in parallel.
If I'm right about that, how do I generalize to:
B1: 100% charged
...I'm guessing B1 and B2 will charge B3 until B2 and B3 equalize, then B1 will charge B2and B3 until all three equalize?
What are the key factors at play here? State of charge of the batteries has to be the main one, but... well any help appreciated. I've googled for info, and read the basic battery faqs, but none have helped me understand this.