I'm working on a solar project using eight 12V 104Ah Solar Extender SLA batteries. My plan is to connect them in two strings, each consisting of four batteries wired in series, and then parallel the two strings together. I'm starting to worry about how to balance the batteries because I've heard that balancing 12V batteries in series can be tricky. I ordered an Eco Worthy battery balancer, but I'm unsure if I need to use one balancer for both strings or two balancers, one for each string of 4S. The balancer's diagram shows it being used with 8 batteries, which adds to my confusion. Any advice, especially with diagrams, would be fantastic!
2 Answers
The diagram you found is correct! Don’t stress too much about balancing your batteries; it's pretty rare for them to go out of balance. Modern batteries usually balance themselves, and many have built-in BMS protection. Using 4x 12V batteries to make a 48V setup is totally fine—it's just like a larger 48V setup with 16 cells anyway. You're good to go!
You’re correct about the Eco Worthy balancer's design. While it shows 4S2P, it balances two batteries at a time within that setup. The best approach is to set up two groups of 4S SLAs. Each set can have its own balancer. This way, you’ll truly balance each battery individually, so consider getting another balancer for proper management. It’s confusing that they show a diagram for 8 batteries because it can be misleading. But running two balancers is definitely the way to go!
I was thinking that too! It's odd they don’t specify using one per series. Makes it harder for us to figure it all out.
But remember, these are SLA batteries without a BMS, so just keep an eye on their condition!