I recently discovered that it's possible to connect batteries of different capacities together, and I'm curious about how it works. Currently, I have 2 EG4 48V 100Ah batteries set up in parallel with an EG4 3000 inverter, and everything's functioning smoothly. I also have a LiTime 48V 60Ah battery that lacks communication capabilities just sitting around. My question is, can I connect this LiTime battery in parallel with the EG4 batteries while retaining communication with the inverter, making the extra battery just an add-on? Or do I need to change the settings to a user-defined battery type and adjust all the specifications?
2 Answers
I'd recommend against it. Mixing batteries of different capacities, even if they're the same type, can cause problems. LiTime’s guidelines warn that the mismatched capacities lead to different internal resistances. That can result in the larger battery getting overcharged or overheating, while the smaller one might not charge properly, risking damage or decreasing lifespan. It's just not worth the potential issues—stick with batteries of the same capacity in parallel.
Yes, you can connect it in parallel, but there are some caveats. When you add a non-communicating battery like the LiTime, the inverter will rely mainly on the info from the EG4s, which might misrepresent the total capacity. So the state of charge (SOC) numbers could be off. You might need a separate shunt to keep track of the SOC accurately, as the total capacity will appear to be less than what it actually is. Just remember, the inverter won't reflect the full 260Ah—you'll need to manage that awareness yourself.