I'm trying to sort out my inverter and battery wiring and need some advice. Here's what I have: an EG4 6000xp inverter, three Lifepower2 48v 100ah server rack batteries, and two bus bars rated at 150 amps each. Currently, I'm using 1 AWG wire as per the inverter manual to connect the inverter to the bus bar, and 4 AWG cables for the batteries. The cables are quite short since they were made for a specific EG4 server rack that I don't have. I want to reposition the bus bars for better safety and organization, which means I'll need to buy additional wire.
Now, I noticed when I check the EG4 monitor, the charge and discharge amps are pretty evenly split across the batteries. For instance, discharging 167 watts results in a total current of around -3.6 amps, which looks like about -1.2 amps for each battery. My question is this: given that the maximum amperage for the inverter is 140 amps and the load seems spread equally across my batteries, can I use 6 AWG THHN wire to connect each battery to the bus bar? I believe each connection will only handle around 47 amps. Additionally, if one battery fails, would that mean the remaining batteries would take on more load and potentially exceed the wire's rated capacity? And why did the batteries come with 4 AWG wire if they can't handle the full load?
2 Answers
You can technically use 6 AWG, but I'd play it safe and go with a wire that can handle more current. Ideally, each battery should be able to supply the max output of the inverter — so sizing the wire to accommodate that makes sense. Make sure all wires to the bus bar are the same length and size to keep everything balanced. In this case, I would suggest using 1/0 wire for the best safety and efficiency.
If you're not planning to fuse the batteries individually, stick with a heavier gauge like 1 AWG or even 1/0. If one battery shuts down, the others will get overloaded, and that 6 AWG won't be able to handle it, which could lead to overheating and a potential fire hazard.