monitoring batteries in parallel.

[Kelly Fyfe]

Hi there, I have 8 Nissan Leaf batteries in parallel in my offgrid system. Each battery is a 2.5 kWhr pack for a total pack size of 20 kWhr. Recently I have noted that one of the packs is absorbing 2x the current as the rest which to me is signalling a problem. Each 2.5 kWhr pack has its own BMS (no bluetooth). I have a Emporia energy monitoring system for my house AC, but in talking with them they only do AC at this point. I'd love to have an "Emporia like" Battery monitoring system but cant find one.... any thots?

 

[time2roll]

I would be thinking to pull one battery off at a time to do an separate capacity test.

 

[MisterSandals]

I have 8 Nissan Leaf batteries in parallel in my offgrid system.

Exactly how are these wired in parallel?

They need to be wired in a balanced manner so they receive the same current charging and discharging.

 

[Kelly Fyfe]

they are wired straight from the positive and negative bus bar.... they are as balanced as I can make them.

 

[Kelly Fyfe]

I would be thinking to pull one battery off at a time to do an separate capacity test.

Exactly but hoping for a more "online" solution with continuous monitoring...Volts and current in and out of each one.... there's gotta be a more 21 century solution ????

 

[MisterSandals]

they are wired straight from the positive and negative bus bar.... they are as balanced as I can make them.

Equal length + wires from each battery and equal length - wires to bus bars?
Extra credit for offsetting wires from bus bars to loads/sources.