diy solar

diy solar

Is it necessary to balance new batteries?

Oceansailor

New Member
Joined
Jan 1, 2021
Messages
4
Received brand new Lishen 280 Ah batteries. The Voltages on each cell are very close
Cell1 3.2949
Cell2 3.2956
cell3 3.2957
cell4 3.2957
Therefor max difference 0.8 milli Volts
They are rated 3.29 Volts. I am waiting for a load/charge tool. Has not arrived yet. Can I connect straight to the JBD Smart Interface?
 
Yes you need to top balance them.
Typically the penultimate step of the production process is a capacity test test to 2.5 volts per cell.
The final step is to charge them to ~3.29 volts.
That means the cells are effectively bottom balanced.
BTW top balance is imho a bit misleading.
All that is required it to charge each cell to 3.65 volts as measured at the cell terminals.
That way your battery will have the capacity of the weakest cell which is as good as it gets.
 
Last edited:
Those voltages are very close, but since they are LFP cells in the middle of the charge curve, you really don't know how far off the true state of charge is. The voltage curve in the middle of charge is so flat on LFP cells, that you even the same voltage could be 10% different state of charge. But since they are that close already, it makes the job of top balancing so much easier. Wire all 4 cells in parallel and charge up to 3.65 volts and you should be good to go.
 
3.29 can be 40% capacity on one cell and 70% capacity on the other, balance at the top or bottom, as the voltage curve in the middle is very flat on lifepo4
 
Back
Top