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Hey all. I have a acquired some Li-NMC cells for my EV project out of an E-golf. I am excited to switch from my current lead acid set-up.

About the cell :
Manufacturer : Sanyo/Panasonic
Nominal Cell Voltage: 3.6 V
Maximum Cell Charge Voltage: 4.1 V
Minimum Cell Discharge Voltage: 3.0 V
Capacity: 25AH


I want to bottom balance my pack first. Most of the info I am finding is for LifePo4 cells which have different characteristics (specifically voltages).

So for these cells, what is the voltage that I should discharge each cell to?

3.0 V?

For charging - what is the max voltage I should charge to?

I plan to only charge to 80%. I was thinking the range from min to max ( 3v to 4.1 v ) is 1.1 volt. Therefore 80% of 1.1 volts is .88volts. Therefore charge to max 3.88 volts per cell.

Or is there a better formula?
 

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NMC cells do not really require any Top or Bottom Balancing, thus why no EV manufactures would allow you to do either.

When it comes right down to it, only LiFePo4 cells need Top or Bottom Balance because the charge/discharge curves are so dang flat, SOC cannot be determined by voltage. NMC cells have nice SLOPE Charge/Discharge Curves and can be easily Mid Balanced. Just connect all cells in parallel and walk away for a day.

Charge to 4.2 vpc and disconnect at 3.0 vpc. Just do not go over 100% SOC 4.3 vpc, or lower than 5% SOC @ 2.5 vpc. Nothing could be simpler. KISS! Make it complicated, and you make it prone to failure.
 

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These cells are pretty much empty at 3,5V, so you can set that at 10%, 4,1V is good charging voltage.

you can use the original bms coupled to Tom de Bree's 'SimpBMS' (see classifieds).

balancing: check if all (4s and 2s) modules are the same voltage now, than you have a good start.
 
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