Safe voltage range for 21700


I’m going through the process of deciding the finer details of a Molicel p42a pack build, I was wondering what people’s thoughts are on a usable voltage range.

I like the idea of treating the battery well to enable safe and long use.

What do you set your voltage cut off at (per cell)?
What voltage do you charge to (per cell)?


4.15 / 3.0 ( under load)

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You can also go up to 4.2V but it will not add much capacity. I set my VESC Battery Voltage cutoff End to 35.6V on 12S, so 2.96. I used it for quite some time now. No problem, as long as you keep them balanced. You can always add LiPo beepers to get an alarm if a single cell is below 3.0V (if you discharge without BMS). Even if you discharge a row to 2.8 or 2.9V under load, it will recover to 3V without load. Balance charge to storage after each ride.

4.1 or 4.15 normal charge, if i plan on a maxed trip 4.2V

Cutoff at 3 (under load)

Thanks for the replies, it’s very useful.

So when it comes to usable capacity I might expect about 3.9ah out of the 4.2ah per cell when charged to 4.15v and drained to 3v?

Depends on the current you draw. Max I could get out of my 12S8P pack ist 1250Wh of a theoretical capacity of 1382Wh, or 90%.