IMO 3.3V open circuit (after resting) is going a bit emptier than you’d want to for most applications. It shows the state of charge is really <5%. I know we want to get the most flight time out of the pack but that’s not great for the lifespan, and it means you had really no reserve.
At 3.0V I’d start to consider the cells are at risk of damage.
That said I don’t know exactly what cells are used for the SP140 - anyone know?
Why is 1 group lower? It’s probably just the one with the lowest capacity, and the cells are “top balanced”. The BMS should have cut off discharge based on this group. Generally you do see more spread in voltage at “empty”, although the rest are really tight, as you can see the voltage takes a knee at that level of SoC so a small difference could explain it.
What Bratwurst said is worth checking though - if you did have one cell disconnected it would show up like this, although it should not be able to happen and would be a major issue by itself.
From ShieldSquare Captcha