Comment 7 for bug 1540062

It's normal for voltage drop off to accelerate below 3.6v (or 3.7V, depending on the battery). The voltage discharge curve looks normal for lithium ion. However, the capacity graphs look like a pretty poor method of converting voltage into a percent.

I find that the kernel's reported voltage usually tracks the actual voltage pretty closely, but the capacity estimation lags way behind. This is harder to measure on krillin since its kernel doesn't report voltage.

In any case, I doubt it's hugely important for the reported percentage to be totally accurate. It's more important for the voltage to give timely and continuous feedback about the battery state, with no large sudden jumps. Being reasonably accurate likely only matters near the top and bottom of the scale.