Random Voltage Fluctuations.

[RGOLD]

Just noticed that randomly the battery voltage on the C7 display drops sharply about 1.4V - 1.6V while riding. For example, power level is constant at around 2 bars on a flat road, the displayed voltage is stable 48.9, suddenly I notice the voltage drops to 47.5, 47.3 then it's going back and stabilize at 49.8. The power assist level stays the same.

Has anyone notice this?

 

[jkvt]

That seems a little extreme. I've seen small fluctuations when the PAS is pumping a consistent voltage, but usually anything on the more extreme side is right after the PAS goes from full power to nothing. I think during that massive drop in power the sag is always less than 1V and generally 0.5v or less. May be worth letting the battery drain mostly before you charge it up and then let it charge all the way back up. Maybe let it trickle for an hour or so after? I know with LiPo batteries it is super important to be careful to balance charge properly. I'm not sure if these lithium ion batteries are better at just handling that themselves. If they can go out of balance though I'm not sure that would cause what you are experiencing but it would be the first thing I try to rule out since it's simple and out of balance probably does cause weird things.