Probably nothing, I rode my e2 last week and charged it up to 100%. Had a play about on it and it dropped to 97%. Doing a big ride tomorrow so thought I’d charge back to 100%. For some reason no matter of charging will increase it back to 100%??
It'll only recharge once you get below 95% ( I did the same thing a few months back, nothing a few minutes riding up / down a hill on full assist couldn't fix)