Battery meter`s first strange result

I started charging OP1 two days ago when it was on 2,5 lights. Id been charging switched off device with usb power adapter for more than 10 hours untill lights disappeared. Than checked it and there were still 2,5 lights.<br>Is my battery dead? Or its just randomly working battery meter?
I did full discharge two years ago and then charging results were Ok until now. So what`s happened?
I am using OP1 not often. Maybe long down times killed the battery?

ive had similar issues. running the batt dry/factory reset usually clears it up.

USB connection with PC solved this problem)