I’ve had 9 of these for over a year. I have never once seen some sort of average decline from day 1 to day 100, 100% to 0%. (Their batteries last 96 days for me, on average.)
I’ve always seen them do weird things. They mostly stay at 100% a long time, then drop down, probably to 50%. And when they fall below 50%, they die within days. A kind-of typical pattern is to be at 100% until day 75, then drift to 50% for a week or two. Then a day of 40%, then dead.
But I can’t describe all the oddities I’ve seen; 3 months X 9 = 36 graphs. One sat at 1% for weeks before dying.
I have logs if there are specific questions, but it’s a chore to summarize.
I can’t rightly explain this except to think that there is some super simple testing of battery strength.
Hoping some microelectronics Electrical Engineer can chime in?