Odd battery behaviour
I bought a refurbished iPhone 12 last week which apparently had a brand new battery fitted.
Particularly over the past few days I've noticed some very odd behaviour in the displayed battery life.
Below are two screenshots. In the first, I left the device charging overnight. When I viewed how the battery had charged in the morning, it had spent most of the night not charging, before suddenly shooting up to 85% over about half an hour and then not charging any further.
In the second screenshot, I used the device quite a bit over several hours last night during which time the displayed battery percentage did not drop until it reset suddenly itself to 32% overnight. I have then had it on charge again this morning, during which time the displayed percentage has dropped to 30%.
Any ideas what is going on?