iPhone 7 wrong battery percentage after battery replacement
I have recently had my battery replaced in official Apple service. After few days I recognized a weird issue. Battery drains really slow from 100% to 20% then when alert pops up that it has less than 20% of battery left it drains in seconds to zero or even worse it shuts itself off on 17% depending on how I use phone. For example it can not stand video or audio call when under 20%! Weird things are sometimes I can turn it back on, sometimes battery logo pops up and it takes time to turn it back on. I tried battery calibration few times, but the same issue remained. Another weird thing that came with new battery is an issue with charging. When I plug in charger it starts to drain battery for 1-2% then it refills again and it charges on same percentage for about 10 mins then it charges normally up to wished percentage.
What I noticed is that it shows me wrong battery percentage, when I restart iPhone it shows “real” percentage for 1 second which is always lower then “fake” percentage.
When I did battery calibration I did not know how to drain battery till it’s completely empty, I even left it overnight to drain further, then fully charged it and reset iPhone when on charger.
I also did DFU restoration of my iPhone, but no luck...
anyone facing the same issue? Could it be the battery issue? With an old battery I didn’t have any of this problems.
PS. Battery health is 100%
iPhone 7, iOS 14