Chosen Solution
When it is full charge then I use it, the battery percentage stays at 100% for a while like 10-20 mins of usage then it goes to 99%, but the problem is when it is now 99% then I lock the phone and not use it for about 1 hour, the battery percentage drops to 87%, and then I used it a while again like 3 mins and it drops 86% then I locked it again and not use it again about an hour it drops again to 77%. It’s like everytime I use it for a while and locked it and not use it for a while, the battery percentage drops extra 10% or more. But when I use it straight I get the desired usage of 1hr30mins to 2hours of gaming. The problem is just when I lock the device after using it for a while, then I leave it for an hour, it drops extra 10%. then it slowly drains like it is normal in standby after it drop that extra 10% or more. It is also in airplane mode without wifi and bluetooth I already check the usage in battery but there is nothing to be draining the battery between that percentage drop. iPhone 5s, iOS 12.1.2 Newly Replaced Battery, 100% capacity, 32 charge cycles. I already recalibrated the battery many times, reset settings, restored as new, but the problem persists. So is it in the battery or in the iOS? Is it possible that a newly battery behaves like that? or it is just the iOS 12?
There’s a chance the battery you just installed is defective but there’s no way to tell for sure without an alternative battery to try. There’s also the possibility that the phone itself is faulty, maybe a short somewhere or a failing chip..symptoms you describe would be coherent with all these possibilities. The easiest step would be to get a different battery from an alternative vendor to see if the problem persists.
