iPhone 6 battery drain after battery replacement

[Ankush Pandey]

So, i ordered an iphone 6 battery from amazon and replaced it properly without any damage.
Everything went perfectly but after a few days the battery started draining VERY fast. It loses about 50% in an hour.
I checked the battery capacity using different tools and they all say that battery is at 100% capacity.
I even did the geekbench test to see the performance and the performance increased to the new iphone 6 level.
I'm currently running ios 11.2.6.
Tried everything from calibration to complete restore. Nothing works!
What to do?
PS: Also, I'm not able to see the battery usage statistics since replacement.

 

[Just_Me_D]

Either reset all settings or restore your device and then set it up as new.

 

[Ankush Pandey]

Already done it. Nothing!

 

[Garz]

Maybe because it’s a battery from amazon?

 

[Ankush Pandey]

Maybe because it’s a battery from amazon?

but upon checking it says the battery has 100% capacity.
Does that not mean the battery is fine?

 

[Ledsteplin]

There's not really any way to see your % capacity, or battery health, in an app. Apple no longer offers that info to developers. So it's probably not that accurate. They're guessing using whatever they can. Try swiping out battery hog apps in multitasking, then a hard reset (reboot).
I read a review on Amazon, where someone purchased a new battery, then checked the charge cycles. It showed over 250 cycles had been completed.