Battery Issue - percentage shows low but plugging in makes it go way up. What could it be?

[iMore Question]

Battery Issue - percentage shows low but plugging in makes it go way up

I'm having some issues with my battery on my Iphone 6. It appears that the battery will drain quickly (like 50% in 2 hours with normal texting usage) and then as soon as I plug it in the battery percentage shows an increase of over 25% or more.

Help?

 

[Ledsteplin]

Re: Battery Issue - percentage shows low but plugging in makes it go way up

Welcome to iMore! It may just be the % indicator in the status bar. Try calibrating it by letting the battery discharge down to 1%. Then charge it up even past when it first shows 100%. Don't use the phone while charging. See if that helps.
If you're concerned about the battery, you can test it with this test.
Battery test
Write down your usage and standby time, press the sleep/wake button (or lock button, as some call it) to put the device to sleep, and set the device down for five minutes. When you come back, take note of the change in time. If your device is sleeping properly, then the Standby time should have increased by five minutes and your Usage time by <1 minute. If your Usage time rises by more I one minute, you have a drain problem. Something is keeping your device from sleeping properly, significantly shortening the time it will last.