Phone shows low battery when fully charged

[Dude3812]

Having a problem with my wife's droid. It shows that it has a low battery when it's fully charged. If she reboots it goes back to showing correctly.
This doesn't happen very often, but it did happen with the phone at stock and rooted with custom rom. Since it has happened with both, I'm assuming this might be a hardware issue. I wanted to see if anyone else has seen this and might know if there is a fix.

 

[Sandso9]

My dads Droid does this its stock and after a full night charge some days it will show 5% in an hour

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