Ip5 shuts off at 20% battery every time

[silroc]

Since ios7 this happens

Gets to 20% and boom, turns off

Try to turn on, but low battery image comes on

Put in charger, turns on and shows 20+% immediately

Rebooted, and tried different settings but no dice

Wiped and restored as new, same issue

Any thoughts? Is this common or rare?
Thanks

 

[sammy-boy]

Could be a faulty battery or one that's on its way out. Is it under warranty?