sprint vs tmobile battery life

[xxhtcevoxx]

so im totally baffled by this

I have a s3 from sprint and battery life is decent , my gf has a s3 from tmobile and battery sucks! it will charge over night and show 40% or when its at 100% one post on fb , phone call and few texts and battery is down to single digits. and it was a brand new battery , first full charge too, so i took the battery out of tmobile phone that was allegedly at 4% and put it in my sprint phone and low behold its at 80% !??!!! so what in the world is going on??
i made the settigns all the same on both phone, and tmobile just sucks the life out of battery just by sitting there
any ideas? what can i do? is the tmobile s3 faulty and needs to be replaced? this is crazy
just few weeks ago we went camping and both phones were in airplane mode as there was no cell signal and we were using both phones as cameras , needless to say i have 100s of pics on sprint phone and only a handful on tmobile

any help with this would be greatly appreciated
thank you

 

[GTWalling]

I would say if you put the T-Mobile battery in your phone and it showed 80% then the gauge on the T-Mobile phone is off. Try turning the T-Mobile phone off and charge it to 100%. Unplug the charger and then pull the battery for about a minute. Now put battery back and start the phone. Let it run for several hours and see how the battery does.