My iPhone 4 is drained within 3 hours with no use.
It gets hot and dies.
Check your apps that could be running in the background i.e. e-mail, Pandora radio etc. Take a look at this link, http://www.iphonestuffs4u.com/iphone-4-battery-life/
Read the article above and follow. If appears not meeting the battery specs listed then:
Restart phone. Test.
If persists, Restore as new. Test.
If persists, call Applecare, explain what you did and arrange a battery replacement.
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