I hate electrical problems.... charging

no, its not a drain. i put a voltmeter up to it and found a 3 volt drain. but then disconnected my hot wire to the radio and it went to zero. Its just the hot that keeps all my settings on the radio that pulls juice. nothing else. the thing is also, i can be driving over an hour, and when i shut it off to fill up with gas or something, its dead or very close to it when i try to start it back up. thanks for the suggestions tho guys