your radio should not be causing a 3 volt drop on the battery..........If you have a full charge before taking off and nothing in a short while then possibly your alternator is bad when it gets nice and warm.
no its not dropping the battery 3 volts, i disconnected the negative cable and ran a voltmeter from the cable to the negative post and thats what it was pulling. just enough to keep the power button lit up and the memory.