ok, sounds like an alternator issue. Take it to a auto parts store and they should have the machine to test the alternator. You only use the battery to start the car, after that it all relies on the alternator. Either that or a short in the radio circuitry but from the numerous device issues I'd assume alternator. A multimeter would also be able to check it. make sure you're getting at least 14 volts when the engine's running.