How can you tell if a car audio capacitor is bad?
 

Car audio system - 2 550 watt amplifiers, 2 10" subs, 2 250 watt 6x9s, 1 .5 farad capacitor, upgraded battery and alternator. After installing the capacitor according to the manufacturer's wiring diagram, I find that the car battery is draining while parked with the system turned off. The amps are powering off, the only apparent cause is the recently added capacitor. After removing the cap from the system, the battery drain appears to have stopped. Is this normal for a capacitor to drain the battery under these conditions, or could it be malfunctioning?