My 92 Honda Civic battery is dying all the time, I've started the car and took off the battery cables to see if it was the alternator But it continued to run for about twenty minutes with lights, heater, and music on. So I guess I don't know if the alternator is working and not working, because I haven't known alternators to do that

 

Disconnecting the battery with the engine running can potentially damage sensitive electronics. Instead, use a multimeter to make voltage readings across the battery posts or take your car to an auto parts store to have the alternator tested.

 

Autozone can test your battery and alternator at the same time. If not with the car running hook up you multimeter and it should be reading a min 13.8V with the everything on.