or your terminals were loose and dirty. and remeber to start the car with the lights off, and dont sit there and listen to the radio for hours with the car off. i actually had a fun time with my accent the other day. my car would be driving fine and wonderful, and then the lights would get bright as all **** and the radio caught on fire. so, i take the alternator off and have it tested. teh moron says "oh its fine" put it back on. same thing happens, lights get hella bright (radio is gone now because it smoked and such and is broken) so i take the alternator back off and say "test it again, this time test the voltage regulator" and the guy goes "oh yeah, well, the thing isnt stopping output when its supposed to." so.. yeah, the regulator was giving full output all the time, which means i was seeing 16+ volts intermitantly. its a good thing hyundai ECU's have an extra voltage regulator in them, or i would ve very angry