My first thought is the battery even though it tested good. Intermittant problems can occur with a battery. If it is orginal, get it replaced first.

James

After more thought, you need to have a voltmeter hooked to the battery when you suspect the problem is happening. Chances are greater that the battery is defective rather than the alternator. But if you run it this way long enough, you could burn out the alternator as well due to the overload caused by a shorted battery.

Also, be sure to wear safety glasses when working around any battery, especially one that could have an internal short. Been there done that, not fun.