'85 stalls when headlights are turned on

The car runs fine until I turn the headlights on. In less than 30 seconds, the engine stalls. When I turn the lights off, the car will restart and run normally. Any ideas? Thanks, WES

That sounds like a battery problem, but, then again, you do not need the battery to keep the car running. I have an idea (just an idea, not certain) that the negative feed could be incorectly grounded and it creates a power surge or something like that.