strange reoccurring problem in my 93 ranger; when i turn the headlights on, the volts drop and the engine dies,

i cleaned the terminals and replaced the headlight switch/dimmer the last time it happened but this time i can't diagnose it, alternator? battery? Fuse? relay?

battery is kirkland, from 2010 but always starts healthy and doesn't die other than this, any ideas greatly appreciated thanks.

Dirty negative on ground to chassi?

Could be? I'll check that out, thanks.

Go to autozone and get the batt/alt checked

Got it checked at the local auto store and the alternator and battery read fine, and the headlights didn't kill the engine, I'm guessing it was a just a bad connection? Really appreciate the replies thank you.