Getting electrical advice at auto zone is like getting brain surgery at the drug store. There's a reason those mouth breathers are selling parts instead of fixing cars at four times the pay rate. If you're not comfortable doing your own diagnosis, let me strongly advise finding a real electrical professional who can find the problem. DC generators aren't complicated, but it's absolutely essential to do some basic diagnosis.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!