Do a voltage drop test, checking every connection from the battery to the engine and back. If you don't know how to do that, we can't help you at all. Find a good mechanic who knows how to use a voltmeter.
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!