I've got a new optima battery and I bought a new alternator and I thought the problem would be solved. I was having a problem with the wire from the +cable to the batt getting real hot and melting but bought a new alternator and that problem was solved, but it still wouldn't hold a charge so I got a new battery because that battery was bad. But now something is still draining my battery. It stayed charged for a day and a half. But now the new battery is drained, what could this be?? Could it be something with the lights because when i turn my lights on my tach doesn't work and soon as i turn the lights off my tach comes back on. It's a 75 impala with a 350.