A handful of times in the last month, I've noticed the voltmeter drop to a little less than 12 volts. All but once, it was when I started the car cold. It would stay low for several seconds, then jump to normal. The one other time, the car wasn't warm yet, I'd just turned a corner from a stop, voltage dropped about 11.5 for about two seconds, then came back.

What does this sound like? Loose connection at the alternator?

Could be some belt slippage. Those are the symptoms of lowering voltage output if the alternator rpm drops momentarily. But it wouldn't hurt to check all connections. Or there may be something loading down the electrical system momentarily causing the battery/alternator to droop voltage for a few seconds.

I might have found the problem. I'm using the top post of my Optima instead of the side terminal. I was a doing the Big 3 last night and found that the post ring or whatever it is called cracked where it stops being round and protrudes for the bolt, if that makes sense. Could that cause momentary voltage drops?

i would have to say ya.....the battery needs gooc connections


got pics of the Big 3?

I'd have to say yeah, maybe a high resistance connection. You can replace that terminal. Remember also the posts are tapered & that the battery cables (clamps) only fit one way. The pos. & neg. posts are also different diameters aren't they? Its been a long long time since I worked on a battery with top posts..

I think the cracked piece has something to do with it. Any way you can fix that or is a new battery needed?

I've seen dropouts from battery posts cracking on the INSIDE of the battery before. That was a real stumper, so I'd say this is a big possibility.

I replaced the cable Friday. The problem hasn't returned... yet.

Yep, did it again. When I started the car today, then later as I was doing a little WOT "shift test". I've gotta have a loose connection somewhere, but I can't figure where. It CANNOT be the alternator to battery, or battery to ground, I've redone those.

How old is the battery? The problem is most likely the battery or alt. If the battery is more than 3 years old I'd start by replacing that.