Electrical Problem

[lilmike2069]

OK.... I'm having an electrical problem again just out of the blue. Yesterday, I started up the car... pulled out of the driveway, and about 100ft later, it just completely dies. So i'm stuck in the middle of the street with it in park (in a non-busy neighborhood thank god) and I walk to my garage to grab my multimeter. I put measure the batt leads... it reads 12.4V or something like that. I measure JUST PAST the leads to the connectors on the leads of the battery and it reads like 10.5V. When I open the car door, it drops to like 3 or 5 Volts. So i'm like ok, dead battery or corrosion between the terminal and the connector. So I pull the + terminal and clean it and sand it down and reconnect. Still nothing. Then I get to the negative terminal... i notice it is just barely loose enough to be able to twist it. After I twisted it, car started right up. So i think, ok, i'll go get a new connector and make sure everything is tight as can be. So i did, and i didnt havnt had any problems with it today. I also checked the alternator by pulling the + cable while the car was running... it still ran... alternator good. Its also putting out about 14.5V so all good. But then I got to thinking... the car was already running when it died which means that it HAD to be something other than the loose ground cable right? I mean, the alternator would be filling that void and the alternator is good! So now I really dont know what to think. Maybe theres a loose wire somewhere that randomly creates an open circuit that I have no idea where to begin to look for since there are sooo many wires AND it has only died on me once. Its not like some recurring problem that I can easily test. Its frustrating. Any help?

[TLMNICK]

An even Slightly loose negative terminal on the battery will cause you to stall out. If the car is in full motion on the highway or something...you'll get away with it, but NOT in the streets. As soon as you tap your brakes, and all the lights in the back come on...it'll shut right down, because the alternator wont be keeping up at that point. A car doesnt completely run off the alternator at all times while you drive. Most of the cars accessories are run by the alternator, but the battery is needed for sudden demands for power (such as brake lights)...the battery is used to stabilize the power comming from the alternator....without it, you'll be bound to have issues like you mentioned above.
Plus, if your terminal was even a bit loose, that means that there was slight space between the battery post, and the terminal....the power arking between those two points puts a coating of "burn" (for lack of a better term) in between the post, and the terminal. Which is why, although the terminal was attached to the post....you werent getting any juice to the car.

[lilmike2069]

Hmmm interesting. I was kindof under the impression that the alternator was capable of supply sudden demands of 60+amps depending on the alt of course. I think ours are like 80 or 90 amp alternators. I should also mention that it wasnt on like Loose enough to were there was a gap and it was just flopping around.... it did take some force to swivel or twist it but I do think that theres more than just a coincidence that it started right up after I twisted it. I guess time will tell :-\

[lilmike2069]

Thanks for the info btw... hopefully you are 100% right and that is all that was wrong

[TLMNICK]

It wouldnt take a big gap to cause your issue. I had the same problem once with my cressida back in the day....i changed my terminals, and till this day, the car has never had that issue ever again.

No the alternator is not capable of that type of sudden current draw....its possible it might take it if the car was on the highway, but even then it'd struggle.