JPhillips-998

I am guessing that this is an alternator problem but thought I better ask before I spend my certificate...

Drove for about 3 miles last night and the battery and anti lock lights came on. Still drove okay.

Had dinner, drove home and before I got there all the lights came on and the car quit? Clicking when I turned the key but needed a jump to get home. Died again in front of the garage and had to attach a battery charger to get it started again.

Anything other than the alt?

STLPCA

Dead battery. Did you/anyone check the battery? If car needs jump to start (battery has no juice) & then runs (on the alternator), why do you think it's a bad alternator?

JPhillips-998

The car started and ran fine for a while, so I didn't think it could be the battery. My guess was the car was running off the battery, not the alt., and that drained it to where it wouldn't run.

swftiii

Jeff - this sounds like a common theme with you and your PCars. It sounds like the alternator, but considering your source (me) I wouldn't put too much stock in that.

Good luck,

-Skip

Frank 993 C4S

As Dan said, it's probably the battery. I had the same symptoms and it was not the alternator.

JPhillips-998

The car does not get driven much. I'll throw a voltometer on the battery and see what's happening.

Greg Fishman

Jeff,
Check the belts also to make sure they aren't so loose that the alternator isn't turning. Not likely but possible. Also go to AutoZone or Advanced Auto for your alternator and you can get on for half what the dealer charges.

mike cap

Jeff,

The voltmeter won't tell you much about the battery condition. It could show 12 vdc or so at the terminals, but the battery needs to be fully charged then load tested at a shop to see if it is any good. If the car is low mileage and driven seldom, then the battery is probably sulfated and needs to be replaced, especially if the battery is more than three years old.

If you can get the car started and check the bus voltage with a digital VOM, the alternator should raise the bus voltage to between 13.75 and 14.25 vdc, depending on RPM (an easy spot to grab the bus voltage is in the cigarette lighter hole). If this is the case, you probably do not have an alternator problem. Then turn on a bunch of load (lights, a/c, fan, etc) and see if the voltage drops with all the load on. Should stay above 13.25 vdc or so under load.

I agree with the guys that it is probably a shorted battery.

Mike Cap
1997 C2
Arena Red

JPhillips-998

The battery is at 13.4v w/o the engine running and 12.44v w/the engine running at idle, no other load.

I left the charger on all night, so the battery should be fully charged.

mike cap

Jeff,
Sounds like your numbers are backwards. The battery voltage can't be above 12.2 vdc or so static. The 13.4 vdc sounds close at idle. Give me a call at the office if you need some help sorting this out. 800-333-0519 x 106.

Mike Cap

mike cap

Jeff,

Did you test the battery static just after charging and got the 13.4 vdc? If yes, then you may have an accurate measurement if it was fresh from the battery charger.

If you are getting 12.4 vdc with the engine running at idle and the battery connected, that is low. Load up the bus and see what happens. Rev the engine and see if it comes up as well. If the bus voltage continues to go down with the car running and load on the bus, then the alternator is not keeping the bus voltage up and the battery is carrying all the load. Then you are correct that the alternator probably has shorted diodes.

Again though, if the battery is more than three years old and the car doesn't get driven a lot than change the battery. Nothing kills a battery like sitting.

Mike Cap
1997 C2
Arena Red

JPhillips-998

Mike, I will check it again, but the 13.4v reading was w/o engine and the 12.4 was w/engine and no load...

JPhillips-998

Okay, here are the new readings all taken from the cigar lighter.

Off 12.82
At Idle, No load 12.36
Reved, No load 12.31
At Idle, Load 11.92
Reved, Load 11.89/11.90

mike cap

Jeff,

Your alternator or voltage regulator is not functioning. Your battery is fully charged and carrying 100% of the load. If you let the car idle with a full load on the bus, the voltage will continue to drop pretty quickly.

Voltage with a properly functioning alternator should be between 13.75 and 14.25. Maybe a bit lower at idle, but not much.

Do check your belts for tension as Greg suggested. Otherwise it's off to your service shop. Hve the battery replaced at the same time if it is old. Cheap insurance.

Mike Cap
1997 C2
Arena Red

Ray Calvo

I'll go along with your and some other's guess on the alternator or voltage regulator being bad, only because it happened to me on my old '84. Was out at Mid-Ohio for a driver's ed. On way home I stopped for gas. Car seemed to crank a bit slow but didn't pay much attention. On way home, as night came I turned on the lights. Noticed something strange as lights got dimmer as darkness got deeper. Just when I realized I had a charging problem the car just died. Never got an alternator/charging warning light on the dash. I left the car off for about 10 minutes; it then started up again and proceeded a few more miles before dying again. Needed a new alternator.

Looks like it's time to bring the car into a shop for an electrical system troubleshooting.