Both of my friends has their alternator die suddenly in one day...mine seems to be dieing slowly. Ill be sitting in traffic, and I can watch the battery needle drop..it drops into the red zone often. Its better when I put the car in park. I tested the battery with car off and it was about 13.8. So I turn on the car and let it sit for about 2 min with the air on, and it drops to 11.8 and slowly dropping. Sound like alternator?

Oh yea, I have an underdrive pulley, and I know that hurts recharging, but ive the car for a year and its been getting worse the last 3 weeks or so. Also when the needle is dropping, it starts to idle a bit rough. If I rev it, it will shoot back up for a second, and then drop back down(battery needle that is).

Thanks

 

Sounds like an alternator.

The same thing happened with my friends 95 ta. For a week before the alternator, the car had the same symptoms. It died one night driving down the road. The lights and all electorinics died and he was just barely able to make it home.

 

Or it could be that it's not turning fast enough to generate adequate voltage so it shuts itself off untill the rpm's reach the proper level. Underdrive pulleys can cause that. Does it work ok when your driving or do you have the same symptoms?

 

I agree. That sounds like an alternator to me.

 

Make sure the stud on the back that wire bolts to is not loose.....if it is you can take the alternator apart and fix it.....that was what was wrong with mine when it was doing what yours is.

 

When I am driving, the car is fine...it recharges back up...sometimes when it gets really bad it wont recharge up to what its supposed to, it'll float around 13 or maybe less. Also heat seems to make it worse, like its worse during the daytime in the sun, but not as bad during nighttime.

And what kind of bolt do you mean...the one in the back that the ground bolts onto, that stud? Ill go see if its loose....

 

That's a positive battery cable on the back of the alternator, not a ground. Even stock, the alternator has just enough "umph" to meet power demands at idle. When you slow it down with an underdrive pulley, it only makes it worse. When it gets to a certain rpm [low], it might not charge at all.

As your battery ages, the reserve capacity diminishes. The reserve capacity is how long it will provide good voltage without being charged. You will usually see this stated on the battery specs along with the cold cranking amps (CCA). If your alternator has not been supplying high enough voltage over a period of time, this can contribute to the battery reserve also getting lower.

This may be why you see the "slowly dying" scenario.

IMO, I have not seen that many good reasons to use underdrive pulleys. Power gains are minimal and the effects of lower voltage can be critical for fuel pressure and spark output, not to mention powering all your accessories. Think about it when you are in bad weather and you have on high beams, defroster full blast, rear defogger, wipers...that's a lot of juice needed.

 

Same thing happened to me.


Also, what ShoeBox said, if you do a lot of city driving and a lot of idleing time it will eventually drain your battery down. Especially during the winter months when you are using your lights more due to the lack of daylight hours. I know when I drove mine during the winter months I swapped the under-drive pulleys back out.

 

From a little exp. and reading knowledge, usually the alternator just ups and takes a crap on you. Your problem sounds like a battery fixing to take a dump. That's what my car was doing. Slow cranking in the morning, throughout the day all was ok cause the alternator was feeding it apples. But no nutrition during the night and the battery finally said FU!

 

I don't mean to lead this thread in another direction, but I am having some of the same problems. My alternator died and took the battery with it. I replaced the alternator, and recharged the battery, and since then I've had this problem too. My question is, did the old alternator going screw up the battery enough so it needs to be replaced? The alternator has been tested and does recharge.

 

quite possibly.

 

I know I have said this before, but if the battery is dying, it puts a strain on the alternator. If the alternator is dying, it puts a strain on the battery. This is why a lot of times you end up replacing the opposite item shortly after you replace the first item.

 

When mine died, it was either fully on or fully off. I took it to AutoZone to have it tested and 2 of 3 tests said it worked. That third one though was the killer. And it did that repeatedly. Just get a new one so you dont have to worry about getting caught on that every 3rd time you drive your car it dies.

 

Had autozone test both alternator and battery. Battery needed to be replaced. Got a Diehard Gold, and it runs great now. Thanks for responses guys.