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alternator and battery voltage

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want_a_gsx

15+ Year Contributor
257
3
Apr 3, 2006
Milwaukee, Wisconsin
ok so i just got the alternator replaced and i am still getting a little annoying problem.

everytime it rains (and i am driving in the rain), the voltage seen by my SAFC goes from 12.8-14.1. like if i am giving it gas, the voltage is fine, but once i press the clutch down, about 3 senconds later, the voltage goes down to 12.8 V.

anything i can do about this?

is there a way to cover the alternator so it doesnt get wet?
 
The only times my alternator has got wet is when I didn't have the wheel splash shields in it, and happen to run over a big puddle.. It fried my alternator instantly.
Where did you get your new one from?
So at idle, does it read 12.8?
Do you have a voltimeter so you can test the alternator and battery under the hood?
 
12.8V at idle is about normal. Should see between 12-14. Is your lights dimming when you come down from high rpms to idle? If it is, then your voltage regulator is not working. Its inside the alternator, so you can't just replace it, you have to replace the alternator. If your's is brand new, take it back to the parts store you bought it from and have them test it if its any good. Should have a warranty on it. If comes back good, then how old is your battery/terminals? Also try charging the battery overnight, and trying it then. Battery might not be holding enough charge, causing the alternator to work harder, thus changing your voltage readings. Try these steps, then see what happens next.
 
12.8v is normal?
My battery's normal charge is 12.5..
All the normality i've seen is 14-14.5v.
In addition to above, could also check the belt tension..
 
well this happenend with 2 different alternators and 2 different batteries, both are new. the splash guard on the intercooler is removed (dont think youre talking about this one) and the one on the drivers side has a hole-stripe down the middle of it. (think racing stripe, but its an actual extended, long hole).

yeah at idle (and when the clutch is pushed in while car is still rolling) it would read 12.8ish when it is raining. only seems to be like this for the first 10 minutes of driving maybe. still worries me since this car goes through alternators quickly (just ordered some heatshields just in case).

yes i do have a voltmeter battery. battery seems to be fine.
 
After 3 new alternators and a brand new battery my voltage will be around 13.xx while driving and about 12.5 at idle. Nothing bad is going to happen because of it, so unless it drop's below 12, don't loose sleep over it.
 
what i dont like is the fact that it only happens when it is raining.

the thought of electrical components and water gives me a bad "vibe" :barf: i guess, specially after replacing the alternator every few months!
 
specially after replacing the alternator every few months!
well this happenend with 2 different alternators and 2 different batteries
Let me guess, Advance Auto?

After 3 new alternators and a brand new battery my voltage will be around 13.xx while driving and about 12.5 at idle. Nothing bad is going to happen because of it, so unless it drop's below 12, don't loose sleep over it.
Oh really? Ever been stranded 10 miles from the nearest house in a storm?
12.5v from your alternator is not good. If you think so, wait and see until it goes.
14-15v is normal voltage.
12.5v is normal for your battery.
To maintain a full battery you need at least a 12.5v reading, with nothing running.
Running you need about 14v. Otherwise your draining your battery and you might until it's dead.
It's okay, I learned the hard way too, 4 alternators, 2 batteries.
Go Auto Zone!
 
nope not advanced auto. they are from a shop called Oakcreek Automotive. they are brand new and kinda expensive ($160ish).

yeah 12.5 is not normal at all. thats why i start to worry because if the voltage is in the 12's, that means that its pretty much the battery running.

like i said it only happens when it rains, and the reason why i think that my car is going through so many alternators is because the heatshields are removed. yeah yeah, many cars can run without heatshields and not cause any problems but there are many cases of the alternator not being able to take the heat from the o2 housing and manifold. if you take a look, the o2 sensor housing is RIGHT next to the alternator
 
blackbyrd said:
Let me guess, Advance Auto?


Oh really? Ever been stranded 10 miles from the nearest house in a storm?
12.5v from your alternator is not good. If you think so, wait and see until it goes.
14-15v is normal voltage.
12.5v is normal for your battery.
To maintain a full battery you need at least a 12.5v reading, with nothing running.
Running you need about 14v. Otherwise your draining your battery and you might until it's dead.
It's okay, I learned the hard way too, 4 alternators, 2 batteries.
Go Auto Zone!


Remember your car is 15 years old. It doesn't need the 14.0V-14.5V that today's cars need with all of there electronics. Your car should read 12.5V-12.8V at idle and anywhere from 12.5V-14.0V when driving. That is what the regulator keeps it too. But the biggest part is that the alternator isn't made to put out high voltage because in 1991 it didn't have that much electrical stuff to power. In 2006 there are loads. The Cadillac dealer I used to work for demanded 15.1V out of there alternators at IDLE.
 
Haynes says, any reading under 14v, and the alternator is defective.
My 13yr car puts out 14+volts at idle...
 
Straight out of a 1991 Eclipse Factory Service Manual...
at 68* farenhiet the standard regulated voltage is between 13.9-14.9
 
defiant i have no clue what youre talking about...want to explain a bit more? thanks
 
The harmonic balancer is also known as the crank pulley. It's held on to the cam sprocket by 4 bolts, and drives your alternator and water pump belts. Good catch, Defiant. ;)

A search for "Crank Pulley" or "Harmonic Balancer" should give you lots more information than you ever wanted to know about where it is, what it does, and why you need to replace it.

In the meatime, you can check for play by reaching down there and giving it a good tug. It shouldn't move. If it does, it's most likely slipping. Another fairly common DSM problem.
 
want_a_gsx said:
LOL seems like every other week i learn about a different DSM problem

I guess that's part of what you sign up for when you own a 15+ year old car, eh? ;)

Definitely check out that pulley though - sounds like it could very well be your problem.

No worries if it turns out to be in need of replacement; the crank pulley is surprisingly easy to change (just remove those 4 bolts and give it a few tugs and tap it with a rubber mallet, it'll come off eventually). If you're due for a timing belt job anytime soon, all the better to get it all done at once while you're down there. :)
 
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