Author Topic: Bad alternator? (Read 3438 times)

Travis · « **on:** July 22, 2011, 06:57:33 PM »

So i mixed up the terminals wen jumping the car, yes haha, anyways for awhile the battery light would remain on when the car was off but wasnt when the car was on(which killed my battery over night). Then one day it randomly changed, now the battery light is on when the car is on but not when the car is off. Im pretty sure its the alternator becuase the battery goes dead after like a month. And i do run the car so its not like i let it sit there for a month untouhed. Now everyonce in awhile i have to hook it up to my trickle charger to maintain the battery. So do i need a whole new alternator?

Travis · « **Reply #1 on:** July 22, 2011, 07:14:27 PM »

Oh yea and the light isnt totally bright at idle but wen i rev it it gets brighter then as the revs fall it gets dimmer

92BMW318is · « **Reply #2 on:** July 22, 2011, 07:15:31 PM »

Quote from: Travis;105588

So i mixed up the terminals wen jumping the car, yes haha, anyways for awhile the battery light would remain on when the car was off but wasnt when the car was on(which killed my battery over night). Then one day it randomly changed, now the battery light is on when the car is on but not when the car is off. Im pretty sure its the alternator becuase the battery goes dead after like a month. And i do run the car so its not like i let it sit there for a month untouhed. Now everyonce in awhile i have to hook it up to my trickle charger to maintain the battery. So do i need a whole new alternator?

Did the same thing once, you probably fried your voltage regulator. at pelicanparts.com its like 40 dollars for a new one, depending on the alternator you have.

Autozone sells duralast rebuild "Valeo" alternators. "Valeo" is a german company that also makes parts for BMW's. like 'Bosh', people say bosh is better and Duralast sucks because they do shitty jobs rebuilding parts. but there is a lifetime warrenty on the alternator so long as you own the car.

Just make sure if you get it from autozone you have then bench test it right when you go to get it. This will save you time and troubles when you put it on only to find out it has shitty components in it.

But with all this being said. rebuilt Duralast alternators cost around 140 after core charge. and bosh is some where around 300 and "Valeo" is somewhere around 280.

But only duralast has a life time warranty

Travis · « **Reply #3 on:** July 22, 2011, 07:45:58 PM »

would you trust buying one off of ebay, i see alternators there for pretty cheap, well compared to standered prices at least

DesktopDave · « **Reply #4 on:** July 22, 2011, 10:01:24 PM »

+1 on the voltage regulator. It's easy to put one in and pretty likely fix your problem. It bolts on the back of the alt body by the oil filter housing. The diodes in the regulator are pretty vulnerable to power spikes the wrong direction.

While you're at it, be sure you disconnect the battery. While it's out, get it load tested (and get a second opinion at another store). A bad battery will not provide enough amps to turn the starter after sitting for a while. They're a team, the battery & alternator. I always test them both to be sure.

Pelican lists a Hella regulator for $20.50 and a Bosch for $43. Free shipping over $75...might as well pick up a few more things while you're at it.

If you buy on Ebay, be sure you get the right one off a reputable salvage yard. I'd recommend Vines, I've had good luck with them. Electrical parts from salvage is a risky proposition. Check return policies before you buy!

Travis · « **Reply #5 on:** July 23, 2011, 09:47:40 AM »

Thanks guys! I think ima pop the alt and bat out and have em tested, hopefully its jus the quik fix of the regulator

DesktopDave · « **Reply #6 on:** July 23, 2011, 05:57:48 PM »

Keep us posted.