# Multiple alternator failures
**URL:** https://boards.straightdope.com/t/multiple-alternator-failures/171846
**Category:** Factual Questions
**Created:** [April 29, 2003, 3:48am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846 "2003-04-29T03:48:54Z")
**Posts on this page:** 16
**Page:** 1
### Author:  [@billy](https://boards.straightdope.com/u/billy)
#### Post date: [April 29, 2003, 3:48am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/1 "2003-04-29T03:48:54Z")
My wife has a 1988 Honda Prelude. About 3 months ago, the alternator failed. I replaced it with a rebuild that had a lifetime warrentee. I checked the system voltage after install and it was fine but the new one failed within two days.
I took it back to get it replaced with a new one and they put it on the tester and verified it was dead.
The second new one died today.
Am I having real bad luck or is something in the car killing the alternators? The battery is new, the car runs fine when the alternator is working with the system at about 14.5V. All the fuses are in place and intact.
It doesn’t cost me anything to replace it and takes only about 40 minutes but damn, 3 failed alternators in 3 months.
What is going on? Any help is appreciated.
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### Author:  [@FranticMad](https://boards.straightdope.com/u/FranticMad)
#### Post date: [April 29, 2003, 4:03am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/2 "2003-04-29T04:03:07Z")
Are you sure that it isn’t just a 4-year old battery that needs to be replaced? You could be getting scammed by the garage (I know this is a shocking idea).
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### Author:  [@Princhester](https://boards.straightdope.com/u/Princhester)
#### Post date: [April 29, 2003, 4:05am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/3 "2003-04-29T04:05:23Z")
He’s already said the battery’s new, FranticMad.
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### Author:  [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)
#### Post date: [April 29, 2003, 4:05am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/4 "2003-04-29T04:05:55Z")
How could the garage be scamming him? He only paid for the first rebuild, all the replacements are free, under the lifetime warranty. They’d just be losing money at this point.
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### Author:  [@billy](https://boards.straightdope.com/u/billy)
#### Post date: [April 29, 2003, 4:06am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/5 "2003-04-29T04:06:35Z")
> [@](#):
>
> \*Originally posted by FranticMad \*
> \*\*Are you sure that it isn’t just a 4-year old battery that needs to be replaced? You could be getting scammed by the garage (I know this is a shocking idea). \*\*
I heven’t been to a garage. I am testing and replacing them myself. IN addition to that, they test them at the shop when I return them to verify they are really dead before giving me a new free one.
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### Author:  [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)
#### Post date: [April 29, 2003, 4:43am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/6 "2003-04-29T04:43:44Z")
I’m surprised by now the alternator shop hasn’t demanded to see billy’s car in their shop so they test the rest of the charging system and cut their losses on those free rebuilds.
What is the failure? Are the diodes getting fried, or does this one have an internal voltage regulator? Speaking of which, have you tested the regulator, assuming it’s external to the alternator?
I’m also wondering about a shorted cell in the battery? A new battery would have enough spare “oomph” to hide such a fault.
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### Author:  [@billy](https://boards.straightdope.com/u/billy)
#### Post date: [April 29, 2003, 4:52am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/7 "2003-04-29T04:52:39Z")
The battery was replaced shortly after the second alternator failed to gaurd against just such a problem.
The regulator is in the housing.
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### Author:  [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)
#### Post date: [April 29, 2003, 4:55am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/8 "2003-04-29T04:55:30Z")
> [@](#):
>
> \*Originally posted by gotpasswords \*
> \*\*I’m also wondering about a shorted cell in the battery? A new battery would have enough spare “oomph” to hide such a fault. \*\*
Each of the 6 cells in a lead acid battery has a nominal 2-volt output. I’d think a 10-volt open-circuit reading would would be pretty indicative of a shorted cell.
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### Author:  [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)
#### Post date: [April 29, 2003, 5:03am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/9 "2003-04-29T05:03:55Z")
It sounds like you have an intermittent short in the car’s electrical system. I had a Lincoln Continental which was doing something similar, the problem, according to the shop I took the car to, was related a wire under the dash. Let someone who’s familiar with the electrical system in that model car take a look at it.
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### Author:  [@MajorTom](https://boards.straightdope.com/u/MajorTom)
#### Post date: [April 29, 2003, 5:28am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/10 "2003-04-29T05:28:57Z")
Kinda depends on who is the rebuilder. We got a place out west called the Burnside Bridge. A place called Wi **ame** e Electric hires people who live under that bridge to "rebuild alternators, starters and the like. Wi **ame** e (missing a couple LL’s and TT’s) is a river flowing into the Columbia. I’ve experienced repetitive failures on rebuilt parts from other rebuilders also. Used to be a 2 year warranty meant that when it failed prematurely, the new warranty began a new warranty period. Not anymore. Lifetime means what? Yours, mine, the alternator’s, or the car’s? You get what you pay for. (an example would be my free advice to bite the bullet and go to Honda and have them do the job) Not cheap, but the problem will be solved.
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### Author:  [@Gary\_T](https://boards.straightdope.com/u/Gary_T)
#### Post date: [April 29, 2003, 12:23pm UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/11 "2003-04-29T12:23:09Z")
While it’s not out of the question that there’s some problem external to the alternator that is overstressing them and causing the failure, by far the most likely cause is poor quality rebuilds. The guarantee is strictly a financial agreement–it does not have any effect on the physical properties of the alternators.
I know of one case where 6 replacement alternators failed. The final solution was to get an alternator from a different source. If you experience another failure, I would advise you to do likewise.
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### Author:  [@Gary\_T](https://boards.straightdope.com/u/Gary_T)
#### Post date: [April 29, 2003, 12:32pm UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/12 "2003-04-29T12:32:22Z")
> [@](#):
>
> \*Originally posted by MajorTom \*
> **Used to be a 2 year warranty meant that when it failed prematurely, the new warranty began a new warranty period.**
While some vendors may have operated that way, that’s not what a 2 year warranty means. The warranty doesn’t guarantee that the device will last for two years–it guarantees that the purchaser won’t pay a second time for the product (or service) during the 2 years. The two years starts at the time of initial purchase, and ends 2 years later regardless of whether or not product replacement has been made under warranty in the meantime.
> [@](#):
>
> \*\* Lifetime means what? Yours, mine, the alternator’s, or the car’s? \*\*
Usually it’s written as the original purchaser and the original vehicle.
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### Author:  [@stevephillips](https://boards.straightdope.com/u/stevephillips)
#### Post date: [April 29, 2003, 2:23pm UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/13 "2003-04-29T14:23:54Z")
The quality of rebuilt alternators (and starters) varies greatly depending on where you buy them. A couple years ago when a friend from out of town was visiting us, his alternator went out and I helped him replace it. He bought one at a well known auto parts chain store and we put it in. It was bad. We took it back. The store tested it. Yup, it’s bad. So before we took another home, we insisted they test it. It was bad too. They went through two more before they found one that worked.
I’ve had good luck with rebuilt alternators and starters from NAPA, but not from other stores.
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### Author:  [@billy](https://boards.straightdope.com/u/billy)
#### Post date: [April 29, 2003, 7:31pm UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/14 "2003-04-29T19:31:12Z")
> [@](#):
>
> \*Originally posted by MajorTom \*
> \*\*We got a place out west called the Burnside Bridge. \*\*
I used to skateboard under that bridge.
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### Author:  [@billy](https://boards.straightdope.com/u/billy)
#### Post date: [April 29, 2003, 8:01pm UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/15 "2003-04-29T20:01:03Z")
> [@](#):
>
> \*Originally posted by Tuckerfan \*
> \*\*It sounds like you have an intermittent short in the car’s electrical system. \*\*
I had considered that but none of fuses are blown and the car runs fine. If it was a short in a unfused wired, the car should die or at least smoke. If fused, the fuse should open.
The field coil voltage suuply is fused at only 10Amps so a short in the field coil would cause the fuse to open.
I’m just gonna go get another one and try my luck again. I got the thing out of the car this morning in 8 minutes. Install should be only slightly longer.
Switching to a high quality part will cost much money, and sticking with the cheap ones, I will likely end up with one that is good eventually.
Thanks for all the advice.
Let’s shut this thread down.
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### Author:  [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)
#### Post date: [April 30, 2003, 4:06am UTC](https://boards.straightdope.com/t/multiple-alternator-failures/171846/16 "2003-04-30T04:06:55Z")
> [@](#):
>
> \*Originally posted by billy \*
> **I had considered that but none of fuses are blown and the car runs fine. If it was a short in a unfused wired, the car should die or at least smoke. If fused, the fuse should open.**
Perhaps, but the Lincoln that I owned which was eating alternators never did any of that. It’d just blow the alternator.