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over-voltage from alternator?



 
 
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  #1  
Old January 19th 05, 03:32 PM
Brian
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Default over-voltage from alternator?

What could cause an alternator to put out too high a voltage? I will be
doing some checking tonight, but what has me worried is the wipers are going
too fast when the engine is a road speed but are normal at idle, and the
lights are showing a noticable brightening from idle to say 3000 rpm. Kind
of like an old generator car which couldn't charge at idle.

Probably just worrying on my part, but this is my wife's car which I rarely
drive, and I am always on the lookout for problems creeping up when I do
drive it. 96 Hyundai Elantra, fairly recent battery. Would charge voltage
over 14.5 be a good indication of a problem?

Thanks, Brian

Thanks, Brian


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  #2  
Old January 19th 05, 04:01 PM
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14.5 Volts is fine.

  #3  
Old January 19th 05, 04:16 PM
Spud Demon
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"Brian" > writes in article > dated Wed, 19 Jan 2005 09:32:11 -0500:
>What could cause an alternator to put out too high a voltage?


A bad regulator. I think most regulators are built into the alternators
these days.

>Probably just worrying on my part, but this is my wife's car which I rarely
>drive, and I am always on the lookout for problems creeping up when I do
>drive it. 96 Hyundai Elantra, fairly recent battery. Would charge voltage
>over 14.5 be a good indication of a problem?


If it's 13.5-14.5 it's nothing to worry about. Use a digital voltmeter and
have an assistant rev the engine to normal driving RPMs.

-- spud_demon -at- thundermaker.net
The above may not (yet) represent the opinions of my employer.
  #4  
Old January 19th 05, 04:26 PM
Don Stauffer in Minneapolis
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Spud Demon wrote:
> "Brian" > writes in article > dated Wed, 19 Jan 2005 09:32:11 -0500:
>
>>What could cause an alternator to put out too high a voltage?

>
>
> A bad regulator. I think most regulators are built into the alternators
> these days.
>
>
>>Probably just worrying on my part, but this is my wife's car which I rarely
>>drive, and I am always on the lookout for problems creeping up when I do
>>drive it. 96 Hyundai Elantra, fairly recent battery. Would charge voltage
>>over 14.5 be a good indication of a problem?

>
>
> If it's 13.5-14.5 it's nothing to worry about. Use a digital voltmeter and
> have an assistant rev the engine to normal driving RPMs.
>
> -- spud_demon -at- thundermaker.net
> The above may not (yet) represent the opinions of my employer.



If it goes above 15 volts, however, you should get it fixed. Nothing
will kill a battery faster than too high of a charge voltage. BTW, most
voltage regulators have a temp dependent circuit. They will charge
higher voltage in cold weather. A good manual should have a spec on
voltage vs temp. In meantime, if it is a battery you can check fluid
level, do so very frequently. Overcharging kills battery by boiling out
electrolyte.

If you do not have a voltmeter in car, you can buy nice ones that plug
into cigarette lighter.
  #5  
Old January 19th 05, 04:44 PM
TCS
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On Wed, 19 Jan 2005 15:16:46 +0000 (UTC), Spud Demon > wrote:
>"Brian" > writes in article > dated Wed, 19 Jan 2005 09:32:11 -0500:
>>What could cause an alternator to put out too high a voltage?


>A bad regulator. I think most regulators are built into the alternators
>these days.


If it's a bad regulator, the alternator can be taken to an autoelectric repair
shop and repaired for a lot less than a replacement alternator, typically
$50-90. If you can't find one in the yellow pages it's because rents in your
city are too high and smaller business can't stay in business.
  #6  
Old January 19th 05, 05:16 PM
Mike Romain
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Whenever my alternator acts like that, I either have a loose or polished
up fan belt or a dirty main battery connection.

With the bad belt, the battery is never fully charged so the alternator
is trying to 'catch up' so I see a high reading on the volt gauge and
the lights get brighter.

When I have a bad connection, same deal except it seems to put out
higher to jump the bad connection.

Or the alternator's regulator could just be worn out.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Brian wrote:
>
> What could cause an alternator to put out too high a voltage? I will be
> doing some checking tonight, but what has me worried is the wipers are going
> too fast when the engine is a road speed but are normal at idle, and the
> lights are showing a noticable brightening from idle to say 3000 rpm. Kind
> of like an old generator car which couldn't charge at idle.
>
> Probably just worrying on my part, but this is my wife's car which I rarely
> drive, and I am always on the lookout for problems creeping up when I do
> drive it. 96 Hyundai Elantra, fairly recent battery. Would charge voltage
> over 14.5 be a good indication of a problem?
>
> Thanks, Brian
>
> Thanks, Brian

  #7  
Old January 19th 05, 05:41 PM
Bruce Chang
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"TCS" > wrote in message
...
> On Wed, 19 Jan 2005 15:16:46 +0000 (UTC), Spud Demon
> > wrote:
>>"Brian" > writes in article
> dated Wed, 19 Jan 2005
>>09:32:11 -0500:
>>>What could cause an alternator to put out too high a voltage?

>
>>A bad regulator. I think most regulators are built into the alternators
>>these days.

>
> If it's a bad regulator, the alternator can be taken to an autoelectric
> repair
> shop and repaired for a lot less than a replacement alternator, typically
> $50-90. If you can't find one in the yellow pages it's because rents in
> your
> city are too high and smaller business can't stay in business.


Very good advice. I recommend getting a electric shop to fix your
alternator as well. The good thing is they will fix what's wrong, not just
replace everything and hope that they get it. They have the ability to
diagnose and repair the alternator properly. Around here (Dallas, Texas)
the local shop will fix any alternator for $45, replacing only what's gone
bad. Also, the shop uses better components than those that are found in the
rebuilt units of the auto stores.

-Bruce


  #8  
Old January 19th 05, 06:16 PM
Daniel J. Stern
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On Wed, 19 Jan 2005, Bruce Chang wrote:

> > If it's a bad regulator, the alternator can be taken to an
> > autoelectric repair shop and repaired for a lot less than a
> > replacement alternator, typically $50-90. If you can't find one in
> > the yellow pages it's because rents in your city are too high and
> > smaller business can't stay in business.


> Very good advice. I recommend getting a electric shop to fix your
> alternator as well. The good thing is they will fix what's wrong, not just
> replace everything and hope that they get it. They have the ability to
> diagnose and repair the alternator properly.


They also have the ability to swear and curse at their would-be customers
who bought Korean cars and are dumb/ignorant enough to expect to be able
to fix them.
  #9  
Old January 19th 05, 06:46 PM
Steve
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Brian wrote:

> What could cause an alternator to put out too high a voltage?


Several things pop to mind.

-Failed voltage regulator
-Short to ground in the field circuit (if its a
regulate-on-the-ground-side design like most are)
- short to ground in the alternator rotor itself.
- broken wire to voltage regulator reference



  #10  
Old January 19th 05, 07:21 PM
TCS
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On Wed, 19 Jan 2005 12:16:08 -0500, Daniel J. Stern > wrote:
>On Wed, 19 Jan 2005, Bruce Chang wrote:


>> > If it's a bad regulator, the alternator can be taken to an
>> > autoelectric repair shop and repaired for a lot less than a
>> > replacement alternator, typically $50-90. If you can't find one in
>> > the yellow pages it's because rents in your city are too high and
>> > smaller business can't stay in business.


>> Very good advice. I recommend getting a electric shop to fix your
>> alternator as well. The good thing is they will fix what's wrong, not just
>> replace everything and hope that they get it. They have the ability to
>> diagnose and repair the alternator properly.


>They also have the ability to swear and curse at their would-be customers
>who bought Korean cars and are dumb/ignorant enough to expect to be able
>to fix them.


Newsflash: there are no 100% domestic cars or 100% japanese cars.
Your statement was nonsensical.
 




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