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Alternator or Voltage Regulator. Which one's going?


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Over the past few days, the battery has not been charging. With a battery charger I was able to get enough juice in there to start the engine. When driving, the voltage indicator on the dash is moving erratically between 11 and 13 volts (approx). I checked the two connections on the alternator, but problem persists.

Should I replace the alternator or the voltage regulator?

Joost

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Hi Joost,

it seems to be the voltage regulator.

If the battery can be loaded via external loader, it should be OK.

Voltage regulator is a small budget part (aprox. 30$) i would give this a try first (alternator= 500$).

My first post here is a DIY for this issue, i had the same probs a few weeks ago.

CU

André

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No, it´s not integrated, but mounted outside with exaxt 3 Philips-screws.

Dismounting takes 2 minutes.

You can of course change the complete alternator, it´s just a question of costs :-)

Regards

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I bought a remanufactured duralast alternator from autozone.com for $300 with shipping with $105 core return. So it ended up costing under $200.

When I took the core back to Autozone, they refunded me the whole $300 in error..... :)

So it was a free alternator for me

Kristian

Oh, I see. I guess it's not worth $500 if ti's that easy to replace. But it is just a matter of time for the alternator as well. Mine croaked @ 85k.
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Hi Joost,

it seems to be the voltage regulator.

If the battery can be loaded via external loader, it should be OK.

Voltage regulator is a small budget part (aprox. 30$) i would give this a try first (alternator= 500$).

My first post here is a DIY for this issue, i had the same probs a few weeks ago.

CU

André

Can someone point me to the diy voltage regulator replacement post? I searched but can't find it.

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  • 2 weeks later...

A quick update:

- Had the alternator tested at Autozone. Their machine tests the alternator AND the voltage regulator. Both passed.

- Had the battery tested and all within spec.

- Even with the battery fully charged the starter does not "run". Just a clicking sound upon ignition. So far I did not inspect the starter, because it is a less than a year old reman.

Nonetheless I decided to replace both the battery and alternator (reman from Autozone for the latter). Just to be on the safe side. In the process got a lot of tips from the people at Autozone, Advance etc.

Other checks done so far:

- Voltage WITH battery connectors attached: varies between 11.9 and 13.9 V DC.

- At some point the engine died when disconnecting the battery poles. When doing that for a second time the engine almost died, but caught itself and went back to stationary.

- At some point I have also measured an AC voltage around 24-25V (with the battery poles dissconnected), indicating a bad voltage regulator, I guess. The **** thing is new though!

I am starting to think that the small wire feeding off the main harness on the engine to the alternator may be the culprit. I assume this is the wire that provides a current to either the stator or rotor of the alternator and somehow this little guy is wreaking havoc, and hence the temperamental behavior of my alternator. Is there a way to check this with the engine running?

Another theory of mine is that the starter motor is stuck and is drawing a current because it is not properly disengaging, thus causing the strong differences in charging voltage.

As you can imagine, I am getting a little frustrated and your comments are more than welcome.

Joost

Edited by jperquin
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Joost

It's a very bad idea removing the battery poles (or the battery) with the engine running, the operative power peaks can destroy the alternator or diode bridges.

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Joost

It's a very bad idea removing the battery poles (or the battery) with the engine running, the operative power peaks can destroy the alternator or diode bridges.

Thanks for the warning. Should I start from zero again and have the alternator bench checked again?

Do any of my concerns above make any sense to you?

Joost

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Check the V on the alternator output engine idling (in DC never in AC) - check the V on the battery engine idling - what's the difference, if there is any bigger than approx. 0.4 V - check the grounds - check the V drop while activating the starter (may not be less than approx. 11.5V for good response)

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After having spent over 400 bucks on a new alternator and battery, it turns out the connection from the engine to the battery positive was loose.....

There is a little door right above the AC pump with a big + on it. When we dropped the engine over X-mas, I assume this little nut was not tightened properly and came loose on the track a few weeks ago.

On the positive side, I reconditioned the starter and have a new (much "whinier") alternator. and don't have to worry about the battery for the years to come either.

Thanks to all for your suggestions and comments and special kudo's to RFM. "Hartelijke dank" to my fellow Dutch speaking renntech-er.

Joost

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