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Posted by: Wyvern Dec 19 2019, 08:29 PM

Can I test my alternator off the car?
I have a choice of 2 units and would like to test.
My local parts store says they cant test it out of the car, only when installed.

Thanks

Posted by: Mark Henry Dec 19 2019, 08:37 PM

Find a rebuilder, here also often called an auto electric shop.
My guy charges $25 but puts it towards a rebuild if needed

Posted by: Tdskip Dec 19 2019, 08:56 PM

+1 on that recommendation

Posted by: cary Dec 20 2019, 08:49 AM

Walked right into NAPA. They have a tester. Take it in back off, no harness.
Took 5 minutes. Old school. Looked to be a new machine.

Posted by: DickSteinkamp Dec 20 2019, 10:09 AM

I have had lots of alternators (internally and externally regulated) tested at my local FLAPS or auto electric shop.

It could be the shop you went to does not have the equipment to spin up the alternator. Find one that does. Most do it for free.

Posted by: bbrock Dec 20 2019, 10:25 AM

Called my FLAPS who assured me they could test an externally regulated alternator. Drove a half hour to town and handed it to them. The hooked it up to their test equipment. NOPE - couldn't test it out of the car. Drove 30 minutes back home with nothing to show for it. I just went through the bench testing procedures outlined in the factory manual with a multimeter. Those test all the components (diodes, windings, etc.) so my assumption is that if all the parts test ok, then it should work. We'll see...

Posted by: bretth Dec 20 2019, 11:14 AM

I wonder if you could secure it in a vice and spin it up with a electric drill off of the pulley nut. Of course you would need to have a load on it and wire in a portion of the charging system somehow.

Posted by: saigon71 Dec 20 2019, 04:26 PM

My local Advance Auto parts was able to test mine out of the car. Do you have an Advanced near you?

Posted by: 76-914 Dec 21 2019, 01:41 PM

You need to have a damn good grip on that drill when you energize the alt.

Posted by: Wyvern Dec 31 2019, 11:43 AM

NONE of the local shops can do this . A Zone, "O" guys, NAPA speed and specialty shop,

Any suggestions as to a known place that can actually do this?
I am in the SF "East Bay" area OR even someone i can send it to?

Heck, for the money I'm tempted to just buy a re-man one and call it done.

Posted by: mepstein Dec 31 2019, 12:05 PM

Our local auto battery shop rebuilds starters and alternators. They test for free. Call your mechanic and ask him where he gets his rebuilt.

Posted by: Spoke Dec 31 2019, 01:00 PM

The RPM's might be an issue. In the vehicle, the alternator spins about 3x as fast as the engine. Thus at 1k RPM, the alternator is spinning at 3k RPM and normally to get the alternator up to 14V one normally needs to increase the engine speed to 1500 to 2k RPM (6k RPM on the alternator).

Most drills do 1k-1.5k RPM. High speed drills might do up to 3k RPM. As you mention, it's the loading that will stress the drill test.

Posted by: Big Len Dec 31 2019, 05:04 PM

Bob's right. Advance will put it on their machine no charge.