I asked this question a couple of years ago and thought I would ask again. I have a few spare alt's and wondered how to bench test them. I know how to check them in the car but how are ours bench tested? I have gone into some flaps but they don't know how. Just said that ours won't work on their tester??

Short answer: You cant.

Long answer:
If you setup a special bench you can.
The alternator would need a voltage regulator plugged into the alternator harness (connector is the same as on the relay board)
Then a 12V source (battery) would need to be connected to the D+ of the voltage regulator (red wire) with a 2-3W bulb in series.
Ground the battery to the alternator chassis.

Then fire away.
Light should be ON before cranking the alternator.
Once the alternator gets up to speed, the light should go out.

Then apply the test load and monitor voltage.

Stu

Autozone tests for free.

BTDT they cant test our alts.

I took mine to NAPA Auto. At first he said he couldn't then tried anyway. He made 3 runs. First two passed. The third failed. I am glad he kept trying. It was the voltage regulator connection that had him confused.

Bad diodes to the regulator?

I have set up a mock test where I drive the alt from a drill and hook up leads. You can feel the load when it makes power. But then, I don't know how much I know from that. I found out it can make more than 12 volts, but not whether it does in a real load.

I know you live out in the "boonies" but you say there isn't an automotive electric shop that can't check out that alternator? If the alternator is making 14 volts or slightly less, then what's the problem. (Keeping in mind I know less about electricity than most people and consider it to be a technical kind of VOODOO).

OK gramps, put on your glasses and go back read the first post. I said "extra alt's". I know you have lots of energy so come on down and swap these out for me while I start the car and check the voltage, one by one.

That is what I thought. I used a different alternator.

OK you Texas shit kicker, go back and read the first sentence of my post.

Flattery will get you everywhere. I'll have to reread this tomorrow so I can figure out what you mean. Then again I just came in from an all nightter and can't even spell my own name right now.

ILBT