How to test an alternator off bike?

[HayHauler]

I have a couple of alternators that I need to test to see if they charge.  I DON'T want to install them just to see if they work. One of them i know is good,  because the reason for replacement was that the nut came loose, not that it quit charging.  But,  I can't remember which one it is!

I have them on a bench attached to a12v battery. The grey plug i have on an alligator clip.  I have a ground wire from the negative pole on the battery to the case of the alternator. 

I have spun the alternator in both directions and gotten no change in monitored voltage. I have also tried attaching the plug (grey covered wire)  on both the negative and positive posts with no change in voltage.

Do any of you know what I am doing wrong?   
Open for suggestions.  I have looked at the wiring diagram and couldn't determine the err of my ways. 

Someone HAS to have done this in the past. 

New Goldwing alternators are $560 from Ron Ayers. 

Hay 
Jimmyt

[HayHauler]

P.S.  The positive post is fused to prevent any damage to the unit.
Yes, the fuse tests good. 

Hay 
Jimmyt

[Pluggy]

Have an AutoZone close by?  Those stores have a test machine that gives a real test under load.  If that alternator fits the machine it would be a good test.

Now if you want to continue the self test, remember that Valkyrie doesn't start generating until around 900 rpm. You can't expect much generating just twirling it with your fingers.

[HayHauler]

Have an AutoZone close by?  Those stores have a test machine that gives a real test under load.  If that alternator fits the machine it would be a good test.

Now if you want to continue the self test, remember that Valkyrie doesn't start generating until around 900 rpm. You can't expect much generating just twirling it with your fingers.

https://1drv.ms/i/c/b96b326dcefe9b4d/EVbKamEZ6l1Lkvh0PWjEbOgBiWlwtud7A5K2SutcoOim3w?e=DAIzNw

I was using my drill motor with a rubber awl to spin the alternator that is clamped in the WorkMate by the 2 ears for bolts.  I got it up to about 1200 rpm, but still no joy.  I tried applying 12v to the grey wire that connects under the seat, but still nothing.
AutoZone couldn't test it because they "didn't have a matching harness".  Evidently, they can only test car/truck alternators.  Chevy, Dodge, Ford, Toyota, Nissan, no problem.

Hay 
Jimmyt

[Pluggy]

Anything connected to the output post?  Try hooking up a headlight bulb between that post and the alternator case, then run it.

[HayHauler]

Anything connected to the output post?  Try hooking up a headlight bulb between that post and the alternator case, then run it.

I connected the positive post of the battery to that "output post" on the alternator.  I connected my VOM to the battery via pigtails.  Should I connect a headlight (applying a load) to the connections as well?  That might provide the load to energize the alternator to start charging.
Thanks for that.  I will attempt this evening and report back.

Hay 
Jimmyt

[Pluggy]

First question..... Do you have the little cable with the white connector?  It plugs into the back of the alternator.

[HayHauler]

First question..... Do you have the little cable with the white connector?  It plugs into the back of the alternator.

Yes.  I applied 12v to it in hopes to energize the "field", but it didn't change the output.


Hay 
Jimmyt

[Pluggy]

This is what I would try.  I haven't had the time to remove the alternator from my bike and try it myself.

Battery plus connects to the black and green wire on the "control cable".  This is can be done at the white connector.  Battery minus goes to case of the alternator.  Headlight-type bulb gets one wire to alternator output post and the other wire to the alternator case.  Make sure you have good clean connections.

Spin it fast while measuring voltage across the headlight bulb, even if the bulb doesn't light up..

What little I read suggests that a load is required for the alternator generate.  That 55 watt headlight bulb should be enough load to make that happen.  If not, we can try something else.

[HayHauler]

Anything connected to the output post?  Try hooking up a headlight bulb between that post and the alternator case, then run it.

I connected the positive post of the battery to that "output post" on the alternator.  I connected my VOM to the battery via pigtails.  Should I connect a headlight (applying a load) to the connections as well?  That might provide the load to energize the alternator to start charging.
Thanks for that.  I will attempt this evening and report back.

Hay 
Jimmyt

This is connected to the large post on the back of the alternator.  If you look at the pic I posted, you can barely see the large red line, with the fuse, going behind the alternator and contacting the large post on the top right side of the alternator.

Should this large cable not be connected to the large post on the back?

Hay 
Jimmyt

[Pluggy]

Let's see if this will work:

Disconnect everything. 

Put two leads on a headlight bulb and test it with your battery. 

Connect one of headlight bulb leads to the output post that looks like a bolt.  Also connect the plus lead from the multimeter to this same output post.

Connect the other lead from the bulb to the case of the alternator. 

Connect the plus side of the battery to the green and black wire terminal inside the white connector. 

Connect battery minus to the alternator case. 

Connect the minus lead of the multimeter to the alternator case.

Turn on multimeter and spin the alternator, at increasing speed.

Read voltage.

[HayHauler]

Let's see if this will work:

Disconnect everything. 

Put two leads on a headlight bulb and test it with your battery. 

Connect one of headlight bulb leads to the output post that looks like a bolt.  Also connect the plus lead from the multimeter to this same output post.

Connect the other lead from the bulb to the case of the alternator. 

Connect the plus side of the battery to the green and black wire terminal inside the white connector. 

Connect battery minus to the alternator case. 

Connect the minus lead of the multimeter to the alternator case.

Turn on multimeter and spin the alternator, at increasing speed.

Read voltage.

Thanks again Pluggy!!  I will try this and report back my findings.

Hay 
Jimmyt