Alternator problems

jigthumper

Joined
May 4, 2007
Messages
13
Location
neenah,wi
Bike
94 st1100
My 94 with 28 amper, and 41000 miles started acting up today. Voltage dropped from normal 14.7 volts to 12.5, then slowly to 11.8 by the time I made it home. all connections were routinely cleaned and greased. No signs of heat or trouble at vrr or connections. The battery shows 12.5 volts yet with bike off, but drops tp 11.8 at start up. Is there a simple way to test the vrr? Does someone whose done an upgrade have one to sell if I need one? I have a multimeter but only use it for voltage testing. Any hints or help would be appreciated. Thanks, Bob
 
Bob, sounds like a bit of a problem there. Could be a bad VRR or a dying battery.

How old is the battery? Do you have another one that you can swap out to test? Most any 12V battery will work for testing purposes. A garden tractor battery will do. Swap the battery, start the bike and check the output.

It may also be that you have a winding that has gone open. If you pull the connector from the VRR and check each of the 3 yellow (I think) wires you should show 6-8 ohms resistance.

Set the meter to OHMs at it's lowest range (upside down U), put the black lead on the - terminal of the battery and use the red lead to connect to each of the 3 yellow wires (one at a time) from the alternator. The 3 readings should be about the same. If you get one reading that doesn't change (open) or has even less resistance (short) it's time to replace the alternator.

If the alternator tests OK, then you will want to change the VRR.

Good Luck and keep us posted!
 
sirepair said:
.... It may also be that you have a winding that has gone open. If you pull the connector from the VRR and check each of the 3 yellow (I think) wires you should show 6-8 ohms resistance.

Set the meter to OHMs at it's lowest range (upside down U), put the black lead on the - terminal of the battery and use the red lead to connect to each of the 3 yellow wires (one at a time) from the alternator. The 3 readings should be about the same. If you get one reading that doesn't change (open) or has even less resistance (short) it's time to replace the alternator....
Click to expand...


Where'd you get this test/check/info, Pat? Have you actually used it? Doesn't look like the "Alternator Inspection" stator windings continuity check from the Honda Service Manual that I just sent to Bob after he emailed me. I'd poST my scan of the manual page (p. 17-6) here but the mods will delete it. Continuity of a stator yellow lead-to-ground shows a failed winding.

I also sent Bob the stator A/C output check that Dan Alameda poSTed here recently.

Regards, John
 
Thanks, gotta leave for work now, will check tomorrow. Battery is 3 years old. Bike starts and runs fine. I'd have no clue that something was wrong if not for the volt meter. Can this be a battery problem if the bike starts fine? Also, voltage remains constant with revving. thanks
 
jigthumper said:
Is there a simple way to test the vrr? Does someone whose done an upgrade have one to sell if I need one? I have a multimeter but only use it for voltage testing. Any hints or help would be appreciated. Thanks, Bob
Click to expand...

Unfortunately you cannot reliably test the VRR with a multimeter unless it is the exact model meter specified in the Honda service manual. Any other multimeter returns nonsense readings, BTDT. The simplest thing to do is replace it with a known good one to see if that corrects the charging issue.

I think you can deduce a bad VRR if all of the stator tests John O sent you show it to be in good shape. Historically however, it seems the stator is more often the culprit. Time for an upgrade me thinks.
 
The Battery sounds like its doing a good job. The alternator if its working will keep the system voltage at about 14V. The way the voltage is dropping as you describe, then it looks like a charging problem.

It may be a dropped diode in the the reg/rectifier pack, or a buggerd alternator itself...
 
jigthumper said:
Thanks, gotta leave for work now, will check tomorrow. Battery is 3 years old. Bike starts and runs fine. I'd have no clue that something was wrong if not for the volt meter. Can this be a battery problem if the bike starts fine? Also, voltage remains constant with revving. thanks
Click to expand...

Hi, the voltmeter you are talking about attached to bike. On a recent trip, my volt too started to drop. It would start out in 14 v, then slowly start to drop, 11 to 10 and then down as low as 9,8 volts, I thought my alternator was going or the vrr. I checked everything, it all looked good. I worried about it the whole trip, until I put a piece of tape over meter for the rest of the trip. Everything was fine, the bike ran great for the rest of the trip. When I returned, took everything apart and found the ground wire for the voltmeter was loose...tighten it up amd it has been fine every since. Don't forget about the simple things when checking for a problem!! I would have bet any money that my alternator was going. Good Luck!!
 
Checked AC voltage between all yellow terminals on red 3pin from alternator. Showed constant 1.7 at idle and 2.1 at 2500 rpm. Not looking good. Will try to aquire a loaner vrr to check before ordering parts. Also, did check voltage with a multimeter ind not just trust the bikes meter. Thanks for the help. Bob
 
Avtrician said:
The Battery sounds like its doing a good job. The alternator if its working will keep the system voltage at about 14V. The way the voltage is dropping as you describe, then it looks like a charging problem.

It may be a dropped diode in the the reg/rectifier pack, or a buggerd alternator itself...
Click to expand...

This might be true for the 40A unit which has an integral VRR but there are no diodes in the 28A stator, all the rectification and regulation action for the 28A are handled by the separate VRR.
 
Static checks on yellow 3 prong (all.9) black to white 3.6, and no continuity between any terminal and ground. so all seem ok. If I knew anybody local(but I don't) I could put my vrr in theirs to test, without putting a known good one in mine and possibly frying it if the stator is bad. So static checks good, and recommended running check suspect. Now what?
 
I hope you find an inexpensive solution . . . . if that's what you really want, but with 41K on a 28 amp unit I wouldn't spend a dime trying to fix it . . . . if you intend to keep and ride the bike, or if you ever plan on taking it very far from home

It's given you fair warning and close to home at that - If you're gonna keep it and ride it, now's the time for the 40 amp upgrade . . . . you know what's going to happen if you don't . . . . you just don't know WHERE

Don
 
You're right, a vrr has me going for now but a 40 amper is in my future. But not in the middle of summer.
 
good luck thay are a pain to repalce im still working on mine got the alternator in now the nike does not run *****
 
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