Running Voltage Too Low, Now Too High

Hi All,

I was wondering if anyone has run into this issue before and could give me some direction.

About a week or so I tested my voltage at the battery terminals of my '82 650 Maxim, and saw that at 2,500 rpm I was only seeing 12.65V, which explained why my battery was draining on rides. Battery is less than a month old, AGM, kept on a battery tender, and does not seem to be bad.

This week I:
- cleaned up the copper ring on my alternator
- removed my stator. Inspected it for any issues with the wiring, and tested the 3 white legs. Between each read between .7 and .8 ohms.

Today I put the battery back in and this time when I tested the voltage at the battery, it was all the way up to 17.69V at 2,500 rpm. I quickly shut it down and pulled the battery again.

When I was experiencing low voltage I thought alternator, now with my current readings, it seems to be the R/R. The fact that I've seen both in the span of 2 weeks makes me think I could be missing something glaring and it is potentially neither.

 

Clean all the connections too. They are not sealed and poor corroded connections can cause under/over voltage situations easily. I've owned/worked on probably 100 bikes in my life and have only ever had an RR bad once, they're pretty reliable and tough components unless shorted or subjected to reverse polarity.

 

Thanks Jayrodoh, looks like I've got some more tests to run.

Concerning that the stator coil resistance should be .46 when I'm seeing .7 to .8 (it is 40 degrees here rather than 68 for what that's worth).

 

28 degrees is not going to make a huge difference in your readings. Assuming your meter is accurate, yes that is not a good reading and could indicate a short somewhere in the stator winding.

 

Test for a voltage difference between your brown wire and red wire (and throughout the harness, so at the RR, in the fuse box, at the battery etc).

Note that the voltage that the RR regulates comes from the Brown wire, and it duty cycles the voltage on the green wire to energize the rotor brushes. This duty cycling regulates the voltage output on the red wire.

Note that the RR does not regulate off of the red wire (to battery), it regulates off of the Brown wire (switched power). If there is a significant drop in voltage in switched power, you're RR would detect a low voltage and keep feeding power to the rotor, over charging the battery. The voltage between the brown and read wires should be very close (within 1V or less).

 

I fired up the bike and it looks like the voltage between the red and brown are very close (red and black = 12.65 brown and black = 12.86) at idle.

At idle the voltage at the battery sits in the high 12's and low 13's. If I give it just a touch of throttle (~1,600 rpm) it reads in the 14V range but quickly jumps into the 15-16 range at any higher rpm.

Attached is my view of the connector

 

rule of thumb. low voltage is an indicator of brushes. you cleaned the rptor rings and noh have high voltage that indicated voltage regulator.

read about charging system in this thread and things to check and clean

The Ultimate Relay, Switch, Sensor, and Diodes Guide

 

Yep I had low voltage before cleaning and now, after cleaning, have high making the brushes seem an unlikely culprit. It's the fact that I've experienced both that makes me question the indication that it would be an issue with the R/R. From what I've read they are pretty much bullet proof, so I've been trying to find any possible issues with the wiring itself.

The connections don't seem to be the cleanest things ever, attached is a picture prior to hitting them with a brush, but don't look to be non-functionally corroded. After taking a brush to connections and making sure nothing had come loose I'm still seeing the same unchecked voltage ramp up. I need to pick up some di-electric grease to hit these points before I'll rule them out.

 

The voltage regulator clamps the voltage and keeps it from going higher than it should. I've had voltage regulators past the diode test using a meter it's still allowed to higher the voltage. Change the regulator voltage back where it belongs.

 

Interesting. I wasn't aware that I could change the regulator voltage.

 

The voltage regulator is that finned aluminum box that goes on the other end of that connector. It is replaceable. the only parts on the bike that aren't replaceable directly other ones manufacturer no longer makes.

 

Go to the website Yamaha parts Nation look up your bike it look up your parts you will see schematics drawings. Voltage regulator would be under electrical 1 or electrical 2. The schematics are great for giving you an idea or insight interparts of the bikes and how they're assembled. I use partzilla myself because you would click on the part number and see what parts cross reference to other bikes

 

The importance of a repair manual. If you look at the pictures posted by, jayrodoh lower left graft chart shows voltage output of the voltage regulator and tells you right underneath it if the voltage levels on proper replace the regulator. Not trying to give you a hard time or anyting just pointing out the importance of Emmanuel

 

I think I'm misunderstanding you. I thought you meant that I could somehow change the voltage at the regulator, which I didn't think could be done. Yeah, I could try swapping out a new regulator and see if that's the fix. It's just odd because from what I've read on here those things are usually the last thing to have problems.

 

They are usually the last thing to fail. Again, if you've tested your harness, and get the same high voltage in the connector between your Red wire to the RR connector and ground, and your Brown wire in the RR connector to ground, then yeah, the RR is definitely suspect. Unless (and this is a bit unlikely), your green wire is somehow getting voltage from somewhere else, like a short. I'm not exactly sure how to test that, except de-pinning it and making sure it doesn't have voltage when it's not connected and the engine is running (you should get zero charging in that situation). But that's just pulling a test out of you-know-where

The RR are super easy to swap out. If there's anyone in Colorado nearby, or has a spare, maybe you can confirm. I've got a couple of spares but I'm in VA.

 

Gotcha. Well I just picked a used one up on eBay for next to nothing so I'll give that a test as well. If it's not the culprit I'll add it to the bonus parts collection. Thanks!

 

This is a good thought but it would be more likely the green wire was shorted to ground. With 12V on the brown wire the regulator pulls the green wire low to sink current through the field coil (rotor), this is the V2 test noted above in the service manual. As the RPM increases the AC Generator output increases so the V2 voltage is adjusted upwards by the regulator to reduce the current through the field coil to maintain the correct voltage output.

With an overcharging condition and checking the V2 voltage if it is at zero with the bike not running or does not rise with the bike running and an increase in RPM then either the voltage regulator is pulling it low or the green wire is shorted to ground, perhaps between the AC generator cover and case.

 

Update: The R/R unit I picked up off eBay came in today and I'm cautiously optimistic; I'm not seeing the spike in voltage that I was experiencing and seem to stay within the 14V range. I do want to verify with a better multi-meter before I put the issue to bed though as I don't think I should trust mine (AstroAI AM33D) and the readings seem slightly higher than they should be.

 

Troublesome Update: Took the bike out for a spin but thought I noticed something funny on the gauges, pulled into a covered parking garage to see in the shade and confirmed that my High Beam light flickers on.

Not sure if there is any particular action causing it to flicker: revving, braking, etc.

Could be from when I swapped out the gauge cluster housing a couple weeks ago, could be from when disconnecting/dropping in the new R/R unit, or maybe it could be that I'm still getting too many volts off the battery?

Will take the meter to the bike again and see if I have any wonky connections in the headlight bucket and back end.

Anyone else ever experience this?