Shadow charging questions...

[reddman2369]

Hey all you Tech Heads!

I am digging into a charging issue on my 2001 VT1100C. This process started when I discovered voltage dropping when I raised RPM after a new battery install. I have done all the normal stuff. The battery is fully charged. Checked grounds, wiring continuity, etc.
The stator connector was getting hot and I replaced it. Stator resistance is normal on all 3 windings. No internal shorts to ground on any windings. Voltage regulator wiring continuity is good.

I unplugged the stator while the bike was running and there was an unmistakable increase in RPM when I unplugged the stator. Voltage at the battery stayed dropped to 12.5VDC, which I expected. I got approx. 40VAC with the stator unplugged from all 3 windings. I locked the throttle while I ran lamp tests (to compare winding brightness) and tested each winding with a 60 watt 120VAC light bulb. I get about the same brightness from each winding and all windings will increase the lamp output with an increase in RPM.

This is what I'm now seeing, Voltage regulator output is 14.2 VDC at idle, 13.8 VDC at roughly 5,000 RPM and the voltage will go no higher at any RPM. I don't have a tach, so the RPM is a very rough estimate.

I may be chasing phantoms but I am not sure how to interpret the RPM increase when the stator was unplugged.

Is this normal behaviour? Is the voltage regulator abnormally loading the stator output? Should the no-load AC output of the stator be higher?

Anybody had experience with this? Feel free to increase my education. Thanks...

[verdeva]

Did you measure the stator voltage line to line, or line to ground? Correct is line to line.

[John Hopkins]

Voltage from your stator is a/c..yours is probably fine.. measuring from stator to frame will not give you a true reading, but it sounds as if you have plenty..from there the voltage goes to the rectifier this does what it says on the packet and rectifies the voltage from a/c to d/c..now at this point if that was all there was, and the rectifier was working correctly as you increase the revs you would continue to increase the d/c voltage until it got so high that things started to blow..so you have a voltage regulator..which is a solid state package of components that stop the voltage from exceeding a preset voltage...in this case up to 14.8vdc depending on the set up...

so assuming you measured correctly and the stator is ok, you should have a faulty reg/rec..

I don't have the same bike as you so hang on before you rush out to the parts store and see what someone with your bike says about it.. It is also possible that a loose wire anywhere in the setup I described could be losing voltage when you increase speed due to vibration and this could give a similar result..

A volt or ohm reading from the negative terminal of the battery to the frame (when you lose the voltage) would be a good idea..both volts and ohms should read zero as the two points should be tied together.

John.

[Earthling789]

It would appear from your post that the stator is behaving normally, but the problem is in your rectifier. As you increase RPM, the output voltage should move UP, not down or become wishy-washy....

While the Rectifier may pass the diode test, it still may be failing under load / heat from the regulator side of things... this would explain the decrease in output from 14.2V to 13.8V when increasing the RPM from idle to 5000.

IMO, 14.2V is high for idle output, but I'm not familiar with the charging system of your particular bike.... it may be "normal"... but you'd have to check a shop manual for your year/model to be sure of what the idle and 5000-RPM outputs should be. Either way... it should go UP, not down as you increase RPM.

If you can, borrow a rectifier from a friend, or at least test their bike's DC-V output at idle and 5000-RPM to determine if yours is working the same or faulty before shelling out for a new one... my guess, though... yours is faulty.

[jpr1968]

13.8 volts should be enough to charge your battery. To check your stator the best way is to check ac out between each set of wires at higher rpm. Should be about 70ac at 5,000rpm.

[PainterD]

This us pretty much the same issue I had with mine. I always thought it was the stator, after reading so many members had to change theirs. But once I found a better regulator, I found that to be the answer I was looking for.
The stock regulators are not very good (along with cheap wiring which is too thin) and run very hot, which will eventually take out your stator.
After searching the net for a better voltage regulator, I found a site that I was looking for. I was pleasingly surprised to see the results on my volt gauge once I installed my new regulator.

Here's the article that I found that explains it:


http://roadstercycle.com/Shindengen%...rade%20kit.htm

[oconeedan]

I am thinking you have nothing wrong, unless I am reading something wrong.
So your RR puts out 14.2v at idle and 13.8 at high rpm....that's fine. Your RR is working, it is keeping the voltage over 13.5 which is what you want.
Your voltage from the stator is ac, and it is choppy at lower rpms, which may be the reason for the higher voltage from the RR at idle. I still say no big deal as long as it's over 13.5vdc.
When you unplug your stator, your bike rpm jumps because you have taken a big electromagnet off of your engine. Your stator acts like an electromagnet when it is connected, this is how voltage is made. Disconnect it, and you reduce the drag on your engine.
From what I read, everything is OK.
Someone please correct me if I am wrong.
Dan

[reddman2369]

Thanks Folks very much for the replies.

Dave, Stator voltage was tested line to line. Resistance was tested line to ground.

John, I did have some voltage drop in the ground path. Cleaned stator and regulator wiring grounds which was part of my original test results.

Earthling789, At this point I believe the regulator has a problem and is failing. I will talk to a shop tech this week and see what his comments are.

JPR1968, A tach would be nice as the RPM was a guess, but the stator AC output would get to 70VAC as I revved it up.

PainterD, Thanks for the link! I will check it out..

Oconeedan, Could be. I am certainly not through with the diagnosis phase. I just don't want a regulator problem taking out a stator if I can verify operation and avoid it. I have seen enough posts saying stators and regulators regularly fail all on their own anyway.

Thanks again everyone!

[Darth Underhill]

I have a '93 Shadow, and my shop guys tell me that this model does exactly that: volts go up when idling. Still seems odd to me, but I trust these guys lots.

[rpneal44]

Get rid of the connector between the R/R and Stator on the 3 yellow wire. Solder them together. It is the weakest link in all Shadows!!