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Voltage warning light going red

4K views 25 replies 14 participants last post by  greywolf 
#1 ·
I just got through installing a new stator, gluing up the magnets on the rotor and installing a SH847 R/R along with the voltage warning light available from Roadster Cycle. Just before I start it up, it flashes red but then goes green as soon as it's running. The light is always green when running except when I am barely moving and using the turn signals and then it turns solid red. If I turn the signals off and rev it up a little it goes back to green. Is this something to be worried about? I presume the red means that too many volts are in the system and don't understand how the signals could affect the voltage like that (at least not adding more to the system).
 
#3 ·
Here's the write up from Roadster Cycle.

The warning indications are as follows:
Green, light charging fine, The window is about 13.2 to 14.8 volts.
Green and red alternating is over voltage (over 15.2 for a standard battery monitor and 15.0 volts for a Shorai battery monitor, not good)
Amber, (bike running) hook up a voltmeter on your bike and see what's happening with it running.
Red or red flashing means your bike is probably not running and you have your lights on, or if your bike is running there is trouble in paradise and you need to take action not to get stranded.

I suspect that means the red turns on around 12.8V. You've got a charging system problem. (not enough volts, not too much)
 
#5 ·
Not to hijack the thread but sound an awful lot like my day. Maybe similar answers.

(2002 DL1000) I had all kinds of charging voltages including below 12.5V so I installed an SH775 last fall. The voltage was rock steady at 13.8V. Never changed. Great, problem solved. Today, went for a ride with the heated grips on and watched the voltage drop to 12.5V at idle and headed lower. Above idle, it was fine. Turn the grips off and the voltage started to rise. So to me, that sounds like the voltage regulator is working but the magneto isn't putting out enough power at idle. I didn't test it cold, but now I wish I did.

Got home, and checked the voltage out of the stator. Approx. 22V @1500 RPM, 35V @2500RPM, 2 at 65V and 1 at 55V @5000RPM. Sounds like shorted stator windings and/or magnets moving. Pulled everything apart and magnets / coils all look perfect. (see pictures) Coils all test out at 0.3 ohms (cold, didn't test them hot).

So I'm not sure where to go from here. It could be I got a bad SH775. It could be a shorted coil when hot. IT could be something else I haven't thought of.

Ideas?
 

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#8 ·
Except for the stator output readings at 5000 RPM, nothing you report is out of spec or indicative of a problem. Did you measure stator output and resistance with the regulator disconnected? I think it is odd that you saw a difference among the phase readings at 5000 RPM but (presumably) not at the lower speeds. I would repeat the measurement, with an extra hand if needed to manage the throttle carefully while probing the stator output. Also, when measuring continuity (or Ohms), it is good to ensure the stator is not connected to chassis by any significant conductance. You should see resistance in excess of a few MegaOhms.

With no visible damage to the stator, I think it is unlikely to be bad. (Electrical faults induce very high heating stress, usually concentrated on one winding.)
 
#6 ·
At idle engine speed, the magneto does not develop enough output to hold the battery up with incandescent headlights on. I see no cause for concern in the symptoms you report. The red does not mean overvoltage; it means low voltage, just as should be expected at idle. Under that condition, it does not matter whether you have a shunt or series regulator.
 
#7 ·
Do check with a voltmeter on the battery terminals. The place where you connected the warning light may be a little lower than the reading at the battery. Under 12.6V at idle at the battery terminals with a stock load would be unusual.
 
#9 ·
Thanks for the replies. I checked the voltage while sitting and it is 12.9v and while running it is 14.5v. There is no difference when I turn on the grip heaters and auxiliary LED lights at the same time. I also have LED headlights now. I guess I'm ok then
 
#10 ·
The measurements were made with the stator disconnected from the r/r. Measuring at 5000 rpm was tough single handed. The rpm may have gone down when I looked at the meter.

The voltage was good every time I stopped in the first 30 miles and then bad every time thereafter. I'm surprised that the output is going down when hot. Is that normal?

I'm also surprised that at bone stock, just adding heated grips is too much for this magneto.
 
#11 ·
The measurements were made with the stator disconnected from the r/r. Measuring at 5000 rpm was tough single handed. The rpm may have gone down when I looked at the meter.
The ratio of the 5K rpm voltage to the voltage at lower rpm was off, too. I would throw out those values and retake them, carefully, before getting worried about the stator readings.

The voltage was good every time I stopped in the first 30 miles and then bad every time thereafter. I'm surprised that the output is going down when hot. Is that normal?
I suspect that changing idle speed with engine temperature is more of a factor than anything else. Before assigning significance to those "good"/"bad" levels, I would control for idle RPM. Furthermore, the fact that output drops at idle is unlikely to matter. From my measurement, analysis and simulation of the magneto and R/R, I know that not quite supplying even the stock load at near-idle speed is normal.

I'm also surprised that at bone stock, just adding heated grips is too much for this magneto.
If that's true at cruising speed, then maybe there is a problem. But I'm not seeing enough, yet, to determine that.
 
#13 ·
I love my led battery monitor. I never have to look at it. When it goes yellow (idling) i turn off the heated gear or a headlight.

Sent from my SM-T700 using Tapatalk
 
#15 ·
Since I didn't find anything obvious inside, I'll put it back together and take some better measurements.

One last question. When I took it apart, the large primary gear fell out and I didn't see where the thrust washers went. I presume (since I only found 2) there's one in each end of that gear when reassembled. Can someone confirm?
 
#17 ·
My Signal Dynamics Heads-Up VM does the same thing. At idle (stop and go traffic, etc) generally it will turn red, then back to green when rolling again. If, in fact, it doesn't turn back to green then I know there is a potential problem.
 
#18 ·
I have the same LED voltage monitor, and I got freaked out at first because what they call amber looked awfully red from where I was sitting. I can now tell the difference. I have the monitor connected to an aux connector in the cowling, rather than bringing it back to the PC8 or battery, so the volts are off a bit and I regularly get the flashing red when the bike is at idle. I went with the Compufire R/R so I'm sure it behaves a bit differently, but I regularly get the monitor flashing red at me at idle after things have warmed up. I don't worry about things unless the monitor doesn't recover to solid green once rolling again. Haven't had that happen or had a dead battery in well over a year, and that's on a battery I was ready to write off, because it had been jumped by cars three times. Anyway, like I said, you're probably seeing the amber as red, but don't sweat it even if it is red.
 
#21 ·
As a reference point, my volt meter is connected direct to my battery. I have heated grips, led brake and running light, led headlights and aux power shelf

With ignition off the vm reads 12.6
At idle it stars at 13.8 and rises to 14.5
Running it sits on 14.6 or 14.7
With grips on it drops to about 14.0 at idle.
 
#25 ·
I was stuck in a traffic jam yesterday and the amber light came on. According to the instructions I need to check the voltage with a meter but it doesn't state why. Is it too high or too low?? I just ordered a voltage meter that shows numbers. When I checked this morning I got 12.9v while sitting and 14.5 while running. I did smell a weird smell while in traffic, so I hope my new stator is ok
 
#26 ·
Amber just means the voltage at idle is marginal for charging. That would be indicated by the 12.9V with a warm idle, just above break even. Don't be concerned unless you see amber while running above 2500rpm or red at idle.
 
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