Alternators need a minimum speed to turn their output on. A loose belt could do this, though short of someone installing the incorrect size or overstretching the belt on install that shouldn't be possible. Maybe a broken cord inside the belt or a loosening pulley. After that the only other possibility would be a dead rectifier, so one of the 3 phases is producing no output, which would make the alternator not have enough current output at lower speeds.

Check the belt and pulleys. If they are OK, the alternator may need to be replaced or serviced. The rectifiers are trivial to replace and cheap, but almost nobody does that anymore. You will need to find an alternator shop that is willing to open the alternator to replace it. Given that your charge voltage is correct at higher engine speeds, the regulator is probably fine.

Might be a loose connection or ground, but given how the voltage always falls when the engine comes to idle I'd bet on the two items above. Your alternator produces more current as it's speed increases. They are sized to make just enough power to run everything on the bike at idle and keep the voltage high enough to prevent battery discharge, which would be 12.8-12.9V.

 

No alternator or belts on a liquid cooled bike—has a stator. Not positioned for easy service so do some diagnosis before diving in.

https://www.r1200gs.info/threads/tell-me-i’m-wrong…-please-2014-stator-failure.55510

 

Gak. Missed that it was a water cooled bike. At least that means the diodes are external to the stator and can be checked, as can the stator. Hopefully it's not a bad stator.

 

I found this helpful diagnostic test (Diagnosis and repair of charging system (R-series, '13 on) V1.0.pdf (ukgser.com)) for model years 2013 onward. Will allow me to test the diodes to verify if the issue is with the Regulator/Rectifier or with the Stator... Unfortunately, today I learned that my model year bike (2014, built 11/2013) is the last year before they replaced the stator with a new design that doesn't overheat as easily, so I am starting to get nervous... Will report back this weekend.

 

On the ride home today, I noticed if I increase my idle speed at the light from about 1200rpm to 1800rpm, then a charge is being put back on the battery… Unfortunately, 1200 rpm is about normal, so shouldn’t need to run higher rpm to charge the battery.
Will run the diagnostics and report back.

 

OK, so I finally got the time to run some diagnostics using the ukgser link above.

• Battery tested OK. I left it off the tender for 3 days and the voltage only dropped to 13.06v, so there does not appear to be a parasitic draw
• Section 4.2, Step 11 expects the battery to remain at 14.2-14.4v with the engine idling. I already knew this test would fail as I've seen the voltage dropping while idling. The voltage continuously fell until the warning light comes on (12.3v or less).
• Step 11 continues with a no-load DC output test at the regulator/rectifier by disconnecting the 2-pin connector at the unit and starting the bike
  • Test states that if the stator were faulty, the voltage across the regulator/rectifier pins would be lower than 13.8v
  • Test states that if the voltage rises to between 14.2v-14.4v at idle speed then there is a possibly faulty regulator/rectifier.
  • with the engine at idle, the output of my regulator/rectifier was 14.92v-14.95v (?!? doesn't fit either of the two outcomes above)
• I proceeded as though the 14.95v reading was a fail of the first condition since the voltage rose well past 14.2-14.4v at idle speed
• Section 4.4 Testing the voltage regulator/rectifier
  • As soon as I disconnected both of the connectors, oil started dripping out of the area for the alternator connector (is that normal?!?)
  • Test 1: PASS, resistance readings were all within spec: 474 for all three pins (expected value: 460-480)
  • Test 2: PASS, no continuity present
  • Test 3: PASS, no continuity present
  • Test 4: FAIL?,resistance reading of 100 for all three pins, expected value: 103-105.
    • I would have expected this to fail more spectacularly than 3-5.
• I decided to test the Alternator anyway while the regulator/rectifier was disconnected...
• Section 4.3 Alternator Test
  • Test 6, continuity between all 3 terminals: PASS
  • Test 8, the resistance read between all 3 windings was 0.1 for all three, expected value 8 ohms (PASS?)
    • I had it set to Auto scale. When set to Ohms, 0.1 was the only reading I could get, so I suspect the value was rounding up
  • Test 9, PASS, no continuity between each of the 3 stator pins and Ground.
  • I stopped here as I do not have a light bulb to do step 10, reading voltage off alternator with small load

If the output at the pins of the regulator/rectifier connector at idle is 14.9v, then why is my battery not being charged at idle?
Perhaps there is a limiting circuit (ECU?) that is preventing harmful overvoltage from reaching the battery?
Did the regulator/rectifier test above fail?
Why is oil pouring out of my regulator/rectifier at the alternator connection terminals?

Any advice on how to proceed next?
Thanks,
Matt

 

Re-tested the stator resistances with a different multimeter, just to take that out of the equation. Similar readings of 0.3 Ohms across all three stators (expecting 8 Ohms). I decided to start the engine up and read the AC voltage between the 3 stator pins and got 13.3-14.5 volts AC between pins 1-3 and 2-3 (expecting 60v - 70v AC) and got 0v between pins 1-2. So, things are not looking good at the moment...

 

To test the resistance of the stator windings you need an accurate meter capable of measuring such low values. Many cheap meters won't give you valid readings at low resistance values. Seems unlikely that all 3 windings have failed in exactly the same way.

When measuring the voltage on the disconnected stator windings, the voltage should rise as the motor speed increases, could get as high as 50-60V with no load applied. 13v at idle seems low.

All that said, the fact that you get 0 volts on pins 1-2 means that 2 of the windings out of 3 are shorted since you get continuity between all pin combinations. If you are absolutely certain that there is no output on pins 1-2, the stator needs to be replaced.

This would match your symptoms, in that the stator is only producing 1/3 the output it's rated at, so at idle it cannot keep the voltage high enough. When the motor spins faster, the remaining winding is making enough power to push the voltage up into the acceptable range even with the load the bikes electronics present.

Oil leaking out of the stator electrical connector indicates that the seal on the wire end inside the motor has failed and engine oil is being pushed through the wire out to the connector. That in and of itself isn't a big deal since oil is a good insulator, though the sealed connector at the regulator means that the regulator may start to fill with oil over time as it's connector isn't hermetically sealed at the pins to circuit board.

If you go to replace the stator, be aware that the service manual indicates that the M6 bolts that hold it on have Loctite 270 (red), which may require heat to get them removed.

Also, be aware that you are one winding away from zero stator output and that last winding is now being run much harder that it normally would.

 

The second meter I tried was a Fluke, so not a cheap meter, per se. I plan on replacing the R/R while I'm in there just to be sure everything is in top-top shape and not 10 years old and waiting to fail.

Since there is voltage on 2 of the 3 pins, shouldn't that mean 2 of the 3 stators are working (2/3 the rated output)? Just curious. Whether 1/3 or 2/3, broke is broke. Thanks for the tip on the stator M6 bolts. I have a heat gun I can use to encourage that Loctite to release. I read somewhere that there is a special tool required to take the clutch off the front... something about the clutch needing to come out in order to disengage the gears/shaft out the back. (?) I'll be getting a Haynes manual as well, so I'm sure they will make things clear.

 

Motorcycle charging system - Page 1

Motorcycle charging system - Page 1

www.eevblog.com

Take a look at this diagram. It's shows how a typical 3 phase stator is wired. If you look at the Y configuration the coils are connected in, to get 0 volts across two of the pins, the two coils you are measuring across both would need to be shorted. When you measure across any two pins, you are actually measuring across 2 coils in series. If one is shorted, the other coil still has output. The voltage would be 1/2 of normal, but you would not see 0.

As to why you see 0.8 ohms across any 3 pins, it's entirely possible that there is a low grade short in all the coils. Basically like a fine wire shorting across the coil. The meter probes with a very low current and reads voltage drop when measuring resistance. Such a low current will not appreciably heat up something with a very small cross section, so it reads it as a short. When the stator is running and making power, it makes enough current that it heats up the short, raising it's resistance and turning it into a much higher value while under power. Same principle as a light bulb. Measure that with a meter and you see less than an ohm. Measure the current and voltage while it's on and it works out to 20-100 ohms or more.

I suspect the stator failure is a bunch of burned up insulation and oil creating low resistance paths between the wires that make up the windings. It's a common failure mode in transformers and motors as well. Once a single spot has an insulation failure, it creates heat or even an arc, leading to further insulation failure until the entire winding is shorted between all the wires or the core.

 

Thanks for the explanation.
I guess this means I’m riding on borrowed time, or a countdown clock until it fully fails. Will get the parts on order stat!