Stator

[Pukmeister]

Were the original insulation values measured with a basic multimeter, or a 500V/1000V Megger (insulation tester) ?

Insulation breaks down at higher voltages and with heat, which is why insulation testers are high voltage.

If the output wiring from the stator is getting very hot, the fault is most likely poor insulation elsewhere eg voltage regulator/rectifier ?

 

[Santa-2512]

And in being helpful to the OP how would you propose to measure this???

Clamp meter round the output wire (s) set to amps, start the bike and and observe the amps at idle and then at 4k

Turn eveything electrical on and repeat



The general purpose of these threads is to try and help the op with there problem

Yours seems to be taking potshots at people trying to help - !

Tell me what have you brought to this thread ?

 

[Pukmeister]

When you say “no continuity” between the stator phases and ground, can you quantify that in Megaohms ? I would expect at least one Meg of insulation if not better.

 

[Hann]

I don`t think there is anything wrong with the stator which appears to be in good shape according to the test measurements that have been done - the most telling measurement being the battery voltage when the engine is idling, the OP`s measurement of 14.3V tells all, if the stator was compromised in any way such as shorted coils or insulation breakdown to earth this would show itself in the battery charging voltage. Failing stators typically show voltages of around 12.X across the battery when they have shorted.
Duff stators usually show a lack of charging/low battery voltage, this is not the case on this bike.

OP was the replacement reg/rec new or a known good one?

 

[RadioFlyer]

Clamp meter round the output wire (s) set to amps, start the bike and and observe the amps at idle and then at 4k

Turn eveything electrical on and repeat



The general purpose of these threads is to try and help the op with there problem

Yours seems to be taking potshots at people trying to help - !

Tell me what have you brought to this thread ?

More bad advice. What "output wire(s)" are you referring to? Thoroughly ambiguous.

I make no apologies for pointing out incomplete or inaccurate advice or outright misinformation. The general pupose of these threads is indeed to help with problems being experienced by other members. Posting incomplete or inaccuate advice or outright misinformation does nothing to help and has every potential to mislead and confuse.

 

[Spooky]

I think some people are confusing the way a stator system works on a bike compared to a car alternator type. The stator produces 100% capacity 100% of the time, the limiting factor being rpm. Hence why manufacturers can give definitive outputs at specific rpm. It’s the reg/rec to battery that is load dependant with excess being lost. The gs reg/rec looks like a shunt type based on the heatsink so the excess is lost as heat.
So I think the hot stator wires is normal and the melted connector was a result of high resistance in the connector itself, probably from age, corrosion etc.

 

[hiwfrs]

Found some literature for testing the stator with a 12v 55w headlight bulb, it states put each side of the bulb to any 2 of the 3 stator wires, start the bike & check for volts ac, the bulb should light up however my bulb blew instantly. Can’t understand how a 12v bulb wouldn’t blow if it’s being supplied with 24v ac (as tested with meter) or is this correct & the stator output is to high

 

[DJ123]

i'd expect it to blow, as it's being supplied with twice (and then some) the voltage its rated for.

The multimeter test is what counts.

 

[hiwfrs]

Hopefully this has worked & you can see page 9 & 10

 

[Spooky]

Your stator output is determined by the number and gauge of the windings used by the stator and the magnetic field determined by the strength of the magnets on the flywheel and rpm. The only thing that will increase stator output is rpm. The other factors are fixed unless they fail in which case output will reduce.
Any heat above the normal function will come from increased resistance rather than output. Any over voltage scenario will be post stator.

 

[hiwfrs]

 

[RadioFlyer]

With a shunt type regulator the sum of the current consumed by the bike plus the current shunted by the regulator will always be whatever it takes to draw the DC voltage down to the regulator's setpoint. As RPM increases the regulator will shunt more current. The shunted current adds to stator heating which is why some convert to a series type regulator to increase stator life.

As mentioned earlier the resistance encountered at the connectors can result in localized heating which can be enough to melt the connector(s). For this reason it is a good idea when installing these connectors to both crimp and solder the pins.

On most bikes with burned out stators the entire stator is pretty much uniformly blackened however the early wethead failed stators always show heating only at one or two poles indicating a definite hotspot.

A good choice of series regulator is the SH847. While it is plug compatible with the OEM shunt type regulator it is physically larger and fitting it into the space available requires some adjustments to the mounting scheme.

Stators have been burning out on small motors with Permanent Magnet Alternators for decades. Shame on BMW for not overengineering the stator if they wanted to bury it in the engine. The repair of a burned out stator on the wetheads is very expensive as the engine must come out of the bike.

 

[Spooky]

Can you clarify the process of increased shunting adding to stator heat, are you referring to reactance ? Reactance only really exists in the stator windings itself and yes has the potential to generate heat, determined by frequency/rpm. But inductance also increases with the same factors, in effect acting as a self regulator. I’m guessing the brains at manufacturers do their sums.

For the benefit of the op the crux of the system is that the unregulated output will increase with RPM, and the stator output will be the maximum value it can produce at any given speed and the load/heat is pretty much entirely resistive. I do think a lot of stators setups have little margin. The insulation on the windings can only run at the output they mostly do for a finite time. Denso had a major problem with 500w systems mostly on Honda’s and Aprilia’s. Their fix was to change the flywheel ( reduced strength magnets) to reduce stator output to 370w giving the system much greater margin before failure.
The series reg switches the stator in and out of circuit instead of shunting excess. Whilst that has some benefits, I’m not convinced they do much for the stator. Been there re the Denso experience above.

 

[RadioFlyer]

I am referring to I squared R losses/heating. There are many posts where the difference in stator temps between shunt and series regulation have been measured. Similarly there are posts where the difference in stator current has been measured. Reactance and core saturation do play a role in limiting current but not enough to limit current to levels that mitigate heating becoming a longevity issue.

 

[Pukmeister]

The load on the motorcycles electrical system is almost exclusively inductive rather than capacitive so I doubt you would see reactive power being generated within the stator windings, power factor should not really come into consideration on such a simple system. Being permanent magnet excitation its output will be within a small range, the excess being shunted for control method as already suggested.

 

[hiwfrs]

What amps is the alternator delivering at - Idle & 4k (+-100rpm) you should be seeing 28A at idle & 48A at 4k

 

[hiwfrs]

Hi
Managed to do more testing
3 stator wires have 30amps idle @ 32amps at 4K. Batt neg has 7 amps running, I have put a 12v batt thru both poss & neg at reg plug to other end at batt with a 12v 55w bulb in series & both leads get 5.87amps. Battery gets 14.3v when running, stator wire get to 95deg C in a couple on mins running. I’m at a total loss

 

[Spooky]

Not sure why you are lost to be honest. Everything seems normal and stator wires that are too hot to touch (and melting connectors with age) is common to most bikes that are sporting 500w stators. The cause of the connector failure is 99.9% of the time due to high resistance in the connector itself. If it were me I would fit a new connector ( of decent quality ) and away you go. Then have a look periodically to see if all looks ok.

 

[Santa-2512]

Simplest way, change the connector if it's still getting that hot, there may be an internal fault with the stator

It's clearly not 100% your 4k values are 16A down (even assuming tolerance errors in your measurment equipment )

The 2013 units are known for having Stator failure

 

[Spooky]

Are the stats re the stator earlier in the thread correct for a 2013 bike with the 15 winding stator ? Seems many are quoting 35 amps for that era bike, not far off the 32 mentioned above. The later bikes have a 21 winding stator which I suspect has a higher rating to give it some overhead.