Wassel unit faulty? EDIT: probably not

[Nerdy Norm]

Sorry to resurrect my old thread, but I just had a chance to run some more tests.

With everything connected up, these are the voltage readings I get at the battery:
Without engine running: 12.3V without lights on, 11.9V with lights on
With engine idling: 12.5V, 12.0V
With engine revving: 12.5V, 12.0V

Does this sound normal? I would have thought that the voltage would increase with revs.

If I take the battery out of the circuit altogether (to simulate a flat battery), the headlight is very dim, even with the engine revving. It's much dimmer than it was before carrying out the Wassel conversion. However, since it's only getting around 3V from the red Wassel unit wire, I guess that's not surprising.

In summary, it would seem that as long as I charge the battery before each trip (I usually ride with the lights on all the time), I should be OK. But I'd prefer for the lights to still work normally direct from the Wassel in case of a battery issue.

Am I expecting too much, or am I missing something?

[ArmandTanzarian]

That doesn't sound great. If the voltage across the battery isn't at least 13 to 13.5 volts with the engine running it won't charge properly

[Nerdy Norm]

It doesn't seem right to me either.

Since the stator output seems OK, is there a way to test if the Wassel unit is working correctly or not?

As an aside, I notice that other people have had the same problem with the Wassel unit, and as far as I can make out, there was no solution available. See this thread for example where the author tested several units, all of which only put out very low voltage:
http://scooterotica.org/forum/viewtopic ... e&start=60

[Nerdy Norm]

Quick question - without the engine running, should the 2 yellow wires coming from the stator be earthed?

Mine are (tested using a multimeter's continuity beeper).

[rosscla]

The two yellows should NOT be earthed directly they should be connected to your wassell which in turn should have a red to your battery / loom and an earth


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[Nerdy Norm]

Maybe I should phrase that differently

I didn't deliberately earth the yellow cables, I just observed that when tested with a continuity tester (one end to the cable, one end to an earthing point), it beeps.

Another member has been kindly giving me some pointers by PM, and since the yellows are earthing for some reason, it sounds like they are maybe pinched behind the stator.

[rosscla]

Definitely shouldn't beep unless there's something shorting or the stator has not been done right. If disconnected you should get low resistance between the two yellows and no continuity to earth. You might get continuity via the rectifier if they're connected.


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[Nerdy Norm]

I measured the resistance across the two stator yellows, and there is none. I wasn't sure which scale to use on the multimeter, but they all gave no reading, except for the smallest setting, which read something like 00.07.

I'm also confused as to how the yellows seem to be earthed with the engine off, however once the engine is idling, there is around 11V when I put a meter across them. Surely if they are earthed, that voltage would run straight through the frame, causing all sorts of problems?

[coaster]

I measured the resistance across the two stator yellows, and there is none. I wasn't sure which scale to use on the multimeter, but they all gave no reading, except for the smallest setting, which read something like 00.07.

I'm also confused as to how the yellows seem to be earthed with the engine off, however once the engine is idling, there is around 11V when I put a meter across them. Surely if they are earthed, that voltage would run straight through the frame, causing all sorts of problems?

If the yellows are disconnected from the wassel unit then a short to the engine/frame will have no effect. With regard to the resistance of the lighting coils, as already mentioned, this should be VERY low as in almost a dead short and probably only measurable with a fairly decent meter. This is because there are relatively few turns on the coils and a heavy gauge wire is used. As already advised, there is almost a nipped wire behind the stator, easily done

[Nerdy Norm]

I meant with everything connected up - would that not have an effect?

Sounds like I need to get the flywheel off