Here is a waveform from a permanent magnet 3 phase alternator - see picture. I want to check the output with the stator loaded. Do I check with one channel connected to 1 phase at the regulator or should the ground lead be on battery ground. Or does it not matter, with one waveform showing rectified output and the other not. The stator itself has a floating ground?

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Never worked on anything like that so not entirely sure what you are after but:

Your 4425 has a capacitive barrier between the channels and the USB ground.  AC can cross this barrier (DC cannot) and load the signal or cross it over to another channel.  You can do DC differential measurements up to 30v with the 4425 but AC can cause issues.  I don't think you would hurt anything but it may affect your results.

James, is the wave form on the drop site, I don't see it here.?

StitchB

Thanks for chiming in guys. I am just trying to figure out which is the best test to determine what is causing a charging problem. If you look at my attached file you'll see that I have a channel on each phase at the regulator rectifier with all the channels neg on battery ground. Everything is hooked up so its a loaded test. At the first part of the capture everything looks fine, then it drops out phases. I'm not sure what this is telling me. Is it the stator or reg/rec? I would think stator but if you check continuity on the stator its good and no shorts to ground. The stator also puts out good unloaded AC voltage on each phase. The diodes check okay in the reg/rec. So I am at a loss, not sure what that waveform is telling me - anyone?

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James H wrote on Jan 9^th, 2018 at 1:46pm:

So I am at a loss, not sure what that waveform is telling me -

James, yeah, kicked this around myself for a while and then going to a moffsett RR.

Noted in my captures all 3 channels stable, the @ RPM spots misssing as voltage output rises, then all come back when down.  Don't know if this is the Stators ability to drop some output as voltage becomes too high, would think that is the RR job.

First file is KLR, second is DRZ 400, both show the same drop outs on channels, and both in good working order.????

Again, I have seen very few captures of the systems, again the bike world just does not do it...........so not much to go on, but I know the mosfet RR is a better deal than the original RR as it turns thinks off rather than just dumping the extra down to a heat sink, JMO, and had too read a lot of various blogs to get too know it.  I have some more captures from my DRZ 400 I will chase down.

StitchB

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Larry, thanks for the captures. So I am not going crazy as I see the same weirdness in your captures. I'm really struggling to understand why this is and if it is an actual problem/weakness or not. I going to test more bikes and see what I come up with. I attached a waveform from a 600cc Kawasaki and you can see it looks like what I think should be normal in comparison to the others. I was hoping some electrical genius on here would have an idea.

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James do you have the captures on the drop site?  I work with Motor Drives that kinda work on the same principle here.  What are the symptoms? :)

I'm at work and I still can't get Acess to the forum on my laptop but I can still get to the drop site with my laptop. :)

Hi busjockey, posted them up, thanks for having a look. There are 3 up there. One is from a 600 Kaw that charges fine and the waveform looks good and consistent as to what I would expect. One is a CM450 that charges on idle but doesn't as you rev it up. Voltage is okay but amps drop to 0. The diodes in the reg rec check out, the stator has good unloaded AC voltage and it is not shorted to ground....but the waveform shows dropouts in it?? The other is a EX300 Kaw and it had a weird problem with missing at high rpm. I found the AC ripple was high but the reg rec checked out good as far as the diodes. If I disconnected the alt it ran fine. Turned out the stator had high resistance to ground. That waveform looks like crap too. So im just trying to get a handle on what is bad and what isn't and is it a faulty stator or a faulty reg rec. Larry posted some wave forms from his bike that also look bad but apparently were not.  :-/

I'll take a look tonight James. :)

James, opened your site and noted one capture that was obviously had dropped on leg totally, and was replaced.

I'm going to venture a guess as I did not see any files showing idle, then @ say 5,000RPM.  Like I stated there is not enough input from players too know here but the drop outs on my captures on any off the legs, and not always congruent are at higher RPM. 

On mine all the signatures were good until up off of idle, meaning IMO @ idle all legs were pulled through the RR max. Then when up @RPM see some off the signature lower or in spots and maybe this is the RR choosing where ever to limit out put of Stator At the other side. I am not an electrical engineer, but know that my system both looked this way and both are working perfect.

Now that said, with not enough input from brains larger than mine, maybe these stators are working but during higher RPM there is enough  vibration and moving of clearance between the surfaces to create this look, I just don't know????, but maybe Busjokey could expound on it.

I know I went to the moffett RR because old style just works @ 100% then dumps off voltage through heat sink like the resistors on heater fans in cars,, but moffett actually turns off charge when needed. I read a ton on it and that is what I gleaned from it. This is why I feel you see the dropping on any of the 3 legs during max output which is keeping it At about 14/15 volts. Any body can feel free to disagree, at is just my UNEDUCATED guess.

StitchB

All I know is mine work perfect, but the one screen of yours has totally lost a leg.

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Larry, I see where you are coming from but being that these systems use a shunt regulator they are just pushing all that excess to ground, no? I have heard of a series style regulator which I believe works on the principle of shutting off the current but I do not know if there are any motorcycles using them. But then again there is no other explanation to what we have both observed. I'm going to do some more digging. Let you know what I find.

James sorry I didn't get back to you sooner.  Can you tell me how many notches there are on the rotor?  Also I recommend hooking up a current clamp up to each leg and see if it's because of low current/low voltage or high current which is drawing the voltage down.  I would hook up a current clamp to two of the legs and a volt channel on each one and see how it is reacting.  Then if you can give me the rotor notch we can calculate the rpm and we can figure out the phase angle for the 3 phases.  Since you have 3 it should be 120 degrees.  Then we can tie this together and see if you potentially have some sort of mechanical issue inside this alternator.  Bearing wear will throw off your phase angle and can cause a voltage output issue due to too much distance from the  rotor and field causing a field strength problem thus less Voltage.   :)  Try this and get the rotor notch info for me if it is available. :)

Shoot is their a problem with this bike or are you just experimenting? :)

James H wrote on Jan 11^th, 2018 at 11:29am:

shunt regulator

James, that was always my question as some use a shunt, and some a moffset, and like stated the shunt just works the lips off the alternator all the time, and the Mofsett shuts it down when it has enough. Just what that looks like is why you and I are tapping in and looking at these as there really is I have found no DSO captures from anybody, and if you aren't getting them on AN, then they probably don't exist, IMO.

Sollllllllllllllllas bus jockey stated can try also looking at amperage but none of the systems I have sent to you were failed, they all worked.  He intimated as I did that depending on how tight the system is and how much slop there is in the clearances you might have strange looking signals, I just don't know.

The one picture of yours with a blue leg just gone, well..............pretty much must gone.

My thought on a couple of my capture is.................you will note that there is signature there, just not tall but very concise, that is why I was thinking regulator is capping it at about 1.3 volts, again I didn't design it but over time we will get a better picture.

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James can you share anymore service info on the Alternator and regulator? :)

I have a couple of bikes I'm checking, one with a problem and one without. I am going to do some more testing tomorrow and see what I can figure out. I'll post my findings when done. As to busjockey's previous question it has 18 poles and the stator is mounted in a cover at the end of the crank. The magnetic rotor is attached directly to the crankshaft. See pics. You can see where the stator from the 300 Kawasaki capture has one phase with a wire somewhat burnt. Motorcycle 3 phase stators in general put out aprox 15 to 100 volts AC unloaded from idle to redline. They are all "wye type" floating ground.  The majority use a full bridge rectifier in the same box as the regulator. Most regulators as Larry expanded on are shunt type meaning all excess voltage goes to ground. They are current limited by their design.

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How many notches are in the rotor?

12 I believe  but it is hard to tell because it's all encapsulated