Electrical problem diagnosis...

[edgey]

Hey again all,

I was hoping to complete this one without posting a thread but alas I need a little direction from the gurus.

First off, the problem: I was riding home, not doing anything erratic rev-wise to my knowledge, and bike engine suddenly cuts out, all other electrics are fine. I pull over and try ignition again as you would and there is a rather audible clicking noise for as long as ignition is held.
Once Mr.AA gets me back home that night I get the battery on charge. Optimate 4 now indicates battery is 'green LED/fine' so i once again try ignition and voilà! bike runs... So onto further testing using previous threads and Rick's charging system checklist (from forum document library).

Bike idle, battery reading is 12.1V (a little low I believe), at 5.5k revs reading is 12.7V (definitely too low).
Then I checked the 5 pin connector on reg/rec unit and it seems fine, nothing untoward.
Next is where the alternator plugs into the loom, all readings between all 3 yellow wires are between 0.1 and 1 ohms, all readings between each wire and a frame bolt read infinite.

Summary: The only untoward thing so far is low battery readings, given how the engine just cut out whilst riding would this indicate either knackered battery or one set of coils in the alternator has burnt out? Or Both? (not sure how old this battery is, off top of my head I believe it's an Exide YTX9-BS)

Cheers,

Edge.

[edgey]

Just did a little more research on here and found another thing to test:
Turn bike on, get revs to 5k & test voltage between the 3 yellow wires at the alternator plug & test volts which I believe should be in the region of 50V. I tested between each wire (A&B, A&C, B&C) in a similar fashion as I did earlier when measuring the resistance (all about 0.5 Ohms) however I failed to get a voltage reading for any. I also checked between battery negative & then each of the wires and still nothing. Does this indicate it is probably the alternator? How would I diagnose further?

Cheers.

[CMSMJ1]

get the cover off and look at the alternator. sounds like it is fecked.

[speedy231278]

If the voltage increases from idle to 5K, then the alternator is doing something, so you can't be getting nothing from it at all. Silly question, but as you've checked between the yellow wires and the battery which is not the correct way to test the circuit, you are actually aware that the alternator output is AC volts, not DC? You need to test the yellow wires with your meter on AC, or you'll not get the right reading (or probably any!).

If you did have the meter on AC and checked between a yellow wire and the battery negative, you should get nothing either, as that's connected to earth, which you have successfully tested earlier to have infinite resistance, so no current can flow. If you did have it on the DC scale, go back again and see what you find. Mid-high 40s is what you are looking for with the alternator disconnected.

[bikemonkey]

If the voltage increases from idle to 5K, then the alternator is doing something, so you can't be getting nothing from it at all. Silly question, but as you've checked between the yellow wires and the battery which is not the correct way to test the circuit, you are actually aware that the alternator output is AC volts, not DC? You need to test the yellow wires with your meter on AC, or you'll not get the right reading (or probably any!).

I made this mistake when I first tested my charging system, and I sometimes still forget to use AC

[edgey]

Yup, had lost my multimeter's manual but managed to find an online .pdf, sure enough I was still on DC setting, not AC, what confused me is that the manual explains how to read DC, with the AC reading page saying "same as DC" but with a small picture of the dial in a different location, clearly meaning same protocol as DC but with dial in this range. It being months since I'd read the manual my brain thought the multimeter had one range for both AC/DC, only 3rd time I've had to use it so still learning.

Anyway, between A+B, A+C, B+C (yellow wires), all read:
Idle = just shy of 10v
5k = 43v

These readings are a bit shy of what they should be I believe, what now chaps?

[bikemonkey]

They check out ok, I'd be testing the reg/rec next.

What is the state of your charging system wiring like?

[edgey]

I haven't saw anything dodgy in the wiring & connectors, no heavy blackening or burnt looking items, alternator plug has a tad bit of grime which wiped off easily and didn't affect readings. I just checked the readings of the 3 yellow wires in the reg/rec plug, readings are similar to that at the alternator plug in my last post.

[bikemonkey]

I meant testing the functioning of the reg/rec, guide to all your electrical testing here: http://www.electrosport.com/media/pdf/f ... iagram.pdf

[edgey]

Well that diagram is rather boss. Downloaded that badboy.
Set multimeter to DC 20V. All plugs on bike connected. Bike idling.
Black lead to battery +ve, Red lead to white/red RR wire = 0.02V
Red lead to battery -ve, black lead to green RR wire = 0.03V
Both below diagrams stated 0.2V.

Following that diagram I get all the way to the bottom where all 3 of my readings are equal enough but all below 50V which the diagram indicates Stator is at fault.

Does that conclude my problem to be the Stator? Should I go about replacing this or the whole alternator (is it one of those things where it's best to replace all at same time)?
No time this evening to open up the alternator casing.

Thanks for the help so far guys!