Electrical issues - Alternator? Rectifier?

[BIG MAC]

The reason I ask Graham is that my mk1 had a dodgy battery and putting the hazards on somehow foxed the charging circuit into giving just enough for the engine to run. I managed to ride the thing from Chelmsford to Portsmouth in the dark with nothing but hazards...even braking would make it cut out because of the brake lights!

[schlumpf]

Yes, I've just seen Fazerider's post, it's been a very long time since I learned about RMS voltages... The question is: Are those values that that other post mentions (90v!) correct? If I disconnected the plug from the stator to the rectifier and measured that, without load, rather than the input to the RR, would I get them then?

Right, the white wires alone should give a very high reading. 90V AC might be possible. On my FZS1000 it was about 40V (if I remember correctly ..). The absolute value is not important as long as all 3 readings are similar and in the range 30V or up.

Even if all measurements are fine this is no absolute proof that the RR behaves the same while riding.

To narrow down the bug you could still do some more experiments:
- Charge the battery fully up. Unplug the RR completely. If possible switch off all lights (by pulling the respective fuses if no switch is present). This should give you enough power for maybe 30 minutes. Go for some test rides.

- And/or connect your multimeter directly to the battery terminals. Tape it to the tank, or wherever, to be able to observe it while riding.
This should give you a indication whether a voltage drop occurs at the battery.

Any sudden voltage drop at the battery will be caused by a short circuit somewhere in the system. Sometimes it's only a damaged cable insulation, making contact due to engine vibration.

Avoid focusing only to the positive lead. Ground is as important.

In case you decide to swap your RR you can go for almost any other type. They all (not only Yamaha's) work the same way. The only difference is power rating. All modern bikes use Mosfet type RRs. FH012AA is a very popular and reliable replacement.
Only trouble is to find one with matching connector. Maybe unclipping and re-using the old connector housing does the job. 

[Fazerider]

... Are those values that that other post mentions (90v!) correct? If I disconnected the plug from the stator to the rectifier and measured that, without load, rather than the input to the RR, would I get them then?

Yes. That webpage has me slightly puzzled, it states that the AC voltages should be that high on-load which is possible with certain methods of regulation, but not the one that they show as being used by the FZ6.
Shunt regulation simply loads the magneto heavily when the battery voltage gets to the 14.5v region so the AC voltage shouldn't be anywhere near the figures quoted.
Off load, i.e. with the white leads not connected to the R/R, the voltages will increase pretty much in line with engine revs. If you try that measurement I'd keep the revs below 5000rpm as I'm not sure what the insulation is rated at… and be careful, the voltages are potentially lethal since they're coming from a low impedance source.
I still feel that a cheap aftermarket or second-hand regulator/rectifier is the simplest way to diagnose the problem.

[chris.biker]

How long has the present battery been in the bike, and what make is.

The battery is only about a month old [color=rgb(74, 74, 74)]this is the one I bought[/color] to replace the old one when I first started having these problems.Initially it seemed to have sorted the problem, but now it's come back which suggests that the battery may not have been at fault (or, at least, not entirely).

One of the first things taught on any of the training courses I go to is '' just because you have swapped it for a new component it is not 100% that the new one is good.''  I would try changing it under warranty.

[unfazed]

In reply to some of you questions

Yes you can check the alternator in a no load condition, but be extremely careful for the reasons fazerrider has stated.

To do this, ensure you have a fully charged battery.
Disconnect the regulator/rectifier and then start the bike
Check the AC voltage on all three phases (white wires). All three phases should be around 20V AC and it should climb to as you rev the engine and as fazerrider states don't rev it over 5000.
If all three phase rise and fall (within a few volts of each other with the engine revs then the alternator is is doing what it is supposed to be.


In my case the regulator was causing slight over charging occasionally and may have caused the CDI to drop out due to over voltage protection.

[Grahamm]

[quote author=Grahamm link=topic=15299.msg173952#msg173952 date=1416099871]
If I disconnected the plug from the stator to the rectifier and measured that, without load, rather than the input to the RR, would I get them then?

Right, the white wires alone should give a very high reading. 90V AC might be possible. [...]The absolute value is not important as long as all 3 readings are similar and in the range 30V or up.[/quote]

I've checked the Alternator with it umplugged and got readings up around the 80v AC level at 5000 rpm on all three connections, so that seems ok.

Even if all measurements are fine this is no absolute proof that the RR behaves the same while riding.

True.

To narrow down the bug you could still do some more experiments:
- Charge the battery fully up. Unplug the RR completely. If possible switch off all lights (by pulling the respective fuses if no switch is present). This should give you enough power for maybe 30 minutes. Go for some test rides.

After testing the Alternator (admittedly with the headlight and sidelights on) which only took about 5 minutes on a battery that had been charged overnight, I tried starting it again, but it wouldn't go and the voltage was about 11.95v so I'm a bit leery of that idea at the moment, but I'll bear it in mind for later.

In case you decide to swap your RR you can go for almost any other type.

Hmm, that's adding extra variables into the equation. I've put a post in the For Sale/ Wanted section and also asked on a couple of local Facebook Groups to see if anyone has one.

One of the first things taught on any of the training courses I go to is '' just because you have swapped it for a new component it is not 100% that the new one is good.''  I would try changing it under warranty.

A good point and again something I'll keep in mind.

Check the AC voltage on all three phases (white wires). All three phases should be around 20V AC and it should climb to as you rev the engine and as fazerrider states don't rev it over 5000.
If all three phase rise and fall (within a few volts of each other with the engine revs then the alternator is is doing what it is supposed to be.

They did seem to rise and fall appropriately, although I couldn't say they were "within a few volts of each other" as it was difficult to a) rev the bike, b) hold a camera phone pointing at the multimeter, c) keep a light shining on the meter readout and, d) make sure the multi-meter probes didn't fall out of the connector (I think I had too few hands!)

I'm hoping I may be able to get a RR off someone else local to swap with mine and see if that has a positive effect, but I'm not sure right now.

BTW Can I say at this point that I *really* appreciate all the help and useful suggestions I'm getting. It's better than simply chucking it at a garage and getting them to sort it out without even trying myself first :thumbup

[unfazed]

Borrow a few hands  :lol :lol

[Grahamm]

Well I've swapped out the RR for a "new" one (from a breakers, but only done 9000 miles) to see if that will fix the battery charging issue.

As for the "not starting when it's wet", unfortunately despite looking and liberal applications of WD 40 under plug caps and on HT leads, I couldn't see any sparking etc this evening when, after parking it up for a few hours on a humid and rainy evening, it again would turn over but not fire.

I did notice something which I think had happened before, but didn't comment on, which is that when I was trying to start it the LCD bars on the temperature gauge were showing up to half way, then all the way to the top, then dropping to the bottom again.

Now I've heard of rev counters doing funny things if the TPS was failing, but not the temperature gauge.

Anyone heard of this sort of thing happening before?