How do you check if the alternator is functioning properly.

Woody, did you mean that the other way around? This is the biggest and baddest series SCR rectifier, rated for 35A without cooling, and 50A with. I could maybe fit it into fairing and attach a fan as well, but that's too much work.

yes I did ... sorry that was the beer talking ...........

SHUNT = HOT
Series = cool................

As an update, I finally installed a series rectifier. I figured I could wedge in the SH847 above the stator cover, but that was too much work, and would have needed a longer cable. I decided to screw it, and went with a SH775 polaris unit. The thing fits in the bracket available for the SH020. Pics to come after I am sober. Tomorrow I am going for a ride, to see whether the 1/2 HP gained at the low end is going to make a real world difference Well, more importantly, I want to see if my drunken crimping works in real life.

pic's or it didn't happen

Looks like the wife's bike decided it didn't want to play any more... 58,000KM

Continuity between the yellow stator wires
- Engine off (battery connected)
Wire 1-2: 2
Wire 1-3: 1.7
Wire: 2-3: 1.4

Continuity between the yellow stator wires and earth (engine casing)

- With battery disconnected:
Wire 1 - ground: 1.7
Wire 2 - ground: 1.7
Wire 3 - ground: 1.3


Voltage

- Motor running idle, rectifier unplugged:
Wire 1 - 2: 24V~
Wire 1 - 3: 24V~
Wire 2 - 3: 24V~

- Motor running @ 4.000 rpm, rectifier unplugged:
Wire 1 - 2: > 61 V~
Wire 1 - 3: > 61 V~
Wire 2 - 3: > 61 V~

- Motor running idle, rectifier plugged:
Wire 1 - 2: 8V~
Wire 1 - 3: 7V~
Wire 2 - 3: 8V~

-*-*-*-*-*-

So if I'm reading this right... I'm looking at a dead rectifier and a dying stator?

Your stator looks fine. Either it's working fine or all three phases are equally messed up (very slim chance). The stator voltage with the rectifier plugged in is somewhat meaningless. The RR will cause a voltage drop across the stator plugs when it is working. What is the voltage between one of the red and black leads from the other end of the RR? Depending on the model year, you should see 13.8 or 14.4V across them at just above idle, and 14.4 at 5k rpm+. These rectifiers aren't the greatest things around, but they have been ultra reliable.

Are you trying to troubleshoot a dead battery? Those things only last a few years unless ridden regularly.

Yes, I concur, I think your conclusion is spot on.
Here is an unsolicited tip****DO NOT WASTE YOUR TIME AND MONEY on an OEM R/R for replacement. A series style R/R like the CE-605 is the way to go====will make the stator run cooler, thus longer lifespan, will itself run cooler, therefore less voltage drop, and typically provides MUCH smoother and more consistent voltage regulation.
For reference to corroborate what i have just said, check out JR Woodens thread Oscilloscope Traces in this forum.
All the best,
THUMPER>>>>>>>>>>>>>>>>>>

Battery is a year or two old... Was working fine until this morning.

Wife had been on the road for about 2.5H when the motorcycle stalled. (Dashboard first went crazy).
Got a boost. Motorcycle would run for a few minutes, but when stopped, it wouldn't re-start.

Towed it back to the house. Started it with another battery, check voltage at the battery, no difference between idle and 4000RPM

-

How fast do these RR heat up? Never really gave it much thought... but starting the engine, grabbing the voltmeter and revving it to 4K... the thing is already pretty darn hot!

-

Speaking or Mofset rectifier... any body offers a plug-and-play unit?... Or do I need to do some tinkering with a SHINDENGEN MOSFET FH020AA kit?

Since you have a voltmeter, try this again: Jumpstart the bike, and check for the voltage across the battery terminals when the engine is running. You could also check it on the powerlet socket, both numbers will match.

The stock rectifier is crap, and a series RR is a huge improvement over it. As you noticed, it gets hot because it shunts all the extra unused power. At idle, you effectively touched a 250W heater, which as you noticed isn't pleasant to the hand. The mosfet rectifiers run cooler, the series rectifiers make the alternator run cooler (and potentially saving you a 200 dollar stator in the future).

Either rectifier is a step in the right direction, with the series one being the better buy, but I feel you might be solving the wrong problem. Your alternator looks fine, and the stock RR hasn't known to die on people. There might be a short or loose contact which you could be misdiagnosing.

Silly... sent you a PM/conversation.

Had the battery on a trickle charger last night... With the bike running, I got 12.8V at the battery. No change between idle and 4000rpm.

Couldn't undo the roundish plug on the rectifier to test the output. I guess next week (when I have some free time) I'll strip down the bike and look all the connection overs.

Thanks for the help, much appreciated!

If you are seeing 12.8V, that means your battery isn't getting charged at all. That connecter is a pain to get to. You need to cut all the zip ties to gain access to it, and the stator connector slides off first and then you get to tug on the round plug. If you are ham fisted like me, you might also end up breaking one or both of the tabs that hold the connector.

Are your multimeter leads thin enough to stick under the plug to get a reading? Also, if you have the new rectifier on order, you need to chop off that plug anyway (hint!).

Your stator is dead. Your measurement from each stator wire to ground should be infinate. You measured a few ohms, which indicates all the phases are shorted to ground. You most likely will find the stator coil insulation cooked as you remove it. Those reading should be infinate with the R/R disconnected.

Erling, I thought he never got the rectifier disconnected from the stator, and that the values were with both connectors (RR -> harness and RR -> stator) in. Since the RR has two sets of + and -, I think there is always a ground in the system even with the battery removed. Either way this is strange, I would like to know the eventual outcome, mostly for curiosity's sake.

Also, are you back here for good? I suspected that the honeymoon with the wet head would end

You are correct. The two sets of wires from the stator to the R/R run in parallel. Why they used two sets in a thin gauge as compared to one thicker is beyond me. If his readings were with the R/R connected then they mean nothing, and he should do the whole test procedure as I wrote it. With the stator wires connected through the R/R it will always show a ground through the diodes. In reality the test, as I wrote it, can be done in 5 minutes. It will fully reveal what is broke, but he would have to follow it.
The honeymoon is still going well. I do not see myself going back to the F8. Have not done much to the F12 beside hanging the boxes on her, but it will come. The guys takes them self soooooooo seriously over there, and there are lots of drama, that I do not care for. The PU seems to be more relaxed, which I miss. I still feel that I can contribute as I did spend 5 years flogging one.....

Hi Erling,,,,,DITTO,,,not riding an F8,,,not even a BMW for that matter,,,but this is one of my favorite forums,,,,,,by the way,,,,I really like your creations in Carbon Fiber,,,,thank you sooo much for sharing your knowledge.
All the best,
THUMPER>>>>>>>>>>>>>>>>

This morning I found my battery dead, after recharging it, I took the voltage reading at idle with the following results:
Wire 1-2 - 10
Wire 1-3 - 10
Wire 2 -3 - 5

I should have spotted it earlier as for the past 3 weeks my heating grips were not giving the same amount of heat any more. Fortunately, BMW Motarrad UK has got the electrosport regulator & stator, which I ordered straight away.

You are aware the voltage output from the generator is AC, right? The volt meter should be set accordingly.

Cheers, Gefr. I have not changed it, after measuring the voltage on the battery. I updated the results. Would you expect the numbers to be around 20v?

ktmat - check your inbox.
mike