Another Compufire and Possible Failure Thread

[salty_monk]

2 new RR's going down? That would be rare! I have some known good shunt ones you could try for comparison I guess....

 

[posplayr]

Could anyone with a compufire unit perform a diode test for comparison?

Nic

The compufire doesn't have a diode bridge and neither does the SF775 therefore the test doesnt apply

 

[niclpnut]

I think I finally identified the problem.

I took a fresh look this morning and reexamined the stator and the windings. I noticed one leg of the stator had what looked like a "rub" mark on the wire, just before going to the windings.

I figured it might have been touching a part of the stator cover once it was mounted. I bent it slightly further over the shoulder of the stator and away from the mounting area of the stator cover.

Reinstalled the stator and reconnected everything...

13.5v at idle, 14.4v at 2500 and 14.4V at 5000.

Happy to know that both reg/rec units therefore are not faulty and it was a simple issue that yes took time to figure out, but in the end persistence paid off.

Thank you all for your help and insight

Nic

 

[tom203]

Thanks for update. I'll wonder how you got 72 volts during AC test, but I'm glad it's fixed.

 

[JayWB]

Hey why is there not a load test?

Something simple like connect 2 or 3 leads to a 60w light bulb and measure the voltage while the bike is at xxxx rpm and it's lit up. Or measure the current. Then try the other leg combinations.

Having voltage there doesn't really mean anything.

I once had 148v ac on a 110ac line. Come to find out that at the other end the return was faulty and all that extra voltage was just induced. Kind of like what you would get with a step up transformer. It couldn't carry any current but showed lots of voltage.

There's a really easy and cheap way to do a loaded test, use 3 100 watt light bulbs. Mount them in a triangle, or Delta, and put one of your 3 phase wires at each corner. With the engine running the light bulbs will light, but not as brightly as normal because of the reduced voltage. They're also dissipating less power because of the reduced voltage, only about 60% as much as normal. This means that 100 watt bulbs are actually only dissipating about 60 watts each, for a rough total of about 180 watts total. Run the motor with only the lights connected to isolate between a stator or rectifier / regulator problem.

 

[posplayr]

There's a really easy and cheap way to do a loaded test, use 3 100 watt light bulbs. Mount them in a triangle, or Delta, and put one of your 3 phase wires at each corner. With the engine running the light bulbs will light, but not as brightly as normal because of the reduced voltage. They're also dissipating less power because of the reduced voltage, only about 60% as much as normal. This means that 100 watt bulbs are actually only dissipating about 60 watts each, for a rough total of about 180 watts total. Run the motor with only the lights connected to isolate between a stator or rectifier / regulator problem.

I guess I should not be too surprised if someone has ever already done this, but do you have a picture?

Given the arguments I was getting before about duing a dummy load test, it would be satisfying to see a dummy light buld setup.

 

[JayWB]

I built this about a year ago to troubleshoot the charging system on my GS550L. Didn't take any pictures, but it's remarkably easy to do. I took 3 ceramic ceiling mounting sockets and wired them in a triangle. That is to say, each socket has 2 connections, silver and gold. I wired them silver to gold, silver to gold and silver to gold. This results in literally a triangle of lamps. I then connected one of the three stator wires to each gold connection on the sockets and installed a 60 watt bulb in each socket. I suspect that the rating of each bulb being the same is more important than the rating itself, but 60 watts is cheap and easy to find. Note that this means an honest 60 watts, NOT a 60 watt equivalent CFL lamp.

So with this connection I fired the motor up and found a very consistent 72 volts AC across each leg. I suppose if you provide some airflow to keep from overheating and start with a well charged battery you can run it this way for quite a while, since the lamps are running at a significantly reduced power.

It certainly beats trying to make do with a no-load test, which for my money is almost useless unless you have a dead short in the stator. And the whole thing costs no more than about 10 or 15 bucks.

 

[posplayr]

I built this about a year ago to troubleshoot the charging system on my GS550L. Didn't take any pictures, but it's remarkably easy to do. I took 3 ceramic ceiling mounting sockets and wired them in a triangle. That is to say, each socket has 2 connections, silver and gold. I wired them silver to gold, silver to gold and silver to gold. This results in literally a triangle of lamps. I then connected one of the three stator wires to each gold connection on the sockets and installed a 60 watt bulb in each socket. I suspect that the rating of each bulb being the same is more important than the rating itself, but 60 watts is cheap and easy to find. Note that this means an honest 60 watts, NOT a 60 watt equivalent CFL lamp.

So with this connection I fired the motor up and found a very consistent 72 volts AC across each leg. I suppose if you provide some airflow to keep from overheating and start with a well charged battery you can run it this way for quite a while, since the lamps are running at a significantly reduced power.

It certainly beats trying to make do with a no-load test, which for my money is almost useless unless you have a dead short in the stator. And the whole thing costs no more than about 10 or 15 bucks.

I agree, it is too much trouble to Remove&Replace the stator to diagnose if you cant fault isolate between R/R and the stator. The loaded stator test is the most conclusive. Especially with the newer SERIES R/R's the old factory R/R tests just do not apply.

I wonder how much current you had through any leg. If you figure 60 watts then according to my calculations that is about 2.5 amps in each leg of the Y wound stator. With the 10 ohm power resistors I was expecting about 4.5 amps per leg.

At that power level you are pretty close to full loaded test.

After I find my dummy load testor, I'll offer it up for anybody to borrow.

 

[Guest]

Thanks for update. I'll wonder how you got 72 volts during AC test, but I'm glad it's fixed.

You wonder eh?

If any one of the legs are being shorted to ground it wont affect what your reading because the ends are open and you are measuring from one to the other and not to ground. It will however affect the regulator and give you this little snag.

So even if you shorted one leg to ground and measured from ground to either of the other two you would still get full voltage.

Lesson is: If your going to test and you get good ac voltage, Warm it up and check to ground for each one




What about the maximum current the stator can handle? How would you test it ?
Something like a normal battery load tester. It would be nice to know some numbers. Say for instance, with 240w load you will get xx amps at xx voltage and its good if the voltage is xx and not if is xx.

Building something that can load test the stator until you reach the maximum current the stator can output would be more useful than seeing if it can put out just enough current, right ?

If for instance you had some burnt coils but not enough to significantly reduce open loop voltage or current under a normal load test How would you know if you had that problem without fully load testing it.

 

[tom203]

"Lesson is: If your going to test and you get good ac voltage, Warm it up and check to ground for each one "

That was my first test- hot ohms looked good . So I kept riding out of curiosity- wondering why battery didn't die (at least 8 starts and 4 hours riding) with voltage never getting above 12.5 .