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Crap, I WAS in 5th gear.
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Discussion Starter #1 (Edited)
I have a problem with my new MOSFET. I have ran a ground wire and power wire in parallel with the existing harness wires, but directly to the battery, and used the stator wires from the existing harness. The R/R was put in the factory location, but does not appear to run over about 120-130F. The bullet connectors were removed from the stator and the wires were soldered.

I ran through Slim's spreadsheet twice with stator hot and cold- may do that again.

I am either losing a leg of the TPE rewind when hot, or there is a problem with the MOSFET. Another possibility is that something is going on with the stator wires in the factory harness, but I have tested the stator through the R/R harness and wiring appears to be fine. I will clip off the parallel factory +/- wires and see if that makes any difference- probably not.

Does anyone know where I can get troubleshooting info for the MOSFET?

Any ideas on how I could use a DVM with a current clamp on the stator legs? Current output of the legs may be confounded by a MOSFET problem. If the output on all three legs is the same, does that mean the MOSFET is bad?

Has anyone else put a MOSFET in the factory location? I ride 2-up sometimes and didn't like the idea of wifey's boots catching the wiring. Perhaps it's just getting too hot? Relocating is not an option right now.
 

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I had to do the same thing, installed a TPE rewound stator and a MOSFET R/R. I installed my MOSFET in the original place so far I haven't had any problem, it's been over a year.
I did not use the original battery wires at the R/R I capped them and taped them up in the harness along with the brown wire? Of course i left the original battery wires attatched at the battery. I taped into the original stator wiring because one of the stator wires is spliced with a wire going to the JB for the headlight relay.

I'm assuming the voltage at the battery is not correct when the bike is running, u didn't mention what it was. If its not, one thing you could do is make sure your batts charged up disconnect the stator wires from the bike wiring and with the bike running test the stator that way. What was the readings you were getting when u tested the first time?
 

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Mine was replaced in the stock location by the PO...but I then again, I degoated. So far, so good, many miles later. Its the belly that kills the R/R.
 

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I didn't think yours was a MOSFET Wolfie.

I am not sure if it has to do with impedence matching to the MOSFET or some other reason, but it seems that the preferred method is to tie directly to the battery and bypass the harness.

fom what I have read here and elsewhere...others who have used the stock harness have also had issues....but I am not able to explain it or grasp the reasoning for the problems.
 

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Sparky!!!
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I didn't think yours was a MOSFET Wolfie.

I am not sure if it has to do with impedence matching to the MOSFET or some other reason, but it seems that the preferred method is to tie directly to the battery and bypass the harness.

fom what I have read here and elsewhere...others who have used the stock harness have also had issues....but I am not able to explain it or grasp the reasoning for the problems.
I am wondering if the stock harness uses the wrong gauge wire along with improper routing of the positive wire.. instead of going directly to the battery, it routes through the JB... which it shouldn't do.
 

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I'm confuzzed here. Few questions. Is the headlight coming on when the bike is started? Runs off a leg of the stator. Are you testing the voltage at the battery at 3000+ rpm cold and hot? Should read about 14.2 volt. At idle all you read is battery volts(12.5). If there is a problem you may even pull the small side cover at the stator and check to make sure the wiring didn't get into the rotating drum.
 

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With the MOSFET at idle you will get more then battery voltage, chuck is correct about the head light, and the 12.5 VDC at idle if you had a OEM R/R.
 

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Here is the Mosfet FH020AA diagnostic check from Roadstercycles: I quote: Multimeter on diode check.
Positive multimeter lead to positive mosfet pin, negative multimeter to each stator pin 1 at a time, should get all zeros.
Negative multimeter lead to positive mosfet pin, positive multimeter to each stator pins 1 at a time should get all close to the same, about 100, I've seen 70 to 140 depending on ambient weather (still all good).
Now, Positive multimeter lead to negative mosfet pin, negative lead to each stator lead 1 at a time should get 435 ish all close to the same (again varies by ambient temp).
Negative multimeter to negative mosfet pin, positive multimeter to each stator pin 1 at a time, should get zeros.
If you get a zero where you should not or a number where you should not, then you possibly have a bad mosfet, odds are not good of that." End quote
 
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Giggity!
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Here is the Mosfet FH020AA diagnostic check from Roadstercycles: I quote: Multimeter on diode

~... yadda, yadda, ~

odds are not good of that." End quote
Finally, (not a hijack here) I've been trying to locate the testing for a mosfet!
Awesome on the post!

I'm linking this one!
 

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Sparky!!!
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Here is the Mosfet FH020AA diagnostic check from Roadstercycles: I quote: Multimeter on diode check.
Positive multimeter lead to positive mosfet pin, negative multimeter to each stator pin 1 at a time, should get all zeros.
Negative multimeter lead to positive mosfet pin, positive multimeter to each stator pins 1 at a time should get all close to the same, about 100, I've seen 70 to 140 depending on ambient weather (still all good).
Now, Positive multimeter lead to negative mosfet pin, negative lead to each stator lead 1 at a time should get 435 ish all close to the same (again varies by ambient temp).
Negative multimeter to negative mosfet pin, positive multimeter to each stator pin 1 at a time, should get zeros.
If you get a zero where you should not or a number where you should not, then you possibly have a bad mosfet, odds are not good of that." End quote
JM, can you link me to the diagnostics please, so I can update the TS Guide?
 

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With the MOSFET at idle you will get more then battery voltage......
My MOSFET and TPE stator has never charged at idle. Cold it will start charging at 1300 rpm but warm its mostly around 2200 rpm, then will charge to as low as 1300 rpm. But now this is on my bike. I'm sur it varies a little per bike.
 

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Sparky!!!
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Something is wrong with your upgrade then Chuck... you should be seeing right around 14.5 volts through all RPM ranges with your set up... pm me
 

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Crap, I WAS in 5th gear.
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Discussion Starter #17
My MOSFET and TPE stator has never charged at idle. Cold it will start charging at 1300 rpm but warm its mostly around 2200 rpm, then will charge to as low as 1300 rpm. But now this is on my bike. I'm sur it varies a little per bike.
This is exactly what is going on with mine. Last night, I re-wired straight to the battery using the HUGE wire included with the Roadstercycles kit, and I used primary wire from the stator leads to the R/R. All connections are soldered. Worst-case when hot with my fan and the hi-beam on is around 12.4V. Basically, running a bit better than stock, but not what I had expected. I do expect it will vary from bike to bike a little bit, as each stator will be a little different as well as peoples wiring skills.

I will check out the R/R with my Multimeter in a couple of days and report back. I can't work on it for a few days, but still able to ride.
 

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Sparky!!!
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i still think its a bad stator... when it gets hot it is shorting one leg out to ground.. I just talked two people through this over the phone over the past 3 months.
 

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Crap, I WAS in 5th gear.
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Discussion Starter #19
i still think its a bad stator... when it gets hot it is shorting one leg out to ground.. I just talked two people through this over the phone over the past 3 months.
You might be right, but unloaded, I am getting around 25V at idle and 75+ @ 4-5K and no shorts. Even if it is the stator, I'm just foing to keep riding it. I'll have my other core rewound in the meantime, and do the R/R testing tomorrow night.

I'll also pick up a cheap ammeter clamp at Harbor Freight to check the legs.
 

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Sparky!!!
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unloaded they were getting the same stator reading unloaded.. and if you unplug the tail light and headlight with the R/R plugged in you should be pulling 13.9-14.5 volts through all rpm, ranges, then drop down to 12 with the tail light plugged back in. I racked my brain for 3 months before one fo the guys finally went back and checked stator leg to ground resistance when hot. we came up with .05 ohms with engine at normal operating temps, with engine cold, the same leg to ground was getting a reading of OL. BTW all three stators had less than 2,000 miles, One was a 1 Was a rick's, one was an Electrosport, and the third was a TPE... TPE was the only one that made right as far as I know.
 
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