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Discussion Starter #1
I'm having yet another stator replacement and am considering a MOSFET r/r soon. My question is how does the charging system fail?

I may be understanding wrong but I believe the stators typically fail after the r/r when it overheats or when the engine itself runs hot for a long time. I have seen people say a failed stator can also destroy a good r/r but am not sure how this happens other than perhaps very high currently from a failed stator.

I will happily spend the extra money for a shindigen if I know it won't fail for a long time. Then again, I'm up I'm the air since I've been considering selling this bike for a great deal on my friend's Triumph Bonneville.
 

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My theory begins with shorts in the junction box.

The shindengen on mine has lasted 5 years, but I did two of the wire mods. I didn't count this year, as I haven't ridden.
 

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Discussion Starter #3
So do you think doing the blue wire and two wire mods (if I'm remembering then correctly) with regular r/r would increase my stator life? Are these areas of the junction box causing excessive current to be drawn?
 

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X2 I did away with the junction box.Put in inline fuses, changed a bad ignition switch. An one step at a time I read all the info our great forum has to offer. I can drive Blanch any where now with no problems.These are great bikes once you fix them!
 

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I have no proof of this, but I think the old style R/Rs could be killed pretty quick if the ground wire or monitor wire ever got loose, since that would play havoc on their voltage regulation circuit, and they'd burn themselves up trying to meet a perceived infinite demand. I think the mosfet R/Rs are internally regulated (no monitor wire), so that's not as big an issue.

And heat, of course.
 

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So do you think doing the blue wire and two wire mods (if I'm remembering then correctly) with regular r/r would increase my stator life? Are these areas of the junction box causing excessive current to be drawn?
I think it could, possibly.

One thing I like about the Blue Wire mod, it takes 50v ac out of the junction box.

Pretty sure my bike would benefit from a separate fan relay, but I've never gotten to it.
 

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Discussion Starter #7
I have no proof of this, but I think the old style R/Rs could be killed pretty quick if the ground wire or monitor wire ever got loose, since that would play havoc on their voltage regulation circuit, and they'd burn themselves up trying to meet a perceived infinite demand. I think the mosfet R/Rs are internally regulated (no monitor wire), so that's not as big an issue.

And heat, of course.
You're definitely right about that since they rely on a good ground connection for the excess current that isn't being used. That's the biggest reason I never went to LEDs since my theory is that the r/r is the real failure point which results in the stator overheating from lack of heat dissipation.

Can a bad stator kill the r/r? That's my main concern with the MOSFET one. I don't want to spend the extra money if it's possible for it to fry from the known issues
 

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Discussion Starter #8 (Edited)
I think it could, possibly.

One thing I like about the Blue Wire mod, it takes 50v ac out of the junction box.

Pretty sure my bike would benefit from a separate fan relay, but I've never gotten to it.
Mine likely could use that too but I went with the tried and true "punch the junction box" method when mine was acting up. After two occasions of it not turning off without it, my fan now cycles properly
 

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Consider the next step up. A series type regulator. I havena't read about stator failure while using one I've read of at least 3 or 4 stator failures while using a mossfet. Other mc brands with stator problems have been using series regulators for years. I think series type wires up the same but is larger than a mossfet. Brand new they cost $150-200. I bought mine used for $50 a couple of years ago. Beware of fakes. A real one has sh775 stamped on opposite end plug ins. Good luck.
 

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Hi everyone, I just got a mosfet SH-775 put it on yesterday it replaced the older shunt type FH-020AA. It was plug and play. The two are the same size,bolt holes matched. I was able to use the same mounting bracket and as I said the SH-775 plugs right in. The SH-847 is bigger. Got the SH-775 off ebay new for $100.00. 14.38volts at 1100RPMS, 14.56volts at 3000RPMS I'm a happy pappy!!!
 

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Discussion Starter #11
So I installed the new MOSFET r/r. I took the old stator output and put the three wires to the new r/r then I have the inner terminal to battery + and outer terminal to battery -. When I turn the ignition, the positive now shorts to ground. Did I miss something or is there a ground to chase?
 

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There's no additional connections to make ... maybe double-check that 'inner' and 'outer' terminals on the R/R are actually the polarity you think they are with it disconnected from the harness.
 

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Discussion Starter #13 (Edited)
There's no additional connections to make ... maybe double-check that 'inner' and 'outer' terminals on the R/R are actually the polarity you think they are with it disconnected from the harness.
I will check when I get the chance. I think I should get a current flow only from + to - when using the diode setting on the multimeter. I suspect I just have a ground somewhere because the voltage immediately drops to zero when I turn the ignition. I think I did it with the r/r unplugged as well but can't remember off the top of my head.

The places I'm thinking to check for a ground are:
Ignition switch
Gauges and their lights
Horn
Flasher relay
Old r/r wiring
Engine cutoff switch
Lighting switch in right handlebar
Head and taillight
Turn signal lights
 

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Discussion Starter #14
I forgot to post an update. I accidentally found the main ground had a poor connection by leaving my multimeter in voltage mode. I removed it, sanded the corrosion away and it fired right up
 
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