Charging system stator meltdowns
Currently
Checked all ground point connections Good clean & tight (previous & now)
Circuit breaker was replaced during the first repair session and the wire from 30A circuit breaker to starter post was checked then both ends good, clean, no corrosion found and retighten (previous & now). Thanks for the reminder, Ed & Max Headflow
Jbarr1: 13.4v is not acceptable if you are measuring at the battery. Something is overloading the stator. Voltage should not drop from 14 while warm and steady running.
Agreed. Thats been the brain twister all along. Solve that problem and Ill have solved the bikes charging system problem.
Thanks all so far. Keep the ideas coming
Checked all ground point connections Good clean & tight (previous & now)
Circuit breaker was replaced during the first repair session and the wire from 30A circuit breaker to starter post was checked then both ends good, clean, no corrosion found and retighten (previous & now). Thanks for the reminder, Ed & Max Headflow
Jbarr1: 13.4v is not acceptable if you are measuring at the battery. Something is overloading the stator. Voltage should not drop from 14 while warm and steady running.
Agreed. Thats been the brain twister all along. Solve that problem and Ill have solved the bikes charging system problem.
Thanks all so far. Keep the ideas coming
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,939
Likes: 8,036
From: poway
Currently
Checked all ground point connections Good clean & tight (previous & now)
Circuit breaker was replaced during the first repair session and the wire from 30A circuit breaker to starter post was checked then both ends good, clean, no corrosion found and retighten (previous & now). Thanks for the reminder, Ed & Max Headflow
Jbarr1: 13.4v is not acceptable if you are measuring at the battery. Something is overloading the stator. Voltage should not drop from 14 while warm and steady running.
Agreed. Thats been the brain twister all along. Solve that problem and Ill have solved the bikes charging system problem.
Thanks all so far. Keep the ideas coming
Checked all ground point connections Good clean & tight (previous & now)
Circuit breaker was replaced during the first repair session and the wire from 30A circuit breaker to starter post was checked then both ends good, clean, no corrosion found and retighten (previous & now). Thanks for the reminder, Ed & Max Headflow
Jbarr1: 13.4v is not acceptable if you are measuring at the battery. Something is overloading the stator. Voltage should not drop from 14 while warm and steady running.
Agreed. Thats been the brain twister all along. Solve that problem and Ill have solved the bikes charging system problem.
Thanks all so far. Keep the ideas coming
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,072
Likes: 1,006
a well designed pmg can handle 300% over load easily on a transit basis. at first, i thought 3 phase and unbalance leg (best 10% diff between legs or less) that will heat up, but that year had single phase.
with all the info above, i am leaning towards the magnets failing. a weak field will over work the system, if you had multiple fails, then i suggest replacing the rotor as well.
voltage is not the whole picture because voltage can be there with little amps and the reverse can be true also high amp draw which brings down voltage, a pmg is a fixed system and deeply intertwined.
you will get ac ripple but the battery acts like a giant capacitor and will absorb it unless too high, then the ripple has the effect of charge/discharge on the battery. matter of fact the new latest and greatest battery tester uses ac to diagnose the battery with extreme accuracy. of note here, vr ground is very important. there is a wives tale of the vr dumps excess current to ground but that is only part true, actually it only dumps when the protection circuit kicks in, but mostly the system keeps everything in check, even then, the current is AC not DC so it is WAYYYYY less.
with all the info above, i am leaning towards the magnets failing. a weak field will over work the system, if you had multiple fails, then i suggest replacing the rotor as well.
voltage is not the whole picture because voltage can be there with little amps and the reverse can be true also high amp draw which brings down voltage, a pmg is a fixed system and deeply intertwined.
you will get ac ripple but the battery acts like a giant capacitor and will absorb it unless too high, then the ripple has the effect of charge/discharge on the battery. matter of fact the new latest and greatest battery tester uses ac to diagnose the battery with extreme accuracy. of note here, vr ground is very important. there is a wives tale of the vr dumps excess current to ground but that is only part true, actually it only dumps when the protection circuit kicks in, but mostly the system keeps everything in check, even then, the current is AC not DC so it is WAYYYYY less.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,623
Likes: 6,442
From: Honah Lee
Too cool Bustert..
And no mention of AC stator output above.
That could be the reason for the DE voltage mentioned at 2000 rpm.
As usual however, with aftermarket parts with no established standards, it's extremely hard to diagnose issues. And best I can tell aftermarket is the only option.
If a permanent magnet in a stator charging system weakens, the system produces lower voltage output, leading to poor or no battery charging, reduced power, increased heat/losses (requiring more current for the same work), potential for torque fluctuations, higher vibration, and eventual system failure, as the diminished magnetic field can't induce enough current in the stator coils.
And no mention of AC stator output above.
That could be the reason for the DE voltage mentioned at 2000 rpm.
As usual however, with aftermarket parts with no established standards, it's extremely hard to diagnose issues. And best I can tell aftermarket is the only option.
If a permanent magnet in a stator charging system weakens, the system produces lower voltage output, leading to poor or no battery charging, reduced power, increased heat/losses (requiring more current for the same work), potential for torque fluctuations, higher vibration, and eventual system failure, as the diminished magnetic field can't induce enough current in the stator coils.
Last edited by Jackie Paper; Jan 10, 2026 at 10:51 AM.
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,474
Likes: 3,723
From: backwoods
There was a guy last year who bought some goofball parts of Amazon that lasted short time.
I believe he replaced rotor first time. Not sure why though
I believe he replaced rotor first time. Not sure why though
Last edited by Rounders; Jan 10, 2026 at 01:24 PM.
My customer originally brought his 2001 FLHTCUi (Magnetti Marelli) with the system not charging with only 9600 miles on the odometer. Quick check showed a "fried" (grounded) stator before teardown. Upon disassembly, we found the stator was melted, the hub nut wasn't tight and the rotor showed minor signs of contact on several magnets. Further inspection showed light contact with the stator. We checked for crankshaft run-out and found .001" with .002" endplay. We replaced the rotor & stator - checked for smooth rollover and no further contact. Reinstalled the primary drive, refilled the primary tested charging system output at the battery - 12.2v - replaced the voltage regulator and circuit breaker. Tested the charging system output - 14.2v then the voltage dropped and steadied out at 13.4v after the engine warmed up and ran for 10 minutes.
Three (3) months and 102 miles later, customer called to say that his bike quit charging while he was on a ride. We checked out his bike and found the stator had melted down again. We looked for any contact points between the rotor and stator and found none. Checked crankshaft runout and endplay again - same as previous measurements. We replaced the stator and checked output - none. We replaced the voltage regulator. Voltage check was nearly identical to the previous 14.2v at startup, settled to 13.2v while running. I asked the customer to keep an eye on the dash-mounted volt gauge while riding. He's pretty good about paying attention to his bike and to his mechanics. He loaded the bike on his enclosed trailer and down the road he went.
Forward on month and 110 miles later he called to advise he was again on a ride and noticed that the volt gauge read over 14.0v constantly. When he shut down to get something to drink the bike wouldn't restart. Back to us again. We checked the charging system output at the battery and had battery voltage only and dropping while running. After a full charge, we load tested the battery - Good, strong with no drop into the Yellow zone. We checked the stator - no shorts to ground and a steady AC output of 40v at 2500 RPM. We replaced the voltage regulator, tested the charging system output at initial 14.2v and 13.4v warm running. Again, good-to-go. Trailered the bike home.
Got a call from him early Monday that he was on another ride last week and his bike wouldn't start after a rest stop. He noticed the voltage had been near 14.0v while riding, but when he turned on his ignition switch, the volt gauge read only around 10.0v. He had gotten the bike home and put it up on a trickle charger. He mentioned that the charger hit a max of 10.2v, but the bike started. He trailered to our shop. We charged and tested the battery - again passed the load test. Started the bike and checked the charging system output with a volt meter - battery voltage 12.4v and dropping as we revved the engine up to 2000 RPM. His volt gauge showed a little over 10.0v, however. Check stator and found it had again shorted out. Only 120 mile since the last repairs.
The original replacement parts were from Drag, the subsequent replacement parts we from V-Twin and Mid-USA.
Anyone ever run into this before? If so, we're open to any and all suggestions. Thanks
Three (3) months and 102 miles later, customer called to say that his bike quit charging while he was on a ride. We checked out his bike and found the stator had melted down again. We looked for any contact points between the rotor and stator and found none. Checked crankshaft runout and endplay again - same as previous measurements. We replaced the stator and checked output - none. We replaced the voltage regulator. Voltage check was nearly identical to the previous 14.2v at startup, settled to 13.2v while running. I asked the customer to keep an eye on the dash-mounted volt gauge while riding. He's pretty good about paying attention to his bike and to his mechanics. He loaded the bike on his enclosed trailer and down the road he went.
Forward on month and 110 miles later he called to advise he was again on a ride and noticed that the volt gauge read over 14.0v constantly. When he shut down to get something to drink the bike wouldn't restart. Back to us again. We checked the charging system output at the battery and had battery voltage only and dropping while running. After a full charge, we load tested the battery - Good, strong with no drop into the Yellow zone. We checked the stator - no shorts to ground and a steady AC output of 40v at 2500 RPM. We replaced the voltage regulator, tested the charging system output at initial 14.2v and 13.4v warm running. Again, good-to-go. Trailered the bike home.
Got a call from him early Monday that he was on another ride last week and his bike wouldn't start after a rest stop. He noticed the voltage had been near 14.0v while riding, but when he turned on his ignition switch, the volt gauge read only around 10.0v. He had gotten the bike home and put it up on a trickle charger. He mentioned that the charger hit a max of 10.2v, but the bike started. He trailered to our shop. We charged and tested the battery - again passed the load test. Started the bike and checked the charging system output with a volt meter - battery voltage 12.4v and dropping as we revved the engine up to 2000 RPM. His volt gauge showed a little over 10.0v, however. Check stator and found it had again shorted out. Only 120 mile since the last repairs.
The original replacement parts were from Drag, the subsequent replacement parts we from V-Twin and Mid-USA.
Anyone ever run into this before? If so, we're open to any and all suggestions. Thanks
1) Use cycle Electric or OEM - not stuff by the Ch Ina company
2) Check the smaller wire that goes from the starter positive to the circuit breaker. Many times they will be corroded in the insulation (black copper wire at the starter side going back into the insulation is common to see on them this old). If the wire is bad replace it as it is used in the circuit for reference for charging. When corroded it will overcharge as it's got high resistance under load and the VR thinks it need to step it up.
3) Compare voltage at battery to reading on gauge so your customer has a known reading. First measure at the battery, then measure at the gauge connector. This will tell you if there is a voltage drop that needs to be addressed in the harness. Then set the gauge to read what the voltage is at it's connector (not the battery). This is done with a tiny flat screwdriver through the little hole in the gauge.
2) Check the smaller wire that goes from the starter positive to the circuit breaker. Many times they will be corroded in the insulation (black copper wire at the starter side going back into the insulation is common to see on them this old). If the wire is bad replace it as it is used in the circuit for reference for charging. When corroded it will overcharge as it's got high resistance under load and the VR thinks it need to step it up.
3) Compare voltage at battery to reading on gauge so your customer has a known reading. First measure at the battery, then measure at the gauge connector. This will tell you if there is a voltage drop that needs to be addressed in the harness. Then set the gauge to read what the voltage is at it's connector (not the battery). This is done with a tiny flat screwdriver through the little hole in the gauge.
Customer states gauge is reading 14V which tells me it could be 16+V at the battery, This is why I said to verify the actual voltage at the gauge connecter to determine if you have voltage drops you need to address in the harness and to adjust the gauge to be accurate with the connector it hooks to. If you know the delta between the gauge and the battery, you have a much more accurate understanding of what's going on.
You describe a constantly melted stator. the original one is not surprising as the 2000 stators were so bad that H-D used the remaining stock on carbureted bikes as the EFI bikes drew too much juice. I know this first hand. Then some possibly questionable parts that also failed.
You state you have no hard contact from the rotor to the stator.
It really appears from the information given that is left is an overcharge situation or every part you bought has been sub-par. Unless this thing has some crazy audio system or other aftermarket accessories you are not listing, all I can tell you is that if this happens again I would replace the wire from the starter to the circuit breaker and not just look at it and say it looks ok. I say this because from your response it reads like you may have mainly looked at the eyelets. At this point I would replace it anyway as it's 25 years old and I have had a ticket to this movie on many occasions. It is integral to the charging system as it is the reference from the battery to the voltage regulator. At a minimum see if you can look under the insulation a little - especially on the starter side.
An AGM battery will get dried out from overcharging and make a few starts then just be weak to dead. It can appear to take a charge, then repeat the cycle. Be absolutely certain the battery is not damaged at this juncture.
Last edited by Ed Ramberger; Jan 10, 2026 at 08:54 PM.
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Ed, Thanks for the pointers, so here's an update. We checked the function of the dash volt gauge and found it to be accurate, matching a DVOM reading using an external 12v battery source. We have also checked for excessive resistance in the harness feeding the dash volt gauge and have "0" resistance in the circuit. We also checked for a good ground circuit. All wires under the front fairing were OEM and we checked for any harness that might come into contact with the fairing mount brackets and the audio system is 2001 OEM. We've replaced both the positive battery cable and the cable to the circuit breaker. We've checked and cleaned the ground cable connection at the inner primary and the gang ground connections at the frame. We haven't found anything out of the ordinary. I seriously doubt that we'd have a run of "bad" replacement parts, considering that the customer's OEM stator was melted down with the subsequent stators following suite. Is there anything else that you can think of before we replace the stator and possibly the voltage regulator for (hopefully) the final attempt? Thanks for the good advise so far.
Road Master
Joined: Oct 2019
Posts: 932
Likes: 593
From: Connecticut
Ed, Thanks for the pointers, so here's an update. We checked the function of the dash volt gauge and found it to be accurate, matching a DVOM reading using an external 12v battery source. We have also checked for excessive resistance in the harness feeding the dash volt gauge and have "0" resistance in the circuit. We also checked for a good ground circuit. All wires under the front fairing were OEM and we checked for any harness that might come into contact with the fairing mount brackets and the audio system is 2001 OEM. We've replaced both the positive battery cable and the cable to the circuit breaker. We've checked and cleaned the ground cable connection at the inner primary and the gang ground connections at the frame. We haven't found anything out of the ordinary. I seriously doubt that we'd have a run of "bad" replacement parts, considering that the customer's OEM stator was melted down with the subsequent stators following suite. Is there anything else that you can think of before we replace the stator and possibly the voltage regulator for (hopefully) the final attempt? Thanks for the good advise so far.