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Discussion Starter #1
Finished installing a low mile engine in my Monster 695. Fired right up and ran it up to about 165 degrees oil temp in the garage. When I shut it down I noticed the regulator and the harness from the alternator case to the reg were hotter than I expected; uncomfortably hot to the touch. Tested the dc charging voltage and it’s at the higher end at 14.5-14.6 VDC. Unplugged the 3 wire AC supply from the alternator and I’m getting a bit more than the manual spec. In the 5-6500rpm area I’m getting 88-100+ VAC. Am I maybe just seeing the effects from charging a slightly low battery from a normal Ducati charging system? Or is the AC output far enough out of spec to worry about?
 

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Discussion Starter #3
sounds normal to me. make sure the connectors are clean.
Connectors are spotless. No corrosion or filth. Just worried about the amount of heat in the wiring and the regulator. I gave the battery a good charge last night. Will rest run again later today and see if that makes a difference.
 

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Ducati shunt-style voltage regulator/rectifiers get hot— that's why they have cooling fins and why they are best mounted in a location where they experience good airflow. Left idling in a garage doesn't supply much cooling air. When they get hot enough — they fail.

991404


The wire harness from the alternator case to the regulator/rectifiers passes a very high AC current — so any resistance at the connector will create heat locally that travels down the copper wires and damage the insulation, as well as the connector itself.


991405


The in-line plastic connector is not sealed against moisture, so eventually, the connector corrodes/loosens, and along with adjacent wire insulation, overheats and fails. This is a potential failure mode for any motorcycle, not just Ducatis.

This potential failure is best addressed by eliminating the inline connector entirely by soldering the wires directly together and by moving the RR to a location on the bike with better air flow cooling, especially if the RR is inside a fairing.

991407


MOSFET-style rectifier/regulators produces less heat as less energy is lost through the switching process — so they run cooler and more efficiently. Some owners use these as a replacement.

991408


If you don’t want to eliminate the in-line connector then replace it with a more secure connection, preferably one that is sealed against moisture. Here’s a couple of examples:
1597333291452.jpeg
 

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Discussion Starter #5
Ducati shunt-style voltage regulator/rectifiers get hot— that's why they have cooling fins and why they are best mounted in a location where they experience good airflow. Left idling in a garage doesn't supply much cooling air. When they get hot enough — they fail.

View attachment 991404

The wire harness from the alternator case to the regulator/rectifiers passes a very high AC current — so any resistance at the connector will create heat locally that travels down the copper wires and damage the insulation, as well as the connector itself.


View attachment 991405

The in-line plastic connector is not sealed against moisture, so eventually, the connector corrodes/loosens, and along with adjacent wire insulation, overheats and fails. This is a potential failure mode for any motorcycle, not just Ducatis.

This potential failure is best addressed by eliminating the inline connector entirely by soldering the wires directly together and by moving the RR to a location on the bike with better air flow cooling, especially if the RR is inside a fairing.

View attachment 991407

MOSFET-style rectifier/regulators produces less heat as less energy is lost through the switching process — so they run cooler and more efficiently. Some owners use these as a replacement.

View attachment 991408

I can’t imagine that the stock location under the seat is a great spot then. I’ve heard guys eliminating the connectors. Even though both ends of mine are good and clean, once I know this baby is going back together “permanently” I think I’ll do that with a relocate to a place with more airflow. If for nothing but piece of mind. Thanks for the input.
 

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Discussion Starter #6
Finally been able to put a couple hundred miles on the bike this week. All seems to be good, but I will definitely eliminate that crappy connector over the off season, which is coming very soon.
 
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