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Discussion Starter #1
My ST2 will put out about 13.2V for a while after starting but then drops to the 11.1-11.5V range once it warms up.

I've done the following:
  • It has a Duracell AGM battery that is 2 years old. I had it checked at the dealer and it's still good.
  • Installed a new Regulator/Rectifier
  • Checked the alternator:
- Verified that none of the 3 yellow stator leads are grounded.
- Verified that all stator leads passed the Ohms test
- AC output at 1200 RPM: 16V/17V/17V; output at 3500 RPM: 47V/46V/47V

Do the AC outputs look OK? If so is there something else I should check?

Thanks,
Glenn
 

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follow the steps here and you should find it. while the ac voltage looks ok, you might find it has nothing on a loaded test - get the 12v rectifier and uses it between each pair of phases.
 

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Discussion Starter #3

follow the steps here and you should find it. while the ac voltage looks ok, you might find it has nothing on a loaded test - get the 12v rectifier and uses it between each pair of phases.
Thanks Belter, this is good information.
 

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Discussion Starter #4

follow the steps here and you should find it. while the ac voltage looks ok, you might find it has nothing on a loaded test - get the 12v rectifier and uses it between each pair of phases.
belter,

What 12v dc rectifier did you use for the loaded test?
 

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I've used the Ignitec single phase regulator on my Zane Laverdas. Basically the same system as the Ducati's of the era? And they are very very well priced.
 

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Discussion Starter #7
I've used the Ignitec single phase regulator on my Zane Laverdas. Basically the same system as the Ducati's of the era? And they are very very well priced.
Pardon me if this is a dumb question, but if I unplug the bikes R/R output to the battery and read the DC voltage from the R/R wouldn't that give me the same reading as the rectifier you recommend?
 

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One sore spot on the 3 phase systems is the "white" (transluscent) connector where the stator would plug to the RR. Mys 2003 ST4s, was a bit browned from heat. Connectors should not get warm or hot. I cut mine out and used wire nuts in its place. Nice and cool now. And plenty of voltage at the battery, all the time.

To check it, look for discolration. And if you'd like, run the engine, and turn on high beam, turn signals, brake, and anything additional -- like heated grips and heated gear. Then touch the connector. If it's warm or hot, in needs to be fixed.
 

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Discussion Starter #10
One sore spot on the 3 phase systems is the "white" (transluscent) connector where the stator would plug to the RR. Mys 2003 ST4s, was a bit browned from heat. Connectors should not get warm or hot. I cut mine out and used wire nuts in its place. Nice and cool now. And plenty of voltage at the battery, all the time.

To check it, look for discolration. And if you'd like, run the engine, and turn on high beam, turn signals, brake, and anything additional -- like heated grips and heated gear. Then touch the connector. If it's warm or hot, in needs to be fixed.
Thanks for the reply Stick.

That same connector on my ST2 had an internal short and melted last year. I replaced it with "wire nuts" and it worked fine.
 

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My ST2 will put out about 13.2V for a while after starting but then drops to the 11.1-11.5V range once it warms up.

I've done the following:
  • It has a Duracell AGM battery that is 2 years old. I had it checked at the dealer and it's still good.
  • Installed a new Regulator/Rectifier
  • Checked the alternator:
- Verified that none of the 3 yellow stator leads are grounded.
- Verified that all stator leads passed the Ohms test
- AC output at 1200 RPM: 16V/17V/17V; output at 3500 RPM: 47V/46V/47V

Do the AC outputs look OK? If so is there something else I should check?

Thanks,
Glenn
One thing I used to do at a shop when a bike came in with a complaint like yours, would be to take all my readings with a multimeter on a cold bike.

Then set it up to idle with a small fan blowing through the radiator until it's hot enough for the voltage reading to change as stated.

Sometimes heat will cause an expansion in some metal, causing an "open" circuit that will close once it cools off.

It could be in the stator, or in the Reg/Rect unit.

Good luck with this one...
 

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Discussion Starter #12
One thing I used to do at a shop when a bike came in with a complaint like yours, would be to take all my readings with a multimeter on a cold bike.

Then set it up to idle with a small fan blowing through the radiator until it's hot enough for the voltage reading to change as stated.

Sometimes heat will cause an expansion in some metal, causing an "open" circuit that will close once it cools off.

It could be in the stator, or in the Reg/Rect unit.

Good luck with this one...
Thanks for the advice Dukerdr
 
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