Ducati Monster Forum

Last summer (~10,000 miles ago) I lost a battery. The days before produced uneven running. It's last day it refused to start and was replaced. Happy days the rest of the year. Seemed to be charging ok. Maybe a volt less than usual...

Charged this winter.

This year just a few miles so far. Started at 12.8V. Ten days with +/- 10 daily miles, relatively slow riding (low revs).

Today it started to cough. Then it would not start. Just solenoid clicks. 11.8V. Roll started easily in second gear, but slowly died 10 seconds later. 11.2V. Roll started again, but died after two seconds. Now, not even a click from the solenoid

Got it home. Took the battery inside. Expected it to be quite dead, but measures 11.75V.


I was planning to get it going with a charged/new battery/on a car battery and measure between the yellow wires. I've been told to look for 40-50 V alternating. If yes, the R/R is the suspect.

... just a little surprised that the last minutes of riding didn't empty the battery...

At 11.8 volts an AGM battery is considered dead. Your bike wouldn't run, so it couldn't lower the voltage further.

It's been dead'er before and brought back to years of life. Just lucky?

 Nate's right. The bike was only running off the battery with no help from the charging system. When the battery is fully charged up again check the voltage at the battery when the bike is running at 3000 rpm, then you'll know. A volt less is a lot (every Volt is precious).

Good battery CPR [thumbsup] and probably a quality battery.

Bike was likely charging then. Not sure how the battery would get below 12 VDC with a functioning charging system. :-\

Oh - out in the cold with an activated alarm. The alarm will draw from the bike's battery to charge it's own back up battery.

I read Capo's charging system thread. He mentioned that city riding, at 3,000 revs, will eventually kill the battery.

I'll do the simple on-the-battery-terminals voltage check. 14 volts on ~4,000 revs?

Your bike should be charging at 3K. I've never had an issue, even with my old 2 phase system when running at 3K.

If it were me, I'd just test the stator between the yellow wires. It should climb to 70 vac pretty quickly. If it passes that test, and the maxi fuse is good, just replace the regulator.

It HAS done 220,000 km  [cheeky]

That's what I'm saying. ;D

For the yellow wires test, my meter has a V~ symbol. Is that it? With a choice of 200 and 600.... which do I select?

Select 200.  Before that, check the charging rate at the battery like koko said.  And the connection where the stator wires connect to the regulator.  Common failure, possibly cheap fix. 

To check the connectors.... running bike, battery terminals before and after connector check/wiggle/fix? Or continuity across?

Sounds like it is bad enough that a visual inspection will show burning  Separate the connector and inspect.

No visual signs. The white connector has been replaced by three bullet connectors long ago.

What's the charging voltage at the battery?

Not possible to check when engine not running. Soon.

Off the over night charge, 13V

Half an hour later, when mounted back in, 12.8V

12.05V at fast idle, roughly 2.000 revs.
12.05 at slow idle.
12.05 at 4.000 revs.

The picture show the measurement on the battery terminals, not running, after the checks.


Across yellow wires, slow idle, 25V~
Fast idle, rroughly 3.000 revs, 40+V~


Correct to think that it's EITHER the regulator or the wires from it to somewhere. I forgot to check the black and white connectors near the regulator (just beside the yellow wires on the picture)

(https://i.postimg.cc/zfMFxHYy/charge-2022-2.jpg) (https://postimg.cc/2qQW666Y)

(https://i.postimg.cc/VkKRbH7B/charge-2022.jpg) (https://postimg.cc/68GRkzxy)

Yes, check those connections.  The 40 amp fuse too!

Yeah, the battery is starved and running total loss. Can you borrow a spare used regulator? Best check all the wires and the alternator output one more time.

Nice open airbox [thumbsup].

I keep some good used regulators as spares just in case. They come up cheap.

Replace the make the beast with two backsing regulator already. [bang] [laugh]

 [laugh]

We all know that's what needs to be done.

He's already replaced the white connector andtested the alternator.

Let's end the pain...replace the R/R. :P

Tomorrow ok for you?

 [laugh]

Just one more thing to check.










No, not really ;D

Works for me. ;D

 [popcorn]
















 [laugh]

Still six hours left of today.

Maybe I'll be a good neighbour and save the start and test until tomorrow.....

 [clap]

Are you up,  Nate?

New R/R
(https://i.postimg.cc/1X0vYzjJ/20220423-142438.jpg) (https://postimg.cc/SYsLnmqM)

... at 1,500-2,000
(https://i.postimg.cc/y6Th52NQ/20220423-142516.jpg) (https://postimg.cc/WthJqWgg)

 ;D

Would I lie to you, Lars? :-*