Something is drawing a lot of current.
With everything connected as you think it should be, put a multimeter where the battery earth lead should be, between the battery and frame. Set the meter to the 10A scale DC.
Now run the bike to see what current is being drawn from or fed to the battery.
The alternator should easily cope with any normal load, and theoretically should supply about 10 amps.
An analogue meter would be best, but you should be able to get an idea if you have a digital meter.
DC Voltage Drops While Running
Moderator: ajleone
-
- Posts: 180
- Joined: Sat Jul 27, 2019 5:16 pm
- Location: Glos UK
Re: DC Voltage Drops While Running
Cheers
Max
Max
-
- Posts: 261
- Joined: Thu Aug 25, 2011 4:31 pm
- Location: Massachusetts
Re: DC Voltage Drops While Running
Ok, finally got back to this project. As Bill said, Tolstoy Epic
This electrical diagram is my new set up:
The previous battery wouldn't hold a charge after just a few months, so I bought another brand new battery and added the fuses in hopes of avoiding another catastrophe.
With the bike running there was 2.5-4.0 amps flowing through the ammeter:
I measured 7.32V at the battery while running. Initially I was excited to have so much voltage to charge the battery, but then I noticed the battery was leaking out the overflow tube onto the ground:
Not sure how I went from too little voltage to too much voltage.
Thoughts?
This electrical diagram is my new set up:
The previous battery wouldn't hold a charge after just a few months, so I bought another brand new battery and added the fuses in hopes of avoiding another catastrophe.
With the bike running there was 2.5-4.0 amps flowing through the ammeter:
I measured 7.32V at the battery while running. Initially I was excited to have so much voltage to charge the battery, but then I noticed the battery was leaking out the overflow tube onto the ground:
Not sure how I went from too little voltage to too much voltage.
Thoughts?
You do not have the required permissions to view the files attached to this post.
-
- Posts: 1469
- Joined: Fri Dec 24, 2010 11:29 am
Re: DC Voltage Drops While Running
I don't think 7.32V at the battery with the bike running is too much.
With the bike engine not running, the battery voltage will be less than that.
With the bike engine not running, the battery voltage will be less than that.
-
- Posts: 93
- Joined: Mon Jul 17, 2023 8:36 pm
- Location: Virginia, USA
Re: DC Voltage Drops While Running
7.32 is perfect. X 4 amps = 29 watts. That's no a lot but enough to run a bike with a 10+ watt led headlight. That's pretty good for an original stator
I just installed a Electrex stator/ flywheel and RR. I am getting 7.5v at the battery.
Your battery shouldn't be boiling over like that. Have you tried an SLA battery?
I just installed a Electrex stator/ flywheel and RR. I am getting 7.5v at the battery.
Your battery shouldn't be boiling over like that. Have you tried an SLA battery?
Last edited by mrkprsn on Sun Nov 05, 2023 8:54 pm, edited 1 time in total.
-
- Posts: 261
- Joined: Thu Aug 25, 2011 4:31 pm
- Location: Massachusetts
Re: DC Voltage Drops While Running
I do have a 6V SLA battery and by chance I measured its voltage today after sitting for weeks without a charge and it came in at 6.4V. Maybe it is serviceable 
I need to pray for some warm weather before winter really sets in so I can go for a long ride and test it out!
Will report back!

I need to pray for some warm weather before winter really sets in so I can go for a long ride and test it out!
Will report back!
-
- Posts: 180
- Joined: Sat Jul 27, 2019 5:16 pm
- Location: Glos UK
Re: DC Voltage Drops While Running
Your charging system looks like it's working well. I'd be happy with that.
Bear in mind that you are measuring regulator output, so only some of that is going to the battery, the rest is powering the ignition coil.
Has the battery been overfilled by any chance?
Bear in mind that you are measuring regulator output, so only some of that is going to the battery, the rest is powering the ignition coil.
Has the battery been overfilled by any chance?
Cheers
Max
Max
-
- Posts: 93
- Joined: Mon Jul 17, 2023 8:36 pm
- Location: Virginia, USA
Re: DC Voltage Drops While Running
delete
Last edited by mrkprsn on Mon Nov 06, 2023 4:16 am, edited 2 times in total.
-
- Posts: 245
- Joined: Sat Jun 01, 2013 4:57 pm
- Location: Paradise
Re: DC Voltage Drops While Running
Have you checked the magnetism of the flywheel? (Sorry, I haven't read all the posts I this thread.)
I knew the gentleman who got many of the tools from Berliner in the U.S. when they went belly up. Among them was a flux meter, I believe it's called, with which he could measure the magnets in the flywheel. My Mach one's FW was weak and he charged it for me, as he also had the charging machine.
This was quite a few years ago, and what became of him and his stash of Ducati stuff I don't know.
I would guess that most of the NC bikes have weak magnets after so many years.
I knew the gentleman who got many of the tools from Berliner in the U.S. when they went belly up. Among them was a flux meter, I believe it's called, with which he could measure the magnets in the flywheel. My Mach one's FW was weak and he charged it for me, as he also had the charging machine.
This was quite a few years ago, and what became of him and his stash of Ducati stuff I don't know.
I would guess that most of the NC bikes have weak magnets after so many years.
Put a Mikuni on it!
-
- Posts: 575
- Joined: Sun Sep 19, 2010 10:30 pm
- Location: Wales UK
- Contact:
Re: DC Voltage Drops While Running
Not read the whole of this topic, but have you tried disconnecting the brown wire from the electrex reg/rec. I only mention this as I'm not convinced the narrow and widecase models are the same regarding the "charging light" and electrex don't discriminate. It would be worth disconnecting it to see if it affects your symptoms. I've never used the brown wire in conjunction with an original wiring system and I don't think Electrex has reviewed all the original systems. I think the reg/reg was originally specified with a widecase model in mind.
Just a thought.
Nigel
Just a thought.
Nigel
-
- Posts: 93
- Joined: Mon Jul 17, 2023 8:36 pm
- Location: Virginia, USA
Re: DC Voltage Drops While Running
So what exactly did you do to the stator to get it to raise it's voltage out put so much?
Return to “Ducati Singles Main Discussions (& How to Join)”
Who is online
Users browsing this forum: No registered users and 45 guests