Yet Another Charging Question

[Antiquar]

After installing a voltmeter to monitor charging on my V11 I have discovered a curious behavior.

 

When started cold, idle voltage (measured between battery terminals) is around 12.6V. Perfectly normal. A full charging voltage of >14V is achieved very quickly with throttle.

 

However, after the bike has been ridden at least some minutes and miles, idle voltage will drop to 12.4V. The charging system will still achieve > 14V but it takes more time (on the order of seconds, something around 10s vs 3s).

 

The fact that the charging system will output the full voltage has me somewhat content. But the voltage drop when hot confounds me. Is this a normal feature of the R/R, possibly to prevent overcharging the battery when it has been replenished?

 

Or perhaps the ECU has leaned the mixture sometime after starting and the idle is lower? I haven't noticed a perceptibly lower idle RPM on my gauge, but the Veglia gauge is not reliable anyway.

 

Curious what insight you folks might have.

 

The charging system has been the only real PITA since buying my V11, so maybe I'm being too anal.

[Camn]

There are three different wiring diagrams and two different R/R’s in use on V11. Since yours is ’00, R/R is Ducati Energia (if not changed). Is the petcock electric or manual?  If electric, the wiring is "version 1", if manual, "version 2". With this information you should get good advice from our specialist (Kiwi Roy)…

[Antiquar]

Good point Camn. 

 

My V11 is equipped with a manual petcock. And I replaced the R/R with an Enduralast direct to battery unit. I understand the behavior of this R/R might be different from the ducati version.

 

I thought perhaps I am experiencing poor venting in the tank, resulting in greater draw from the fuel pump, but I've verified that the venting is good.

 

Well, it's a Saturday morning. I'd better do some more riding as research.  

[Kiwi_Roy]

I think the charging system has a net negative loss at idle from memory the current draw is about 9 Amps with the headlight On, mine doesn't drop down to 12 but doesn't hold much more either (I have my idle set ~1000 because I like the engine braking).

The Voltage reading could also be effected by where abouts in the wiring it's attached to, downstream of the ignition switch would be a little lower.

 

 

Sent from my shoe phone!

[docc]

Interesting point about the idle value. Seems I find a lot of V11 are idled rather low (IMO) which can be compounded by inaccurate tachometers. My Sport has always been *happier* at a higher idle at which I "believe" it charges better, pumps more oil, and is more "stable." Excepting that I would rather enjoy a lumpy cam-lope idle, I don't think there is a downside to keeping the idle on the high side.

[gstallons]

The idle speed is arbritrary any way. It is strictly for foreplay while doing your walk around before taking off....

[Antiquar]

If only that were so for me. My V11 has to navigate dense traffic and countless (ok... 15) traffic lights before reaching the slab... and then some nice roads. She spends far too much time idling.

 

I overthought this one. I should just turn up the idle a couple hundred RPM. That'll probably be enough to get the idle charging to 12.6V when hot.

[Scud]

Or just get your fast idle lever adjusted - maybe with a new spring at the RH throttle body that gives you a good amount of (fore)play. Then you can turn up your idle with the lever for cold starts, stop-and-go riding, or whenever you want faster idle... and you can release it to enjoy your lumpy low-idle when you are cafe-racing.

[Kiwi_Roy]

Check your tachometer at one of the synchronous speeds under a fluorescent light, something rotating like the alternator will appear to stand still at 900, 1200, 1800 revs due to the strobe effect. 750 & 1500 for those with 50 Hz power.

If you have a frequency counter hook onto the yellow alternator wires and divide by 7

 

 

Sent from my shoe phone!

[Stick]

My Lemans is no different.  Slightly less voltage when warm.  I write it off to the alternator windings getting warmer, and possibly the RR getting warm.  When you heat wiring, the resistance goes up.  This gives you a little less performance out of a given winding and/or wiring.

[docc]

Heat related charging issues always bring me back to the 30 amp fuse thing . . .

 

http://www.v11lemans.com/forums/index.php?showtopic=12326&p=148983

[Kiwi_Roy]

Gstallons said,"It's strictly for foreplay"

 

Oh no! I'll never be able to touch the fast idle lever again.