Author Topic: Voltage regulator over-charging revisited  (Read 2275 times)

Offline robertllr

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Voltage regulator over-charging revisited
« on: August 14, 2021, 02:45:42 PM »
OK, this is how it went for me.  YMMV.

I acquired my 2013 V7 Racer, used, in 2014 with about 2,000 miles on the clock.  As far as I know, the battery and R/R were the same ones that the bike left the factory with.

I first heard about the overcharging issue on the thread started by Todd on his Guzzi Tech site it in 2016.  I tested my regulator then, and it was, indeed, over charging—15+ volts.  But I had put many thousands of miles on the bike already with no problems.  So I decided  to live with it and see what happens.

Many more miles went by (including a 3,000+ mile round trip from my home near Charlottesville, VA to NOLA) with no troubles.  Then, about a year ago, starting became iffy.  I bought a new battery—same make and model as the original (Yuasa 14 BS) and put it on the shelf.

Then, a couple of days ago—that's 8 years since the bike was built, 7 years in my ownership, 5 years since I knew of the overcharging problem, and one year after battery illness raised its head—the battery died and would not charge.  I'd been expecting this--whether or not the R/R is faulty or to blame; after all, what battery lasts 8 years? 

I'm glad I waited.  A plug and play MOSFET replacement was not available back then, and I had a feeling R & R of the R/R would be a pain.  People making up mounting plates and soldering their own wiring harness impressed, but did not move me to action.

These days, a drop-in fix is available, from several sources, so I decided to go for it.

Before I begin the description of what is involved in the R & R, (BT, there is no other place this where all the info below is available, so, you're welcome) let me point out that MG has been using that particular regulator--PN 883878--since time out of mind.  In fact, my 2007 CalVin has one and it has always performed just fine.  This site   https://www.motorcyclespareparts.eu/en/piaggio-parts/883878   lists dozens of applications for that model R/R.  Why some of them charge at over 15 v and others seem to charge at 14.4 is beyond me.  The stock, non-MOSFET R/Rs can be had for a lot less (in non-OEM guise) than the MOSFET, so if it is possible that a more recent batch of standard replacements does not over charge, replacing like for like might be viable.  I have not data on that, just conjecture.

Anyway, here is what I did on my Racer.  Trust me, not all V7's are alike.  Videos and images I've seen on the web, show configurations quite different from what I have on my bike.  As I said, YMMV.  And  I apologize for no photos.  I get into a project and I just want to get it done. 

First off, I got my part at RM Stator.  https://rmstator.com/en_us/mosfet-voltage-regulator-rectifier-for-moto-guzzi-california-vintage-1100-nevada-750-v7-special-750-2006-2014-rms020-103870   

They offer FREE two-day shipping, a warranty AND they accept returns!  Unheard of, in my experience, for electrical parts. (The usual disclaimers of advocacy inserted here...)

1. Drain the tank.  Siphon works.  But I could not get the tube in until I removed the the leather straps and the trim ring, rubber washers and  all the other stuff that surrounds the tank opening.
2. Again, models may vary but on my bike, it was IMPOSSIBLE to access the R/R plugs with the the tank slid back alone.  It's got to come off. 
3. Tank removal is well-documented;  but here goes again: 
    a. Remove seat, remove rear fixing bolt, slide tank back off mounting rubbers. 
    b. There are four (count 'em and remember to count again on installation!) disconnections that have to be made. 
    c. Lift the front of the tank and remove the big hose—no clamps, it just pushes on to a spigot on the tank. 
    d. Lift the back end of the tank and remove the smaller hose, similarly attached to a straight spigot at the back end of the tank.
    e. Uncouple the fuel pump wiring and run the engine till it dies.  Uncouple the F***ING quick connect.  Actually, mine came apart easily.  I don't know why, it just did. Sorry if yours does not; but there are six zillion and five posts about the issue.  Read 'em all if you have time! 

    4. That was the easy part (yeah, right, I know); now comes the fun part.  The two electrical connectors for the R/R are buried under the head stock—that's why the tank has to come off—you can't reach the connectors  any other way.  Every cable and bit of harness is jammed in there, and just getting to them is NOT easy. In fact I even took off the right spark plug lead from its coil to give me a bit more finger room.
    5. If you haven't taken the front tanks straps all the way off do that, too. That leather harness is also in the way.  The horns come off with it
    6. Unbolt the R/R and push it up. Tie it up or block it up—anything to get a bit of slack in the wires. You need the room. 
    7. The white coupling is a bear:  it's jammed in there with little slack to get a grip on either end.  Push down on the tab and get a smallish screwdriver in there and twist to start the separation.  Use a wider bladed screwdriver when you need to.
    8. Now the black connector it's a bit easier.  Mine had a zip tie on it to keep it together.  The connection seems secure but someone at the factory thought it needed help, so …

    The rest is easy.  Pull out the old and thread in the new.  I even put a zip tie back on the black connector.

    Then, as they  say, installation is reversal of removal.

    Hope this helps

    PS:  if you are sure your new R/R will work and are sure you are willing to trash  your old one, you can always cut the wires at the regulator--that will give you plenty of slack.  Since mine "worked" and I had no proof that the new one would work better (it does, BTW 14.4 volts at 3500 RPM) I was unwilling to drastic commitment[/list]

    Offline Kiwi_Roy

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    Re: Voltage regulator over-charging revisited
    « Reply #1 on: August 14, 2021, 11:15:18 PM »
    If you uncouple the pump electrical then try to start the engine it quickly drains the fuel pressure making it easy to uncouple the hose connection.
    Yes, I removed one of the coils to make room.
    Good write-up  :thumb:
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    Offline Old Jock

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    Re: Voltage regulator over-charging revisited
    « Reply #2 on: August 15, 2021, 03:34:56 AM »
    Thank you for going to all the trouble to document.

    It takes time and effort and although I don't have a modern(ish) Guzzi, I appreciate anybody willing to take the time and trouble to help others who may find themselves in a similar situation

    Offline Lumpy Idle

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    Re: Voltage regulator over-charging revisited
    « Reply #3 on: August 15, 2021, 11:39:27 AM »
    excellent write-up. well done.
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    Offline mr_pacman

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    Re: Voltage regulator over-charging revisited
    « Reply #4 on: August 16, 2021, 11:20:22 AM »
    I just replaced mine over the weekend with the help and guidance of Robert who started this thread.

    I followed his directions and it all went well. My old regulator was well above 15v and the new one (also purchased from the same place) was a plug and play and now is 14.5v at 3,000 rpm.

    Offline Chuck in Indiana

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    Re: Voltage regulator over-charging revisited
    « Reply #5 on: August 16, 2021, 12:44:16 PM »
    Quote
    I tested my regulator then, and it was, indeed, over charging—15+ volts. 
    I *assume* this is the same Ducati regulator that is on the big blocks? The (very common) problem on the big blocks is a simple ground issue. There needs to be a ground wire ran from the regulator case to a bolt on the engine..
    Chuck in (Elwood) Indiana/sometimes SoCal
     
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    Offline Brian UK

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    Re: Voltage regulator over-charging revisited
    « Reply #6 on: August 18, 2021, 04:35:25 AM »
    A bad connection on the voltage sensing wire, which is fed via the ignition switch will cause overcharging.
    A bad connection will add resistance which in turn will drop the volts at the regulator. The regulator will allow charging unil those volts rise to the correct value so the output volts to the battery will be higher.
    A bad earth may also cause the same problem, but will also reduce the current charging the battery as the earth connec tion is in the charging circuit as well.

    Regarding battery life a with overcharging it will depend on the type of use. Long trips will have a greater detremental effect than short ones.
    Brian.

    Offline Wayne Orwig

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    Re: Voltage regulator over-charging revisited
    « Reply #7 on: August 18, 2021, 08:21:08 AM »
    I *assume* this is the same Ducati regulator that is on the big blocks? The (very common) problem on the big blocks is a simple ground issue. There needs to be a ground wire ran from the regulator case to a bolt on the engine..

    I believe the V7 has a regulator with everything built in. So there is not ground or hot wires that sense voltage like the old Ducati setup.



    « Last Edit: August 18, 2021, 08:22:57 AM by Wayne Orwig »
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