Erratic Voltage - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Electrical
Where does this wire go?
Includes Electrical mods, Lights, Stator,
Rectifier, Diagrams, etc

 2Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 14 (permalink) Old 08-24-2018, 08:39 PM Thread Starter
Senior Member
 
Jason Pittenger's Avatar
 
Join Date: Apr 2018
Location: Northern Illinois (Not Chicago)
Posts: 240
iTrader: (0)
 
Garage
Erratic Voltage

I have my bike back now after my accident. I noticed while riding, the headlight brightness is fluctuating.

I had this issue before the accident too. The main ground wire had broken (pre-accident) and I just assumed that was causing the issue.

I fired it up in the garage and measured the battery voltage. I saw 13.5 at the lowest and 16.0 at the highest. I didn't notice any pattern to it. By the time it got hot enough to kick on the fan, it no longer fluctuated and remained steady at 14.

I pulled and jiggled wires but couldn't make it happen. I measured the stator leads AC (while connected) at 8.9 V.

I haven't had any low battery issues. If anything, it seems to be too high of voltage.

Thoughts?


'89 Vulcan 750 Bought 4/12/18 @ 17805.9 miles $800
Purchased stock. Wrecked once
22490.0+ miles

Completed modifications:
Removed mufflers, straight pipes out of GB
110/90 Front Tire
Pick-up coil re-gapped to .020"
Compufire 55402 r/r series regulator
USB Outlet + Voltmeter
Repainted Metallic Blue w/ new tank bages
Ear Shave (wo/ coasters) 40/140 NO shims 45MPG
MCCT conversion

Planned modifications:
Custom LED turn signals
Windshield
Highway Pegs
(Possible) ignition advance
Jason Pittenger is offline  
Sponsored Links
Advertisement
 
post #2 of 14 (permalink) Old 08-24-2018, 08:56 PM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 6,595
iTrader: (5)
   
16v is pretty hot, that will over charge the battery. Make sure the battery connections are clean and tight. 14v with the fan on isn't normal.

Probably need to test the r/r.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
Spockster is offline  
post #3 of 14 (permalink) Old 08-24-2018, 09:22 PM
Senior Member
 
kryptonianjorel's Avatar
 
Join Date: Jul 2014
Location: Washington DC
Posts: 167
iTrader: (0)
 
My headlight did that too. Replacing the stator and R/R fixed it.

and yeah, 16v shouldn't be happening. If the regulator is putting out 16v, I'd have to guess that it's busted
kryptonianjorel is offline  
 
post #4 of 14 (permalink) Old 08-25-2018, 09:35 AM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,637
iTrader: (4)
     
Garage
So, you weren't riding the bike, it was parked and idling? You didn't mention what rpms you were getting these readings from.

If your bike is sittimg and running long enough for the fan to kick on, your R/R is likely getting pretty hot too.
Voltages do vary while running, and by this I mean when the bike is moving. I'd see mine occasionally spike at 15 volts or so, but it never sat there for any length of time (perhaps a full second) and would drop to 13.8~14.5 range.

16 does seem high. I think replacing the R/R be a good move. What did it measure before you started the bike?

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/
Knifemaker is offline  
post #5 of 14 (permalink) Old 08-25-2018, 04:41 PM Thread Starter
Senior Member
 
Jason Pittenger's Avatar
 
Join Date: Apr 2018
Location: Northern Illinois (Not Chicago)
Posts: 240
iTrader: (0)
 
Garage
I didn't test battery voltage before starting. Most readings were at idle, and staying below 15. Revving it up, it would usually stay around 14-14.5, but sometimes spike to 16v. It wasn't tied to any particular rpm. Above 2k-7k it was the same.


'89 Vulcan 750 Bought 4/12/18 @ 17805.9 miles $800
Purchased stock. Wrecked once
22490.0+ miles

Completed modifications:
Removed mufflers, straight pipes out of GB
110/90 Front Tire
Pick-up coil re-gapped to .020"
Compufire 55402 r/r series regulator
USB Outlet + Voltmeter
Repainted Metallic Blue w/ new tank bages
Ear Shave (wo/ coasters) 40/140 NO shims 45MPG
MCCT conversion

Planned modifications:
Custom LED turn signals
Windshield
Highway Pegs
(Possible) ignition advance
Jason Pittenger is offline  
post #6 of 14 (permalink) Old 08-25-2018, 06:09 PM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,637
iTrader: (4)
     
Garage
I honestly wouldn't worry about it. I would however mount a digital voltmeter you can use while riding.

The brightness of the headlight varying I'd be more concerned with. The reason I asked what your voltage was before starting the bike was trying to determine how accurate your meter is.

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/
Knifemaker is offline  
post #7 of 14 (permalink) Old 08-28-2018, 02:47 PM
Senior Member
 
readparse's Avatar
 
Join Date: Oct 2016
Posts: 167
iTrader: (0)
 
Garage
Quote:
Originally Posted by Knifemaker View Post
The brightness of the headlight varying I'd be more concerned with.
I’ve been noticing this on my bike lately when riding in darkness. I went out early this morning, before sunrise, and definitely noticed some fluctuation.

I really need to get going on those full electrical tests. But the bike has been running really well lately (knock on wood), so my main point of procrastination has been replacing this front tire.

It’s less about the tire and more a matter of just not wanting to deal with taking the wheel off and putting it back on. So it’s easy to put it off by one more day. And I do that every day 🙂

I’m currently telling myself that I’m waiting for a rainy day. But we’ve had very few of those.

1986 Vulcan 750
Purchased June 2018, as a first bike.
Put 1,300 miles on it so far.
Location: Murfreesboro, TN

AGM Battery, Iridium Plugs
SeaFoam does wonders, and I'm protected by Ride-On
Back tire: Dunlop Challenger.
Front tire: Dunlop Challenger, but about to replace it with a Kenda Cruiser.
readparse is offline  
post #8 of 14 (permalink) Old 08-28-2018, 04:40 PM
Old Fart
 
Knifemaker's Avatar
 
Join Date: Jun 2004
Location: Catawissa, MO
Posts: 11,637
iTrader: (4)
     
Garage
Charging rate is effected by rpms. If you let them drop below 3000 the light may dim compared to running at 5000. Not sure if the mosfit R/R's are better for this.

Having nice clean connections helps. The stock headlight is pretty crappy anyway. Had I kept my Vulcan I would have replaced it with a unit from another bike. It's not just the bulb, it's the reflector too. (I did add driving lights which helped a lot)
https://www.flickr.com/photos/knifem...57602271287644

Nowadays I pretty much don't ride at night, so headlight brightness isn't that important.

If You Are Not Sure If I Am Joking or Not....I AM !!Photos:
http://www.flickr.com/photos/knifemaker1954/sets/

Last edited by Knifemaker; 08-28-2018 at 04:43 PM.
Knifemaker is offline  
post #9 of 14 (permalink) Old 08-28-2018, 05:24 PM
Senior Member
 
Spockster's Avatar
 
Join Date: Nov 2012
Location: WV
Posts: 6,595
iTrader: (5)
   
Always thought the headlight on mine was pretty good, enough to dodge deer at night. Definitely room for more though.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
Spockster is offline  
post #10 of 14 (permalink) Old 08-28-2018, 06:38 PM
Senior Member
 
readparse's Avatar
 
Join Date: Oct 2016
Posts: 167
iTrader: (0)
 
Garage
Quote:
Originally Posted by Knifemaker View Post
Nowadays I pretty much don't ride at night, so headlight brightness isn't that important.
Oh, I thought the concern was something bigger than the brightness of the light itself, and more about an overall electrical problem. So you're saying if I see this headlight brightness issue, then it's nothing more than a headlight brightness issue? Because it's pretty subtle. I'm just concerned that it might be indicative of some larger problem.

I do plan to replace this headlight in the long term. I like the stock look of it, and the primary purpose of motorcycle lights is to BE SEEN, which I don't think has been a big problem for me. However, when I drive either at night or in the early morning before the sun comes up, I do want to be able to SEE better.

So that's something I want to do relatively soon (meaning... this season... maybe).
OleDirtyDoc likes this.

1986 Vulcan 750
Purchased June 2018, as a first bike.
Put 1,300 miles on it so far.
Location: Murfreesboro, TN

AGM Battery, Iridium Plugs
SeaFoam does wonders, and I'm protected by Ride-On
Back tire: Dunlop Challenger.
Front tire: Dunlop Challenger, but about to replace it with a Kenda Cruiser.
readparse is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Once registered, your User Name"cannot be changed". We can make exceptions within 7 days, but after that, it is set in stone.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome