Connecting a voltmeter - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 9 (permalink) Old 10-09-2005, 07:39 PM Thread Starter
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Connecting a voltmeter

Hi. Replaced my stock battery with a Westco this weekend. When I pulled out the tube, it was black and melted closed! Needless to say, I was sure glad I took the advice to replace it.

Now I have a voltmeter gauge to connect. I read through the posts I could find about connecting it and came to the conclusion that I want to connect it directly to the battery - rather than after the ignition.

There's a post referencing Starman's instructions but it seems his website is no longer up. I know I'll need to use a manual switch or a relay. I'd much rather use a relay - so that powering the meter is automatic.

I know very little about using a relay - exactly how it works, where to get one (radio shack?), how to connect it, etc.

I'm guessing that the relay is a switch with a control line. The positive lead from the battery would be connected through the relay. The relay would be normally open and would close when the control line is powered. The control line would be connected to the 12V positive after the ignition.

How am I doing? Assuming what I said is correct so far, would the relay still be closed (ie, meter functioning) if the control line had less than 12V (like maybe 5V)?

All clarifications and suggestions are appreciated!

Thanks, Mark
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post #2 of 9 (permalink) Old 10-11-2005, 11:38 AM Thread Starter
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Re: Connecting a voltmeter

I picked up a relay at radio shack and connected it on my kitchen table using the stock battery, my new voltmeter, wire and alligator clips. Worked great. The relay I found kicks in at 9 VDC. So I'm also going to connect a manual switch in case I ever want to check the battery and it's below the 9V minimum.

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post #3 of 9 (permalink) Old 10-11-2005, 12:11 PM Thread Starter
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Re: Connecting a voltmeter

Okay, 1 more question . . .

I was just reading a post on Yahoo that there are BK/Y (NEG) and W/BL (POS) wires in the headlight assembly that are connected to the battery through a 10A fuse.

Is using these wires equivalent to connecting the voltmeter directly to the battery? Or, should I run the wires back to the battery and insert an inline fuse in the POS wire?

Thanks! Mark
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post #4 of 9 (permalink) Old 10-11-2005, 08:30 PM
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Re: Connecting a voltmeter

You might find this write-up bt Gandalf useful

Clock/volt meter/thermometer

Device: Freeze-Alert Thermometer from Big Bike Parts (

Digital 5 Function Volt Meter
Volt meter, clock, stopwatch, lap counter and ice alert thermometer.
Measures 11/16" x 1" x 5 1/2"
Velcro tape for installation almost anywhere on any bike model.
Part number 4-239

This device includes clock (12 hour or 24 hour), stopwatch w/lap time, a volt meter with LED indicators, a beeper for low voltage, indoor-outdoor thermometer w/high-low memory and freeze (or black ice) warning. Obviously, this is designed for autos but it is small enough for bikes and combines valuable indicators like the volt reading and clock for $27.00 in a LCD readout.

I chose to wire mine up through the head light harness. This would keep the connections somewhat protected. You can wire it to anywhere you can find the needed power sources. The devise has a ribbon of three wires, black (ground), orange (switched 12v supply), and red (constant 12v supply). Remove the headlight and locate the two accessory wires. One will be black/yellow (ground) and the other blue/white (constant 12v source). Next find any switched 12v source that is only hot when the key is turned to accessories. I used the brown wire connected to the tach and gas gauge. Splice into these wires either by soldering (preferred) or crimp splicers. [I couldn't find any crimp splicers small enough for the clock's wires]. If you solder, wrap the splices with electrical tape. You should now see the LCD display light up and indicate the time/voltage/temperature. It will stay lighted constantly but only draws about .5ma.

I wanted to make a quick disconnect so I could take the clock off. The wires are small leading to the clock, about the same size as phone wires. I had some old modular phone jacks laying around so I used them. I cut the wires from the male and female jacks and severed the wire ribbon to the clock. Match the wire colors of the clock to the phone wires as closely as possible. It doesn't really matter which is which as long as you make sure you do the same at the other end. After soldering the matched wires everything worked. All that's left is to tuck away all the extra wire and place the clock in a convenient place. The wire for the outdoor temp sensor I simply let dangle.

On the 750 about the only place is on the handlebar clamp. Velcro tabs come with the device but don't really do the job. I was afraid the Velcro wouldn't hold under the vibration of the bike. You can find your own method to affix the clock to the bike, but here's what I did.

I went to a craft store and bought one of those heat shrink bags that go over gift baskets. It comes in larger rolls as well, but I didn't need that much. I cut a section of the heat shrink wrap large enough to extend about two inches past the end of the clock and would overlap itself on the back of the clock. Next I slipped a flat cable tie under and through the wrap. Tape the ends of the wrap and along the edge of the overlap. Using a hairdryer I stretched the plastic flat against the face of the clock and proceeded around the rest of the clock. The final result is a fully encapsulated instrument which keeps moisture away and still gives you access to manipulate the controls. It is somewhat difficult to change from clock to stopwatch and from Fahrenheit to Celsius and to set the clock but it can be done. I don't know if the indoor sensor (on the unit) will give an erroneous reading because it is now encased in plastic acting as a greenhouse so the outdoor setting might be more accurate.

The last step is to cut the attached cable tie to size leaving enough tie to wrap two reusable cable ties around it and the handlebar. This allows you to remove the clock when needed. As an alternative (and I might try this later), instead of a cable tie inserted along the back of the clock, something more flexible like the packing straps that hold boxes of copy paper together might be better. A nice thing about using heat shrink is you can easily cut it away and start over. I'm sure you can find a better way to mount the clock depending on your bike but the shrink wrap is an easy and cheap way to protect the instrument.

Starting the bike for the first time with everything installed I got the low voltage beeper (bike hadn't been started for a couple of weeks). It stopped after the bike idled for a minute. On the ride the clock was rock solid and monitored the voltage. Just one last word...don't spend too much time watching the clock, voltage, or temperature. Keep your eyes on the road!

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post #5 of 9 (permalink) Old 10-12-2005, 09:35 AM Thread Starter
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Re: Connecting a voltmeter

Thank you Dianna! You are a wealth of knowledge. I'll be connecting everything inside the headlamp - which will be much easier than my original thought of running the wires all the way to the battery.
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post #6 of 9 (permalink) Old 03-05-2006, 08:46 AM
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Locating brown wire

Thanks for the information about connecting the voltmeter. Everything seems clear to me except the location of the brown wire to the tach and speedo. Any suggestions?
M/F battery
relocated r/r
relocated turnsignals
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post #7 of 9 (permalink) Old 03-05-2006, 11:14 AM
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Do you have a clymer's manual? If so, there is a wiring diagram in the back of the book. I'd scan it and upload it for you, but alas, my book is several miles away right now. Perhaps someone else has a link to a diagram already uploaded? Thanks for the post Dianna, I might have to do the same.

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post #8 of 9 (permalink) Old 03-05-2006, 12:03 PM
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I do have one and as soon as I get it, I'll whack myself up side the head for not thinking of it.


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post #9 of 9 (permalink) Old 03-05-2006, 06:31 PM
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Di and Gandalf,

Thanks to your great directions, I got the voltmeter on and fired up the bike -got good readings across the board. One addition - I used that heat-shrink tubing over the wires from the voltmeter to where they entered the headlight housing. They looked too fragile to have out in the open. Tomorrow I'll work on mounting the unit using that shrink-wrat stuff. Dianna, how did you secure the unit to the handle-bars?

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