Integrating a tiny voltmeter in the dash

[Dr_Jakob]

I went with this bigger one,



it makes my Futura look like a spaceship... Conrad.de supplies them

[DanRomani]

Hmmm... Well mine reads about 12.4 - 12.8 most of the time. Occasionally it dips to 11. As far as I'm aware, the wiring mod has been done and the ignition coils replaced. Maybe my voltimeter isn't wired directly to the battery?

[RAS]

Hmmm... Well mine reads about 12.4 - 12.8 most of the time. Occasionally it dips to 11. As far as I'm aware, the wiring mod has been done and the ignition coils replaced. Maybe my voltimeter isn't wired directly to the battery?

Is that what yours reads when the motor is running? If so, you need to put a voltmeter right on the battery to make sure that's not your actual charge voltage. If, at the battery, yer reading 14-ish, then you need to find out how that meter was wired and whether or not you have wiring issues between the battery and forward electrics. If it reads the same at the battery, then you have a charge system issue beyond the wiring mod.

[deefred]

So I drove for the first time today and now I see that there is a quite huge voltage drop to the instrument panel.
On idle with lights ON,fans ON and brake light ON the voltage went down to 11.5 volts.
I´m sure the battery voltage was not below 13.5 volts but will have to confirm that later.

One day I would like to correct this drop.

[RAS]

So I drove for the first time today and now I see that there is a quite huge voltage drop to the instrument panel.
On idle with lights ON,fans ON and brake light ON the voltage went down to 11.5 volts.
I´m sure the battery voltage was not below 13.5 volts but will have to confirm that later.

One day I would like to correct this drop.

Where did you take the feed from? When my meter was hooked up across the parking lamp in the headlight, between the drop across those filaments, and drop in the wiring from the battery forward, I'd routinely see a pretty big volt drop. Then combined with some error in the LED thingy itself, it would be closer to 1.5-2V from actual charge at the battery.

Got tired of seeing too many variables and now have mine wired thru a relay from the battery, fired from that same park light circuit.

At idle with the fans and brake lights/headlights on, I think my battery voltage will drop below 13V, but not by much.

[DanRomani]

The guy who sold it to me said as long as it was above 12v that was fine. I think he did mention how he'd wired it in but I can't remember. Obviously, he was selling it to me, so he may have fibbed but, on the other hand, the sale was through eBay and he'd already been paid, so no reason to lie...

I'll have to take it to an auto-electrician because I'm no good with any of this magic spaghetti stuff.

[RAS]

Dunno about where you are, but cheap digital volt/ohmeters can be had for $10 these days easily here. You need to have one like http://www.harborfreight.com/7-funct...ter-98025.html Not the greatest quality or accuracy, but it will save yer butt.

No magic involved and easy to use.

These batteries when fully charged are not 12V but more like 13.5V. When happy, with nothing on, they will read 12.8V. So, in order to keep up with the demand of bike's systems and keep the battery, starter, and starter solenoid happy, you really need to see 14 - 14.4V at the battery with the motor spinning at 4k RPM. Testing with that meter in the pict is as simple as setting the range to 20DCV and connecting the red lead to the pos battery terminal and the black to the ground. If you get 'em swapped, the meter will just read a negative number - no foul, no harm.

[deefred]

Where did you take the feed from? When my meter was hooked up across the parking lamp in the headlight, between the drop across those filaments, and drop in the wiring from the battery forward, I'd routinely see a pretty big volt drop. Then combined with some error in the LED thingy itself, it would be closer to 1.5-2V from actual charge at the battery.

Got tired of seeing too many variables and now have mine wired thru a relay from the battery, fired from that same park light circuit.

At idle with the fans and brake lights/headlights on, I think my battery voltage will drop below 13V, but not by much.

The positive is soldered to pin 12 of the panel which is supply and the negative soldered to the negative side of the cap as it was accesible from the underside of the board.

[RAS]

Did you ever do a side by side with your Fluke and that little meter hooked up direct to the battery? The real question is how accurate/linear is that little meter? My Kuryakin is probably 1V pessimistic.

Assuming you have 14+ V at idle, from your original pict, it looks like your seeing at least a 0.3V drop at the dash. With all that same power draw, take a read from the forward fuse that controls the dash. That'll tell you if the little meter is reading true or not. Would not surprise me that the small gauge wiring harness just can't keep up with the current draw of lights/fans etc,and you're seeing a big voltage drop from the battery forward.

At 4k running it'll go back to normal. So not a problem as long as you don't dwell on it.

And I dwelled on it. I hated seeing those big drops when mine was looking across the tail light/parking light circuit. I was neurotically trying to find yet another 2 tenths somewhere by cleaning/soldering. Straight to the battery might be less info in the long run, but a lot less stressful. And sure easier to set up.

Having it in the dash digital is sure sweet though.

[deefred]

The dash voltmeter itself is within 0.2 V over the normal range.
For sure all the connectors, swiches and thin wires are causing the voltage drop between battery and panel.
It does not bother me so much as I know that with just lights on the difference is a steady 0.6 volts lower.
I usually see a steady 13.7 volts on the dash now.
The battery bug was fluctuating much more for some reason.

[RAS]

When I 1st got the Futura, I remarked to a friend that he cooling system must be awesome cause the fans never seem to run. Well, that was wrong of course. The fans come on all the time in summer traffic. But compared to the noise my K11's fan made, these fans are very quiet. At idle and brake lights on (headlights are always on here of course) , all I have to do is to look at the meter to know when the fans are running. Bothered me the 1st few rides - it's all part of the normal now.

[Motech]

So I drove for the first time today and now I see that there is a quite huge voltage drop to the instrument panel.
On idle with lights ON,fans ON and brake light ON the voltage went down to 11.5 volts.
I´m sure the battery voltage was not below 13.5 volts but will have to confirm that later.

One day I would like to correct this drop.

I originally had mine powered by parking lamp, but big volt drop was discouraging. I found that ignition power into high-beam relay gave me least drop from battery up there under dash--.2 volt consistent throughout ranges--so that's where I rewired mine. Never faltered after that.

Nice job on your display mod D, I am impressed.

[zawalis]

I have a Bel RX-65 radar detector installed and it has the option of displaying digital voltage when idle. Works great. With mods, I see 14.0v normally.

[ericrayl]

A little more data on this subject and the regulator rectifier subject. I have the cheap voltmeter pictured wired to the Green/Orange wire that is on the switched side of the ignition switch. It's available on e-bay for $7.50 USD shipped. It's accurate as compared to my Fluke, and other than being a bit hard to read in direct sunlight I'm happy with it. Not near as cool as Deefred's install.

My wiring is totally stock with the exception of the path from regulator to battery, which has extra wires and is connected per the picture below. Regulator is a 6 month old bikepaintr unit.

Here are some readings in format (dash voltmeter/battery)

At idle, low beam on, fan off ....13.9/14.25 ....difference=0.3
At idle, low beam on, fan on ....13.3/14.06 ....difference=0.7
At idle, high beam on, fan off ....13.9/14.24 ....difference=0.3
At idle, high beam on, fan on ....13.1/13.8 ....difference=0.7
4000 rpm, low beam on, fan on ....13.3/14.08 ....difference=0.7
4000 rpm, high beam on, fan on ....13.3/14.02 ....difference=0.7

With both fan and high beams the regulator is starting to be taxed at idle. The fans drag down the voltage quite a bit just as RAS already commented.

[deefred]

If you add also the brake light (2x21 watts) on top of the other loads you will see a huge drop.