Voltmeter diameter

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RoadScholar

RoadScholar

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I am looking for a voltmeter that will fit into a headlight shell where the ammeter currently resides.

A common diameter appears to be 2, 1/16", the English ammeter is 1, 5/8". I have done a lot of digging, but the hole just gets deeper and I haven't struck pay dirt yet. I am seeking a round instrument, not a flat panel. I have mined this forum with no success, I want a good quality gauge and 'am willing to sacrifice price for fitment and quality.

Does anyone know if a round voltmeter is available that is 1, 5/8" or close enough?
 
Go to rear of line for those still looking for needle type 1 5/8" round v meter. Temporary work around would be retaining the amp gauge wired in lamp as needle will bounce that same and use color change LED in place of the engine running warning assimulator indicator. Amp gauge should be wired so battery goes in one side and alternator output in the other so only reads the difference of charge/discharge w/o whole cycle current resisting through.
 
Keep the ammeter and use a color change LED as hobot suggests. You will find the LED gives nearly as much information as a voltmeter, and the difference is not worth obsessing over. Good luck on finding a 1 5/8" VM .... I do not think any exist.

Slick
 
Way to go, franko!
I've been looking for one of these, too. Not exactly "period correct", but hey, it might fit!
 
Years and years ago, like in the 1990s, I found a 3 gauge set at an auto parts store that contained gauges that fit the ammeter hole in a Lucas headlight.

I wanted to mount the oil pressure gauge there. It fit the hole but no room for the plumbing. That was probably a good thing after all!

You might try the auto parts store.
 
gtiller said:
Koso do a cute little digital gauge that will fit in the hole https://kosonorthamerica.com/shop/motorcycle-mx/gear-volt-meter/
Click to expand...

I looked at the Kosonor offering, but it is 40mm (1.47") at it's widest point, it will drop through the 1.625 hole in the shell; it has no lip.

I looked at the Jegs offering, and it might be a possibility, but could be a sloppy fit and leak; although I never head out in the rain, I sometimes get caught by it. (as a side note: Jegs has some 1/4-20 x 3/4 stainless 12 point ARP fasteners I purchased for the rocker spindle covers---sharp.)

My intention is to keep the Norton simple and clean; I am going to go with, or have one of my friends build me, a small electronics package that will light the warning light at 13 volts or less and off above that, if the light comes on above 2500 RPM I'll know I have a charging system issuer and head for the barn.

Thanks for the replies, I appreciate your time and consideration.
 
My boat had a voltmeter that died. When I dug it out of the panel, I discovered it was an ammeter with a resistor wired into the circuit, and a custom face attached to the gauge. News to me at the time, but apparently the only difference between a voltmeter and an ammeter is the resistor and the face.
Back to the original post, it shouldn't be that hard to convert the original ammeter to a voltmeter. Maybe worth adding that the converted voltmeter would probably thrash around just as violently as the original ammeter.

Stephen Hill
 
Stephen Hill said:
My boat had a voltmeter that died. When I dug it out of the panel, I discovered it was an ammeter with a resistor wired into the circuit, and a custom face attached to the gauge. News to me at the time, but apparently the only difference between a voltmeter and an ammeter is the resistor and the face.
Back to the original post, it shouldn't be that hard to convert the original ammeter to a voltmeter. Maybe worth adding that the converted voltmeter would probably thrash around just as violently as the original ammeter.

Stephen Hill
Click to expand...

Well, the amp meter needs a shunt - a low resistance resistor that passes most of the the current. The meter movement is wired in parallel with very high resistance thus, due the appropriate Ohms law the meter will show the current.

Aircraft shunts are typically 50mv that is, a 100 amp shunt will run a 50mv meter to full scale at 100 amps. Aircraft typically have load meters calibrated in % wired to show generator load so one meter can be used for multiple applications, the shunt just has to be sized to the installed generator. With a load meter installation a voltmeter is always installed.

Automobile amp meters generally have an internal shunt since the currents involved are generally small, usually no more than 60 amps; motorcycles less, of course.
 
My ammeter had died, and was completely broken.
Preferring a voltmeter, I bought a cheap (< $2) item from eBay, and grafted it into the ammeter housing:

Voltmeter diameter
 
Gilesy said:
https://www.improvingclassicmotorcycles.com/products.htm
UK based firm which do a charge warning light that is a direct fit into warning light holes.
Click to expand...

Super thanks Gilesy, this is what I was hoping to build. I just purchased two Deluxe units, one for positive ground and one for negative ground. I think, for me, that the warning light will be less distracting then a digital or analog gauge and it will make the exterior of the Norton less busy.

Bucksfizz. Your implementation is what I was seeking initially, you do good work. I have come to appreciate what the charge warning light vendor that Gilesy pointed me to says about the information presented by their warning light product: "No news is good news".
 
rgm do an excellent low voltage warning light device which replaces the original lucas can... so there is still the functionality of a simple red light... the original ammeter was Lucas and am pretty sure you can get a volt meter from Lucas in the same size ..
 
JimNH said:
I thought you were determined to have an actual volt meter. I have the Sparkbright and it's not distracting at all. Sitting at a traffic light I will notice it change color but when riding I'm only vaguely aware that it's green.
http://www.sparkbright.co.uk/sparkright-eclipse-battery-voltage-monitor.php
Click to expand...

I was, but after almost an hour of internet mining I haven't found one that is actually made to fit the 1, 5/8" hole that the Lucas ammeter will come out of. Headlight shells with no ammeter hole are readily available, so I could make a hole, but as you know, if the hole is even 2mm off center it will bother the eye and cast a shadow over the rest of the motorcycle, the word shoddy comes to mind; good quality headlight shells don't grow on trees.

oldmikew said:
rgm do an excellent low voltage warning light device which replaces the original Lucas can... so there is still the functionality of a simple red light... the original ammeter was Lucas and am pretty sure you can get a volt meter from Lucas in the same size ..
Click to expand...

I searched high and low for a Lucas voltmeter that replaces the ammeter in the same size, I tried several Boolean search strings and found nothing. Both Lucas and Smith's offer a voltmeter with a 52mm bezel, the 1, 5/8" ammeter is more like 42mm.

I have ordered volt sensitive warning lights (one in + and one in - ground). I think I'll also order the Eclipse tomorrow, then test them and see what these old eyes like best.
 
try holden uk - they do smiths instruments and there appears to be a choice of voltmeter(s)
 
yes the smiths is 52mm -have just checked. But surely you could open the headlamp aperture to match
 
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