Voltmeter or ammeter in the headlight.

I've thought of using a oil pressure gauge there. I would think it to be more useful than what the battery is doing but then again I'm not a purist.

"I've thought of using a oil pressure gauge there"

It would need to be an electrical gauge rather than a mechanical gauge to avoid problems with the movement of the tubing but seems like a reasonable idea if an oil press gauge is deemed necessary. If I wanted an OP gauge I'd rather have it there than in the typical location on the steering head.

Bernhard said:

I’m no electrical expert but I am amazed that you got away with fitting a milliamp gauge.
It must have been quite considerable range to cope with 10 amps
Re; “all I needed to was use a length of wire as a shunt for the ammeter.”
What exactly does this mean ?

Click to expand...

In electrical terms the word 'shunt' is when you hook two electrical components in parallel. In my case with using the milliammeter the shunt just happens to be a length of wire which has a very low resistance. The longer the shunt wire (more resistance) would result in more meter deflection. Conversely, the shorter wire (less resistance) would result in less meter deflection. So it was a trial and error method to figure the length of wire needed.

Here are a few pictures of my meter mounted in my BSA. I am not real proud of the wiring and the silicon seal looks rather agricultural, but what the heck - I was only 17 years old when I did this.



Simple diagram showing how the meter is wired



One inch diameter meter bonded inside the
Lucas ammeter case



The coiled red and white wire in the foreground is the shunt for the milliammeter



Closeup view of the one inch gauge bonded with silicon into the Lucas ammeter case (Sure does look ugly but it works!)

A voltmeter will show so much more info... A) when first switched on, engine off, state of battery charge B)alternator charging as expected, nominal V at idle, rises up to expected V when RPM's go up C) different with headlight on? as expected? D) voltage goes low? kill the lights and shag for home..

If you know how your electrical system works, this V reading can tell you a lot.