1932 ampere meter

[LakeGuitars]

Hello!
I've converted my 32 Ford from 6V to 12V using a rebuilt 1939 generator. It will charge approximately 40ampere. I want to use the stock 32 ammeter, so first of, can I do that even though I'm running 12V? And second, how do I wire it? I've looked at some old and new wiring diagrams and they are not similar. My guess was to run one wire from the battery side of the solenoid to one side of the ammeter and then run the other side of the ammeter to "battery" on the regulator. Is that correct or am I completely wrong?

Thank you for your help!
Simon

[rotorwrench]

The 30-amp ammeter works OK on the 12-volt alternator conversions on Ford tractors so it should be OK for a car with 12-volt generator too. The ammeter doesn't care what the system voltage is so that isn't a factor. As a general rule, one terminal of the ammeter is connected to the battery source and that's usually at the starter solenoid or switch. The other terminal is connected to the buss and generator side although some intermittent circuits are fine to be connected to battery side like the horn for example.

If the charge indicator goes minus into discharge when you know the system is charging OK, the leads may have to be swapped on the ammeter to get correct polarity. Same thing if the needle goes to positive charge when you turn on the lights with the engine stopped.

[JSeery]

Which diagrams have you been looking at? The wire to the cutout would become the wire from the regulator, battery terminal. You are going to have to check the polarity on the ammeter, but I would assume it would be revised from the original. You are wanting to see current flow to and from the battery, so everything should be on one side and the battery connection on the other. No idea why they have the dome light on the battery side, but shouldn't be an issue.

[Charlie Stephens]

Originally Posted by LakeGuitars

Hello!
I've converted my 32 Ford from 6V to 12V using a rebuilt 1939 generator. It will charge approximately 40ampere. I want to use the stock 32 ammeter, so first of, can I do that even though I'm running 12V? And second, how do I wire it? I've looked at some old and new wiring diagrams and they are not similar. My guess was to run one wire from the battery side of the solenoid to one side of the ammeter and then run the other side of the ammeter to "battery" on the regulator. Is that correct or am I completely wrong?

Thank you for your help!
Simon

The ammeter will work fine on 12 volts. Your idea should work. I had the same concern when I went to 12 volts. I just ran a wire across the two terminals on the back of the ammeter. Now part of the current goes through the ammeter and part through the wire that I added.

Charlie Stephens

[Andy]

I ran a 39 gen with a 56 case for 12V. It worked great. The stock ammeter was used with no problems.

[rotorwrench]

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Originally Posted by Charlie Stephens

The ammeter will work fine on 12 volts. Your idea should work. I had the same concern when I went to 12 volts. I just ran a wire across the two terminals on the back of the ammeter. Now part of the current goes through the ammeter and part through the wire that I added.

Charlie Stephens

That would be a shunt wire. A shunt may help out the ammeter if the system ever draws more than 30-amps. The electrical engineers usually calculate the resistance of the shunt requirements and use a wire length that matches the system needs. We use a purpose made shunt on a lot of the helicopters but some still use a shunt wire. They still use ammeters but the late models are sensitive to spikes with 70 or more amp capability so they use a fuse in the circuit to protect the meter.

[LakeGuitars]

Thank you very much for your help, installed both an idiot light and the ammeter with a shunt wire and so far everything seems to work fine. Thanks again!