Amp meter question

If you just remove it without connecting another, your car will not run. It is in series with everything except for the starter motor. If you want to replace it with a volt meter, you should (a) connect the two ammeter wires together, and (b) connect the volt meter between that connection point and chassis ground. If you have standard positive ground, then the (+) of the volt meter would connect to ground and the (-) would connect to that connection point mentioned. Once done, then properly insulate that connection point so it does not touch ground because it will be "hot".
 
There are two wire from the junction box to the ammeter. Remove one from the ammeter and run it to the other post. The other wire you will connect to the voltmeter. It does not matter which wire you use for either, as long as there is an electrical connection between the two posts. This will allow the current to flow between the two posts without the ammeter.

As mentioned above, if you have a positive ground, run a ground wire from any bright shinny location to the positive terminal of the volt meter and then run the other wire that you removed from the ammeter to the negative terminal on the voltmeter. If you have a negative ground, just reverse the wires on the voltmeter.
 
In later years, instruments, with the exception of the ammeter, were connected to the ignition switch to turn them on and off. While a volt meter may not draw much current, it still may be advisable to turn it off when the vehicle is not in use.
 
rotorwrench said:
In later years, instruments, with the exception of the ammeter, were connected to the ignition switch to turn them on and off. While a volt meter may not draw much current, it still may be advisable to turn it off when the vehicle is not in use.
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That's a good point, and adds a bit of complexity to converting to the volt meter.


In my opinion, the stock ammeter would be more informative about the charging situation than a volt meter. Especially on a stock Model A. Knowing both voltage and current are helpful when troubleshooting, but I think Henry used an ammeter on purpose when he could have used a volt meter. (My opinion is usually worth what you pay for it.)
 
That complexity can be simplified if you have a battery disconnect and use it every time you turn the engine off.
 
Model A ammeters are not marked for polarity on the terminal side. It's only marked for charge and discharge on the face. The charge side of the indicator is connected to the generator since it does the charging. The battery side is the discharge side. If the wires are crossed, it won't hurt anything but it will show a discharge when charging and a charge when battery is being used for loads or when the generator is not functioning so in effect the indication is opposite what it should be. It will only work one way.

If the coil connections are per the 1929 service bulletin then the coil is on the load side, If you turn the ignition on, the ammeter will show a discharge any time the points are closed. When turning the engine over, the indication should fluctuate to the discharge side every time the points close. After it starts then the ammeter should go to the charge side given enough engine rpm. This is a way to check the ignition system on each start. A volt meter won't do that for you.
 
Lefthander1930 said:
Removing amp for Volt Meter, The two wires connecting The amp meter, can they be removed with any issues ?
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Did you actually find a volt meter that will go into amp meter location (including depth)? If not, just leave the amp meter there and install the volt meter somewhere else.

Charlie Stephens
 
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