What is an Ammeter? Question

An Ameter is an electric gauge that measure electric current in “amperes”. Amperes, often shortened to “amp” is a unit of electric current. While bolts and amperes are both measures of electricity, the difference is that amps measure electric current, volts measure the pressure that’s moving electricity through a circuit.

The Model A ammeter is a center off type meter. With no current flowing through it (off position) the needle sits on zero in the center. If something is using current in your electric system the needle points to the negative side. When the generator or alternator is charging the battery, the needle points to the positive side. If the same amount of charge being produced is being used by the horn or lights, etc., the needle will set on “0”.

Henry Ford considered the ammeter as an important diagnostic tool. Here are a few ways to use it as such!

The ammeter will show a small;; discharge when the brake pedal is pushed down, indicating the brake light is working.

When the lights are on the horn is sounded, watch the ammeter. It will mirror the amount of amps being used to do these things.

When the started motor cranks the engine, the ignition breaker points open and closed, so with current flowing in the ignition coil each time the points close, they cause the needle to flutter. By watching this, you know that the ignition circuit is complete, without even opening the hood.

When you are parking your Model A, always take a final look at the ammeter after shutting the engine off but before turning off the key. If you see a discharge, you have a switch somewhere that failed to turn off and you may return to a dead battery.

These are just a few examples of ways to use this important gauge that is sitting on your dashboard, but there are lots more to discover as you learn your Model a electrical system.