An amp gauge measures the actual amount of electrical current flowing into or out of the battery. The amp gauge needle will move to the (+) when the generator output is recharging the battery.

Why use an ammeter and not an Ampmeter?

An ammeter (abbreviation of Ampere meter) is a measuring instrument used to measure the current in a circuit. Electric currents are measured in Amperes (A), hence the name. An ammeter usually has low resistance so that it does not cause a significant voltage drop in the circuit being measured.

How do you read a car amp gauge?

Entering the car your the ammeter should be reading 0, straight up. You may see a quick defection to the minus side if your have an interior light that comes on with opening the door. Its at 0 because you are not using any or generating any current (engine is not running).

How do I know if an ammeter is working?

Test the ammeter with the connections + from battery to + on meter and - battery to - meter and note the ammeter needle deflection. Reverse the connections on either the battery or the ammeter and you should have the same deflection the opposite way. Of course, at no current flow, the needle should read zero.

What is the principle of ammeter?

The principle of ammeter is that the resistance and inductive reactance must be very low. Ammeter has a very low impedance as the voltage drop across the ammeter should be low. The ammeter cannot be connected in parallel because of the above-mentioned reason. In a series connection, the current will be same.

What happens if an alternator is overcharging?

Alternators that overcharge will typically produce excess voltage to the battery, making the battery case swell up, become very hot and lose its electrolyte through boiling. Improperly jump-starting the vehicle can send a surge through the battery that destroys one or more cells in the battery or shorts it out.

Where should the battery gauge be at?

The gauge should read above 13 volts and below 15 volts. Readings above 15 volts or below 13 volts indicate a charging system failure that needs to be addressed immediately. Pictured above is a typical “Battery Light” that is quite common in vehicles today.