Ammeter or voltmeter?

Ammeter shows if the Battery is overcharging.
Ammeter in cars and trucks are measuring current to or from the battery.
Voltmeter shows the voltage at the location its connected into the system.

If your race car is getting required for electric pumps, fans, or EFI, the ammeter wiring strategy needs to be changed or at least beefed up.
If the battery is moved to the trunk, the ammeter may be kept depending on how kill switch and starter are wired in.
for example questions about battery disconnect wiring