Ammeter to Voltmeter...who does it?

The ammeter reads current; the voltmeter reads...volts. An ammeter just shows you how much current is drawn by the car's accessories, basically how much work is being done by the electrical system. At least a voltmeter shows you how much your alternator is putting out.

The greatest problem with an ammeter in the instrument cluster is that all of the car's current passes through it from the alternator. The connectors corrode with age, building up resistance. Resistance means heat. Heat means melted ammeter gage...or worse.