[pdora]

12 v conversion was essential in my case because I am preparing to install some high-power amateur radio equipment, and everything is designed for 12 v DC power.

As far as knowing what is going on in your electrical system, it is best to use both an ammeter and a volt meter.

The ammeter need not be very precise. Knowing exact current draw at any moment is not all that useful. The meter indicates the direction of current flow (plus / minus, charge / discharge) and the relative rate. Also, the 'wiggle' during starting demonstrates the integrity of the ignition primary system. Frequent observation of the ammeter reveals certain 'signatures' under various operational conditions, and deviations will be apparent. This can provide advance warning of impending problems.

The voltmeter should be very precise. Today, automotive digital volt meters can be had for around $20. I bought one designed to plug into a cigarette lighter and hard wired it after modifying the plastic case. Various voltage readings at rest, while cranking and while running can provide a wealth of information about the health of the battery and the alternator, the state of charge and the condition of lights and other loads.