I have a 1979 century boat with an old wiring diagram in the owners packet. It refers to a dash gauge as a "battery meter". My boat has a voltmeter. Is this the same thing ? Could this refer to an ammeter?
Quite correct. Around that era was the change-over. I suspect they moved away from ammeters for a couple of reasons. The need for high current carrying wires running up to the dash, and an ammeter can show a discharge current if the engine is just idling and some power high consumption accessories are connected to the engine loom (I really hate that idea!!) leading an operator to suspect there was a problem with the charging system when there wasn't.