Re: Building a New battery system, need ALOT of help
I wouldn't bother with a voltmeter - but I would recommend a good battery monitor like the Victron BMV-600. It tells you the actual battery state, amps in or out as well as voltage. Victron BMV 600 Battery Monitor
As long as the charger is a proper 3 stage one I would leave it on if you are using the boat often. For longer periods when the boat isn't being used it can be shut off - every month or 2 it can be turned on to fully charge the batteries.
Living aboard in Victoria Harbour