Some of this is probably common knowledge for most of you, but coming from a single engine ski boat I learned some things that aren't obvious that I think are worth sharing.

• If you have shore power, the battery charger is tied directly to both batteries, bypassing the battery switch completely.
• The output of both alternators is tied together before the battery switch. This explains why there's only one voltmeter on the dash.
• Because both outputs are tied together, you could have one alternator dead and not know it. The only way to check is to run each engine by itself and check for proper voltage.
• The setting of the battery switch also determines which (or both) of the batteries will be charged by the alternator(s).

Always had twin engine express cruisers before, but glad you posted this. Confirms some of the things I may need to know one day.