On Mon, 24 Jul 2006 08:30:18 GMT, ray lunder wrote:

The AmplePower people agitate for strict prohibition on this saying it
will smoke the diodes in your alternator. Is this true? What are you
supposed to do? Start the boat with the starting battery, let it run
for 10 minutes, turn the engine off and start it again with the house
batteries and charge them under way? What say all of you?

AmplePower gave you good advice. In theory the right technology will
allow you to switch batteries (make-before-break, ZapStop, etc). In
practice they should be regarded as backstops that *may* save your
alternator if you switch accidently.

Most people start their engines and run in the "BOTH" position. After
anchoring and shutting down the engine it is good practice to switch
to either "1" or "2". That should leave you with one charged battery
for restarting later on. If you have inadvertantly flattened a
battery, start the engine and warm it up on the remaining good
battery. After warming up the engine, shut it down, switch to "BOTH"
and restart. It's good practice to continue recharging the battery
that got flattened back at the dock since it is unlikely to get fully
recharged on the run back.