krj wrote in news:z7tMf.8801$eQ3.6708
@bignews4.bellsouth.net:

Fine if you are at the dock. When you are on the hook for weeks you
need
something like the Balmar Duo-Charge to charge the starting battery
when
the alternator output is trying to put that 100 amps back in the house
battery.
krj



No, then you need a switch between the two batteries marked ON-OFF to
parallel everything for charging when the engine is running. A remote
full-duty-cycle relay with a little switch up by the engine controls is
nicer. Put a pilot light on it to remind you to shut it off when the
engine isn't running.

Switch or solenoid
+ contacts +
House Batteries-----|----------| |-----------|-------Starting Battery
| |switch at engine control
| |
Alternator |--solenoid coil-|-(gnd)
DC output |---ind lite-----|

Crank engine
flip switch
Charge everything
flip switch
Shut down engine

KISS....??

We got 2 alternators, but I still have a cross-connecting switch so I can
charge everything from the one working alternator that's left. The big
house alternator failed 90 miles S of Charleston coming up from Florida.
I flipped the switch ON and noone noticed...(c; The damned fancy
multistage controller failed. The Perkins alternator pulled the load
just fine for the rest of the trip.