"CS" wrote in message
ups.com...
I assume you are after an engine battery and house battery. Connect
both batt negatives to common ground. Connect domestic battery pos to
a on off batt switch - do not bother with a 1 2 all switch. Connect
dom bat pos to eng bat pos via a relay - Curtis/Albright - controlled
by something like a Smartbank - www.smartgauge .co.uk Connect
alternator pos to domestic batt pos or batt side of batt switch -
replace weedy std alt wiring with something more beefy. Can leave alt
neg connected to common ground. Have a suitable feed from live side
of batt switch to supply "always on" items - bilge pump, alarm etc
etc.
Smartbank will control when relay operates - charging engine battery
when engine is running and then disconnecting engine battery. Smart
bank can also be used to parallel batteries for emergency starting
using RJ45 cable and push switch.

I have a similar problem, I have one starting battery and two house
batteries. The starting battery and one house battery is located on the
center of the boat behind the engine while the second house battery is
located in a locker on the starbord side. I am replacing the house battery
located behind the engine with two six volt house batteries but because of
lack of space I will be able to put only one six volt behind the engine and
the second six volt beside the other 12 volt house battery in the starbord
locker. The questions is, what is the best and safest cabling options. The
distance between the center batteries and the starbord batteries is about
two feet.

Sterling