Thanks for the input... and the links Denny. I will have a look.

"Denny" wrote in message
oups.com...
Isolators cause votage drop and are not optimum for deep discharge
battery banks... Not recommended by me..

Ideally you will have two engine start batteries with an A-B-OFF
switch... Use the standard engine alternator and fixed voltage
regulator on the engine to maintain the start batteries... Autos use
the fixed voltage regulator and you get years of life and many
thousands of starts from your car battery... It will do the same on
your boat...
Alternatively, for two engine start batteries an isolator will work and
probably never cause you any problems and I would not criticize that
type of installation...

However for house battery banks, you want and A-B-OFF switch for the
two house banks never BOTH... You want a separate, heavy duty
alternator for charging these... You need a three charge regulator to
control the charge rate based on the battery state and the battery
temperature...... You need the heavy duty alternator for ramming a
charge to the big house batteries, a task that the standard automotive
style alternator was not designed to handle... Running a big alternator
into the start battery is a waste as it cannot accept more than 60
amps, even when discharged from a hard start...

WIth volt meters on each house bank you can switch between A and B as
you discharge the batteries, never going below 50% charge state on
either... Once A is 50% and B is getting there it is time to fire up
the engine and ram a charge into B, and once it is up switch to A..
Yes, it requires you to monitor the banks and make the decision when to
charge/switch, but it is the only way to avoid the switch being on BOTH
and having both banks exhausted...
Hers are a few web sites to give you food for thought...
http://www.powersolutions.com.au/index.html
http://www.charlesindustries.com/main/ma_alternre.htm
http://www.zena.net/htdocs/alternato..._alt.shtml#Top
http://www.e-marine-inc.com/products...nealtsgas.html

There are lots more vendors of similar products, but I leave it to you
to do the searching...

cheers ... denny
MV Levitation