Arnold Schultz wrote:
   "You need a continuous duty relay.  They are designed to be on for
long times, do not get hot, do not use much current.
. . . . . . . . . . . . 
Why did you hear the Isolator is not good?"

  Among continuous duty relays, some require constant constant actuating
coil current to stay either engaged or disengaged, depending on design.
These, when they are actuated, present a small but constant parisitic
load to the system.
  However, other spring loaded toggle type continuous duty relays only 
call
for current briefly during actuation for the act of switching.  
Certainly,
if you elect to use a relay that requires constant current for actuation,
you'd want to configure your system so that the only time the actuating 
coil
is drawing current the charging system is on.  It seems to me that this 
could
either be keyed to come on with the motor being on, or with a voltage 
safely
above the 100% full battery charge voltage level.
  The first approach would isolate the coach battery when the motor is 
off,
but automaticly charge it when the motor is on.  The second approach 
would
do that for you, but if you plugged your camper into a land based 
charger,
it would also recognize that that was an appropriate time to join the two
batteries for simultaneous charging.

  I'd also like to hear what's supposed to be bad about typical RV solid
state isolator blocks.  I happen to have one in stock that I thought I'd
install with my inverter and land line automatic charger.  I'd like to 
avoid
making a bad judgement call.
		Thankzzzzzzzzzz
		John Wakefield