Not sure how much simpler you could make it unless you started combining the currently isolated systems which inherently would add complications. Notwithstanding, the isolator, if it is a true isolator, will only allow current in one direction - toward the thruster battery during charging. You can't draw down the house bank by the demand created from the thruster.
What you should consider is trashing the isolator in favor of a relay (commonly referred to as a combiner) to obviate the inherent 0.7V loss through the isolator to the thruster battery causing constant undercharge.
Last edited by k1vsk; 08-07-2008 at 10:43 AM.