I read in a post not to long ago about using continous duty solenoids in place of battery isolators. My question is where to pick up the trigger voltage for the solenoids when the engine is running?The only thing that comes to mind is the electric fuel pump which stays on only when the engine is running.(10 sec. delay when it is not)Any thoughts?

 

It is my understanding that the idea behind a isolator is that the batteries cannot "see" each other. I also understand that the use of a solenoid in place of isolator is a better idea because is is no voltage drop. Therefore if I understand correctly by I would only want the soleniods activated when the vehicle was running, if I used the ignition switch, it would allow the bateries to read from each other when the key was in the on position, even if the engine was not running (alternator not charging).

Am I to far out in left field or what?

 

True, but would this not allow the solenoid to be energized with the engine off, thus defeating the purpose of the solenoid in the first place?