You make an excellent point on the single failure

point.  I've been trying to come up with a way to

eliminate the problem, but outside of going to 2

switches, I'm not sure how to do it. Even with 2

switches the one for the engine is still a single

failure point for the engine. 

 

I'm sure there is more than one 'right' way.  My choice was 2 batteries, two contactors, 2 'master' switches.  The engine critical bus is powered directly from both batteries, isolated by Schottky diodes.  The circuits for each set of injectors, and each set of coils are separate, as is backup for ECU and fuel pumps.  These circuits are protected by fuses.  Both masters can be off and the engine still run.

 

Your experience caused me to review my system for single point weakness. The 2 master switches have separate grounds to the panel ground bus. There is only one #12 lead from the panel ground bus back to the copper pipe (which is my main ground lead from batteries in front to engine in back).  It is bolted and soldered at the ground bus, but fastened to the copper pipe with a sheet metal screw through a loop connector.  I need to review that connection to make certain that it can not come loose or lose contact.  I will also review the other single point connections on the ground side.  I don't consider a heavy gauge wire a potential single point failure; but a connection always has to be considered suspect.

 

Sharing your experience can result in improved reliability for the rest us.  In my business as commodity trader I have a motto; "take the loss, but don't lose the lesson".  Each time there is an occurrence such as yours, we need to learn from it.

 

Best,

 

Al