My truck has many electrical accessories,(lights stereo, air compressor) including a winch. The battery management system gives me the option to use both batteries for starting or winching, running my accessories, or I can run everything (except winch) from the main battery. Should I run the main dowm, I have the AUX battery in reserve for starting. I've used battery isolators in the past, but they use up about 1.2vdc (give or take ) and are limited to the amount of current that they can pass.
So, I choose the dual battery management system. The dual battery system has a 3 pos. switch, Emergency, off, dual on. The Dual on is only on when the key is in the "on" position. When switched to Emergency the dual battery is switched in regardless of key position (for jump starting)
I'll look for your e-mail, and shoot you some pic's. If I can't it here, I'll let you know via this post.
Later...