You're gonna laugh (Everybody else has) but I used MARINE BATTERY SWITCHES....pop it from bank 1 to 2 regularly, and if winching, or jumping (I've jumped off Pinzgauers, Unimogs & Deuce & a Half's, Even a 20 ton Wrecker w/dead batteries) w/this setup. just switch to 'both/all'. You can run a 12k lb warn for 8-10 min. and be fine (that'll KILL STONE DEAD, most other single configuration batteries where somebody isn't sitting in the drivers seat pegging 2500rpms to keep the std alt. maxing the 90amp output, & sometimes even Then) & learned the isolator trick from 12v specialists. Starting battery, house batteries, keep 'em separate unless You need it "ALL", then go for it. A marine battery selector switch (located under hood, close to 2nd battery (saves on long copper runs....they aren't cheap these days) is Much Cheaper and just as efficient as the pricey fancy isolators. Just be sure to insolate/isolate behind the back where mounting (I used RV Roof Repair Tape, it's thicker than shower pan liner and removes any chance of 'grounding' from back side where all connections are). West Marine is probably the most expensive source, any marine surplus store or boatersland.com is probably most reasonable. I have 2 'house' batteries hooked up to a 3kw inverter in bed of a work truck & have never needed to lug a 'generator' to most work sites (that's in/on an '00 Dodge 2500 4wd w/Reading Utility Bed). Been rigging sailboats and doing construction work (as well as twisting wrenches) life long & i'm no 'whipper snapper'. I thought 'why would I spend all this money when something else I see every day will do the same thing?' I've even seen (Smarter folks than me) people do the whole setup, then POUR EPOXY in the back side & let it set 24 hrs, 'upside down' to accomplish the same 'insulating' process, then flip over & screw to the firewall. It's badazzed when done. Wish I had the truck here now (it's at shop 24mi away), or I'd shoot You pics. It's like a turbo, or better yet, Nitrus For Your 12V System! Don't 'reinvent the wheel' or pay somebody else to do it, or buy chinese crap. Somebody else already went there and did that, 100+ yrs ago! HTH?, -Mick