I don't know of any kits in the US but have seen a couple Australian market ones--which actually don't work here due to battery placement. I would first start with
Slee's Battery Tray. And then look through this thread for different
dual battery set-ups.
There are many different ways to set the system up. Some will have an isolated start battery and then an auxillary battery for accessories such as fridge. Others will have a main battery for all electrical needs and then an auxillary battery that can be tapped with a push of a button in case the main battery dies.
I wanted a super reliable set-up and didn't want to spend $$$ if I didn't need to. After much research, I found many Ozzie's swore by the
Redarc Smart Start battery isolator. Not the most advanced system out there but good enough for me. The best part is that they are only around $85 shipped. It can also combine batteries with the push of a button. I have yet to install the thing though.
