It's one of the essentials for off-roading - make sure you have a dual-battery setup! Most people add a second battery to their vehicle when they start adding lights, big stereos, and winches. This is smart, but really, they could get the same end result by just putting in a bigger battery that had a longer reserve capacity. So why bother with two batteries and the extra wiring? The real reason to have dual batteries is in case your main starter battery dies out, and you need to jump your main off of your auxiliary battery. The biggest/only problems with dual batteries are the space occupied by the extra battery and the weight (two typical dry-cell battery will weigh over 100 pounds!)
But Odyssey had a solution for us. We remembered seeing one of its company trucks run solely on a PC680 battery - a tiny battery that looks like it came out of a motorcycle and it weighs in at only 15 pounds. Together with a PC1700 (weighing in at 60 pounds), we would only have a combined weight of 75 pounds of batteries. We would use the PC680 as the main (starter) battery, and use the PC1700 as the auxiliary battery, attaching all our accessories to the auxiliary battery.
But what about connecting the batteries together and controlling the isolation? You could just hook up both batteries' positive leads together, but then you have no isolation abilities and are really no better off than just having a bigger single battery. This is where a dual-battery kit with a relay or some other type of isolator becomes necessary. Our isolator of choice? The Power-Gate from Perfect Switch. It is the ultimate isolator and rectifier in one small package. There is little-to-no voltage drop with it, and it does not generate the heat (heat equals power loss) that other isolators/relays do. It's totally automatic so we don't have to worry about switches, and it acts as a perfect one-way electrical valve.