Just like most 4WD's, I'm running two batteries in the Landcruiser - the main starter battery and a deep cycle battery for powering the fridge, camp lights etc.
The two batteries are separated by a Piranha isolator switch which prevents the starter battery from being flattened overnight by the fridge ensuring it's still ready to start the engine next morning.
However if for any reason the starter battery goes flat (for example the interior light being left on) I can use a jumper cable to connect the two batteries and 'jumpstart' the car off the deep cycle battery.
But in my quest to lighten the load and reduce the gear I need to carry I've taken it to the next level and actually 'built in' the jumper cable so now jump starting the car is as simple as flicking a swicth.
Watch the video below to see how it works.