JohnS replied:

Jinki,
I have installed a Sonneschein immobilised gel battery in the rear of my Nissan Pathfinder to address the same need. The Optima is OK as well because you must use a battery safe for vehicle interior use (these two brands are). I used a Piranha 150S electronic isolator to provide charging from the alternator and isolate from the main battery. It works just fine. Piranha installers should be able to fit the isolator, run a heavy caple to the rear and connect to the second battery through a 50A Anderson connector (for easy disconnect). If you live in Victoria, you are welcome to contact me via ExploreOz and you can inspect my installation.

Also visit forums.overlander.com.au Been heaps of dual battery discussions there.

We are all green with envy over your new 4.8l Patrol.

JohnS

Steve campbell replied:

Had an Optima deep Cycle now for 9 months. Its on a Pirahna 150 setup. Has never let me down. I'll be putting an Optima cranking battery in when it gives up the ghost.

Steve

Jeremy replied:

Optima batteries are a great battery !.......and even better are the sonishein (as per first answer-cant speel it !)
they are both a great battery for interior use and anywhere for that matter ! You pay for what you get !.......
they are both great deep cycle batteries that are great for running fridge's etc ! they also accept high charge that
modern vehicles (thats why deep cycle lead acid batteries tend to die ) and charge up and discharge well and
do not build up resistance !. Just make sure you use a voltage sensed battery management system !, piranha,
Rotronics are both good ! Delkor batteries are also a good choice but can buld up a resistance when flattened !
all the above batteries have a huge life span....up to 10 years and well over for the soneschien !
Good Luck !

bart replied:

before you buy any of these old hack batteries listed above check out lifeline batteries at www.lifelinebatteries.com. optima batteries no good for fast charging, just check the site out for all info and data you'll need.