Second battery for my 2003 Nissan Patrol

PandJ,

what sized relay?
why not wire it off the temp sender?

You will need spike resistance for a modern car. I don't know whether the setup you want to use will cause problems. Ask your local auto sparkie.

Personally I'd get a redarc.

Hi P&J. We have a 99 Patrol, and installed the Redarc - also called a 'Smart solenoid' or 'Battery isolator'.
The unit only connects the main to the second (auxiliary) when the main is fully charged (I think to 13.5V).
You run all your accessories off the auxilliary, and never have to worry about the main being drained by the fridge/map-lights/inverter/trailer- battery or whatever.
There is a bypass wire, which we connected to a switch on the dash.
This gives you the option to connect both batteries together (eg to use the winch).
Costs around $150. Rugged and reliable - simple to DIY.
Check this forum and perhaps one of the Patrol forums (http://autos.groups.yahoo.com/group/patrol4wd/).
Most dual battery setups use them.....
Regards................Keith.

Hi Keith,
Thanks for your thoughts and idea. I really prefer to use my set up, very reliable and cheap. May have to talk to those customer service folk at nissan and try to explain something new to another office worker.
Tnx PandJ