24 to 12 volt conversion

[Jason Read]

Hello, Got my 12 v starter motor all ready to do a 24 to 12 volt conversion. I live in New Zealand my 80 series is an automatic and my 4x4 use is solo and remote. I wanted to get rid of 24 volt start as I am really stuffed if I end up with a flat battery.
I would like some opinions on the new setup. I run a portable deep cycle battery in the rear via a DC to DC charger which we can take in and out for use in the huts we stay in. So don't need to have an aux battery in the front.
I am considering 2 ways to go about it.
Option 1 is just run both batteries in parallel. This gives me great capacity for winching etc and also more leeway if I leave a door open etc. Disadvantage is both batteries could still possibly run flat.
I will then carry a portable jump starter for worse case situations. Plus I have a sporting chance if any other vehicles are around.
Option 2 is to run them with a vsr between the two. I could install a momentary switch if I ever felt the need when winching etc. Advantages to this setup is ability to self start should the need ever arise. Disadvantages is no greater battery capacity and increased cost (not too bad though)
Also curious as to which setup would give greater battery longevity.
Any help would be appreciated. Cheers

 

[StarCruiser]

Have a search on here Jason, there’s many posts on this. @Chris runs the latter setup with a dedicated starter battery. You probably won’t need the jump pack as you can use your leisure battery. Better still have a solar input DCDC charger that tops up both batteries then you shouldn’t have any starting woes. As far as longevity goes, separated batteries is always best due to the tendency of a faulty battery to bring down any battery permanently connected in parallel.

 

[Lorin]

My setup is essentially the second one you propose. Provides greater redundancy in the event of a battery failing

 

[Bat21]

I have gone with option 2. If you go with option 1 you could end up with 2 flat batteries.

Gary has done a great guide here which I followed.