Parts:
• 2 - DieHard Platinum Marine Battery - 34M
• 1 – Battery Case
• 1 – 12v, 200 amp continuous duty solenoid
• 1 - 200 Amp 12v DC Fuse Breaker (For Fuse Panel)
• 1 – Fuse Block panel
• 4 ga Wire

Battery 1 (Engine Bay) will be the main battery with all factory components as well as extra accessories like lights, fridge and inventor will run off of when engine is off. Battery 2 (Rear storage compartment in battery case) will be the backup battery which will be isolated when engine is off with the solenoid. To me, it does make sense to use Battery 2 as the accessory battery when the factory components use the main battery when the engine is off. I like to listen to the radio as well as leave doors open when I’m out in remote areas. The solenoid will engage when the key is turned to either the Acc or On position. At that time, the 2 batteries will be linked and charged when engine is running.

 

I have been wanting to do this same thing for a while now. Can you take some pictures along the way for us?

 

They fit nicely up front if you want to save some money on cable: http://www.aedofab.com/archives/19
If you plan to put one in the rear compartment, i would recommend heavier cable than a #4. Most dual battery setups are installed for heavy winching so having short runs of heavy cable are the best setup.

If your only concern is not getting stranded unable to turn over the engine, a high quality booster pack is a great option. Just don't forget to charge it.

 

I had thought about a rear interior mounted extra/accessory battery, but my concerns were:

1) Voltage drop in long runs of cable
2) Cost for heavy enough cable to make the cable runs to the rear
3) Knowing how heavy a cable would be heavy enough ???
3) Battery in the passenger compartment (gases/explosion, I guess if you go with the AGM battery this may not be an issue)

 

AGM off-gas as well... but it's not a huge deal to put the battery in a box and vent it outside.

Why the solenoid? why not a simple battery isolator? the RV world has been using those things for decades. Best part about the isolator - you can run a deep cycle for your gear (a battery you can run flat), and your auto battery for your car.... the deep cycle battery tends to store more current.

In short (oh yeah, I do puns and I'm not ashamed), exactly what I've done on 2, soon to be 4, vehicles including a LR D2.

 

I have a similar front and rear mount set up in one of the work turds. started with 4ga had to go to 2ga....and not enough. I have very unfavorable voltage drops and have had drain issues with no explanation. I still deal with it, in this configuration. I will not do it again. but good luck to you. people do it all the time. I find it more desirable to make several long home runs and leave the batteries under the bonnet.

 

in the days of old we would use welding cable

 

The only issue with isolators is that there can be a voltage drop across them that will lead to your second battery not getting fully charged. Make sure you check the specs on the isolator. Typically, the technology that makes for a small voltage drop also makes for a high price.

 

I going to end up running a 1 GA to the rear. The only problem I'm having is seeing if two Die Hard Platinum Marines will fit in the battery area. Guess I find out when I get the other battery. If so, I will leave the 4 GA to the rear for accessories.

 

What's the maximum load on the battery in the rear? I haven't been able to figure it out from your posts.
Looks like it might be 100A or so.