Danman replied:

I had the same situation and installed a 68amp Thumper that came with the charging regulator and relay(available from the 12Volt shops), battery from Sth Aus.
This set up works a treat and it's a dry cell unit dosent' have to be boxed or protected it can be left in the back of the vehicle,when camping or as I have done fitted in the front boot of the caravan with electric charger.
Can be then used as emergency start my D4D plus a number of other uses.
Charging from car is via 6mm cables, the local 12v point not good enough
The cost was around $600. but should last around 7years, weight is around 17Kg a bit heavy but in camp keeps my fridge going 4 days.
Cheers
Danman Vic.

Member - Peter R (QLD) replied:

I am waiting for delivery of a Prado and wanted to fit a second battery (AGM) in back of vehicle but not sure of position , or method, of doing this.

Will follow this thread with interest .
Have you had any ideas re the positioning and method?

Pedro

Member - Olcoolone (SA) replied:

Haven't you see those batterys that are rated at 68amps and can deliver 200amps.

So many people do not understand batterys, they think you can run it deed flat and recharge it with a standard charger in a matter of hours.

A deep cycle battery should not be discharged below 25-30% of its rated capacity.

The other thing is you don't want to charge most of them at more then 15 to 20 amps per hour....cars alternators will charge at upto 110amps.

For a battery to weigh 17kg with such high output, the 75amp batterys we use weigh 25kg by them selves.

6mm cable is way to small and dangerous.......as said before 10mm minium (6B&S) we try to use 3B&S where possiable.

Why don't you want to mount it under the bonnett.

Regards Richard

Member - Prado Garageo replied:

G'day Tom, I encountered the same issues 3 yr ago. I ended up getting an "Optima" D34 deep cycle battery for $286. it weighs 19.5Kgs & is 120ah. I use it all the time for an engle & it gives me about 2 days when we are stopped, with camp lights etc.. I went to an Auto electritian who fitted the battery into an ex power tool plastic box with all the isolaters and relays inside an array of outlets fitted as well. (silicone is a great glue). He wired up using an "Anderson " Plug which is in the compartment in the cargo area LHS. I had 3 vehicles simarily wired with Anderson plugs and I move the battery pack (& frig) from vehicle to vehicle. The starting battery is isolated from the portable system. The Auto electritian was about $160 for everything. I take delivery of a D4D in 10 days and I wont be changing a thing when I have the new one wired up. It can be done a lot cheaper, than a propietry brand dual battery setup.
good luck.

brett replied:

Can't see how your saving money by mounting in the rear instead of under the bonnet. By mounting in the rear your saving on a tray, about $120, that's it, you will need more cable and probably a box to put it in. Also under the bonnet you can get away with a deep cycle wet cell, cost around $150 or less. I wouldn't put any wet cell in side the car, so you'll need an AGM or similar, cost somewhere between $200 -$300.

brett replied:

I could be wrong but I got the feeling he was worried about cost

tdv replied:

I just went thru similar dilemma. However when you spend 55-60k on a car what is an extra $200 to fit one under the bonnet? Well that was my attitude anyway. There is plenty of space in there. I negotiated it as part of the deal so am unsure of cost. It is a TJM setup with 90 amp/hr AGM.

Cheers

Tez

Member - Prado Garageo replied:

Hi Guys, Interesting how things developed from my earlier post and not being clear enough in my explanation. The Deep Cycle Optima battery is a Gell type and spill free. My installation is all about portability, and moving it from vehicle to vehicle & onto the workshop bench when not in use. The Anderson Plug is heavy enough to carry the amperage. I mentioned the costs for interests sake and I agree to skimp a few dollars on a $55K+vehicle is irrational... however why spend more than necessary ? I actually position the battery pack (which has a 1m lead to get to the anderson plug) in the footwell behind the passenger seat with the outlets facing the door. The Engle sits (above the battery pack) where the rear passenger seat normally is and we access it all from the rear passenger door. I have a toolbox where you would normally place a second battery under the bonnet. I reckon if you put all the posts together you should be able to get a good solution to the questions in your initial post, lastly have a talk to an auto electrician.

Member - Olcoolone (SA) replied:

Now don’t get me wrong, but what is this big deal about making it portable, we have a 60lt fridge mounted in our Hilux.

When we go away the fridge always stays in the Hilux, I would not like to leave a $1000 plus fridge and $400 plus battery pack sitting at a camp site when I’m not there.

What else are you going to put in the Prado when you are away that may require extra room in the back and the fridge to be left behind.

What are you going to charge the battery back up with, if you put it back in the Prado to charge then the fridge is not going to work, you will have to put the fridge in there as well?

You will only get a day out of the battery.

When we go out for the day we always take the fridge with us and we charge the aux battery up as well.

Are you tenting it?

If you put it into another vehicle then you will be paying 3 times the installation cost, you will still have to charge the battery.

Seriously how many times are you going to have to use it out of a vehicle where you need a battery?

Regards Richard