Powerpack

You have to decide what you want it for, one to jump start the vehicle with a flat battery or one to run camping accessories as a stand alone unit.
Two different animals and if using one for th latter use the bigger the better but recharging without mains power can be a problem.

Question first:

Why do you need it ?
What capacity do you NEED ?
What will it be required to power ?
What method of recharging will you use ?

Mainey . . .

Hi Andrew
I assume you mean a battery box type power pack.
I just bought a 100 amp amp hr deep cycle battery and put it in a plastic battery box, and fitted the box with circuit breakers feeding an Anderson plug, polarised "T" socket and a couple of cig lighter sockets. To charge when mobile, I just connect in parallel (via Anderson plug) with the second vehicle battery (via a redarc system). When home or when power available I charge with a 3 stage charger. It seems to work for me.
Regards
Neil

Andrew,

A couple of products for you to consider.

Flyer from ABR an advertiser on ExplorOz. With this you need to add the cost of whatever battery you decide to put in it.

Blue Apple Thumper

I personally have a75Ah Thumper which also doubles as a serious jump starter pack. Comes complete with an in-car charging pack.

Bill

I built my own pack using 2 second hand gofer batteries. These are cheap from shops that service the machines.Mine cost $20 each, and if you ask them nicely they may load test them for you.

They are 38 AH gell cells wired in parrallel and power the waeco, lights, shower and laptop. I built a timber box that contains the batteries, solar controller, trailer plug on the side to power up the van and suitable plugs for 12V our an solar panels in.

This has served us well for the last few years.