Outer Limits 4x4 Board

I was wondering what would be better as a 2nd battery a 105ah true deep cycle batt, as i understand it it would take a far while to charge from the cars alt......or a supercharge alrounder which is meant to take less time to charge but also wont run stuff for as long. it says on top of the alrounder that it too is 105ah but the dude at supercharge said that it isn't a true deep cycle and therefore in reality its more like 60ah???????It confused the hell outa me. i also noted that the true deep cycle wont start the car on its own.

You are playing the balancing game... 1. do I want deep cycle battery (lots of AH) capacity, long recharge time, not designed for and may damage by trying to restart motor, somewhat more sensitive to heat and vibration or 2. dual purpose, capable of starting motor, lower capacity (AH), quick recharge time, most are quite robust as far as temp and vibration.
If you are looking to run your camping setup for more than a day trip, overnight etc, then you need to head more to #1. If mainly overnights and travelling each day then #2. Points to remember ... your fridge does not run continuously, you do not use lights all night etc.... I headed for the #2, and with daily travelling have not had an issue with an optima 55AH as my second battery. If I need capicity for a longer stay, I have used a little wind generator, or solar panel to keep the battery charged without running the vehicle.

Hope this helps ... probably just muddies the water.

No that does help so thankyou very much.....I have thought about a solar panel too, i have a storage box that i put on the roof rack when we go away that holds the chain saw and stuff. And i thought about fixing a solar pannel to that. what size solar would be suitable? I have a 40l engel and the usual 12v stuff too.

It is a surface area to mass equation with batteries.

Most starter batteries have many plates (very large surface area) to allow lots of electrons to flow quickly, but these plates are thin and cannot sustain the chemical transformation of the plates during discharge for very long before they are exhausted (no "depth" to the charge, high current output for short period of time).

Deep cycle use fewer, thicker plates (less surface area) and can allow only a moderate amount of electrons to flow off the surface of them. They can however do this for a considerable amount of time due to the physical thickness of the plates and the slower chemical transformation of the plates during discharge.

Therefore for the same weight of lead, a deep cycle will always have more AH capacity than a cranking battery, and the cranker will always be able to throw out more instantaneous current than a deep cycle. Marine batteries apart from their superior physical construction are at a point about halfway between a cranker and a deep cycle, best and worst of both worlds.

[quote="hat size solar would be suitable? I have a 40l engel and the usual 12v stuff too.[/quote]

Consider that the fridge will draw 3A say for 1/2 a day, so need to think about charging at a similar rate. My 40w panel (an old ex teldtra panel) seems to provide enough to extend the life of the battery charge. Modern 40w panels are smaller, so you may be able to get one the size of your box. Remember that for best results you need to point the panel at the sun.

Thankyou guys for your input.