Deep cell batteries

Before deciding on a Deep Cycle Battery you need to consider your charging system.
You will need one that completely isolates the D/Cycle battery from the Cranking battery on your car, before charging it.

As far as I know you can't just charge using a parallel charging system to charge dissimilar battery types. For this reason I have gone the expense of a Rotronics Battery system, which actually allows for dual battery on the car and one in the camper. It recharges the batteries individually therefore you can have mixed types of batteries in your system.

There are more knowledgeable people than me regarding this subject on this forum.

Another valuable resource you may want to look at is the Camper Trailer Group on Yahoo. Between that group and this Forum you have all aspects of campertrailers covered.

http://autos.groups.yahoo.com/group/campertrailers/

Should be no problem with a deepcyle battery in the camper except you need to pay attention to the wiring and charging regime. There has been heaps and heaps of discussio on this topic so if you do a search you'll have enough reading to keep you off the street for a week.
Try this web site for some ino:-
http://www.windsun.com/Batteries/Battery_FAQ.htm
Also get hold of Collyn Rivers' book "Motorhome Electrics & caravans too.
To your question the size depends on how much space you have, your intended use and how you expect to recharge the battery.
If your budget will allow, Solar seems to me to be the best way to go but again you need to work out how much power you will consume per day. If you are only charging the car while driving there are quite a few thing to be aware of.

Some more reading material:-
http://www.uuhome.de/william.darden/index.htm

Thanks for that, very informative. I can add up the amount we will use.
Solar may well be the way to go.

PBob, you have some good advice already. Here is my experience:

I have a 100AH wet cell Federal under the bonnet and two 120 AH AGMs in the camper trailer. For the CT, the most important thing is to use heavy duty cable for charging. I used double insulated 20mm squared welding cable which I ran through the chassis rail to a 175 amp Anderson plug. My fridge is in the back of the Hilux. I have one 10mm squared cable pair running from the DC under the bonnet to a plug beside the fridge. Also have another 10mm squared cable pair running from the CT batteries via another Anderson plug to another plug beside the fridge. I can therefore choose where I draw the power from.

Running the fridge (50ltr Reefer DTV), water pump, lots of lights (we have 4 plug in lights, plus 4 built in to the CT), we have never yet run out of power. Although we don't waste power, I don't fret about it either. I reckon we could sit still without charging for 6 or 7 days with no worries. I carry a 1KVA Kipor generator, but it is rarely needed.

AGMs are ideal for the CT. They charge quickly and hold their power well when not in use. They do not need to be kept on trickle charge when at home. They can also be stored and used on their side. We use one on its side under a seat in a canoe to power the electric motor.

From my experience, there is no problem charging wet cell cranking battery, wet cell DC and AGMs all in parallel. You just need to isolate when motor is off. If you do lots of short trips the wet cells might not charge properly as the AGMs might be drawing all the charge current. But if you do some long trips (say over an hour or so) there seems to be no problem. I've had none anyway. I've just used a continuous duty solenoid for isolation. Collyn Rivers suggests using a Redarc or similar voltage sensing isolator to avoid the problem of the AGMs sucking all the charge current if you do a lot of short trips.

I'd put in the biggest AGM you can fit / afford. I doubt you would regret having too much power, but you might regret not having enough.

Hope this helps.

Thanks norm, excellent advice and much appreciated.

Thought I'd mention Collyn Rivers has done a new book specifically for camper trailers, I have one myself and went to buy the Motorhome edition but he advised the Camper Trailer edition would be out in a week or so now so I will get that.

Based on the research I have done, mostly using this site as a reference point here is what I'm intending to get, I want the book to clarify a few things and deal with mounting the panels and what not.

GMC 850 Generator 98 Bunnings
Steca PR1515 225http://www.au.store.yahoo.com/solaronlineaust/stec12asolre.html
Uni Solar 64 560http://www.awardcaravanaccessories.com.au/
Switchmode 12V 12 Amp Charger 99.95http://www.jaycar.com.au/productView.asp?ID=MB3612
FullRiver HGL120 (130 AH) 289http://www.lakecomm.com.au/batteries.html
ST2 - Two Modules Solar Tracker 462 http://www.solarvalley.com.au/solartrackers.htm

I want the tracker as a good secure mount will cost about 150-200 dollars anyway, for 462 and so not much more for a heap more sun hours. It also means I can get anouther amperouse panel and easily mount it if I want.

To start off with I'll use the solar and see how I go, that's why I'm getting a decent regulator to keep an eye on things, if I need to use the genny for an hour or so to keep the battery up then so be it it's only 60 dB and I reckon a bit of radio at dinner time will mask that easily enough. I'll but another panel and another battery down the track if needed.

Have done the amorphous/crystaline thing and reckon the amorphous is the way to go cause I live in Queensland and like to camp in summer. Also it's tough as old boots so I don't have to worry about it breaking.

AMG battery IMO is a no brainer as it is safe and the benefits for this type of application are apparent.

Other than the right heavey duty cabling and a decent mount on the A frame that'll be it unless the book shoots it down too much.

Much thanks to Jimbo/Jumbo, Collyn Rivers, Mainey,Mike DID and lotsa other peeps who helped me get to this point, also that fella that changes he's name a lot and wants to sell stuff he's got some good things to say and played a good devils advocate.

Hope this helps.

Yep I appreciate the input Mainey, I figure loose 25% for the dodgy rating and conditions, that puts it back to 48 Volts, so about 4 amps an hour, so say I got 5 peak sun hours, then 20 amps, add the tracker and I should be able to get a 30-50% increase, say another 6 amps on 30%. So for the one I should only have to run the genny every few days (to tell the truth I’m only going to be using about 35 per day to start), so hopefully that will be sweet with a bit of light genny work. Then add the other cell and that should pull me up to where I want to be.

Fact is I need the book to clarify this (to get the PSH and other bits) and I haven’t seen any real life tests with the tracker, just what is quoted and I hope the tracker does it's job well. Haven’t bought yet but that's the plan ATM, I agree I'd like to get a larger amorphous panel to be safe but I don't think they sell over 64 cause of the size?

Anyways, based on the above I should be getting over 50 with 2 panels and 2 batteries which will still mean a little genny work for a long stay but will be close enough I think. I know I'm sailing close to the wind but as I got the genny I'm not too worried. When I get the 4x4 I’ll rig the second up to the alternator as I’ll prolly be using it most days, and reckon I’ll be able to do away with the genny completely but keep it as an emergency of course.

Cheers and beers.

Hi PBob, beware, there are a lot of myths surrounding battery use and charging.

Without having to lay out too much money, you can fit a decent size battery and your vehicles alternator will easily and regularly charge it back to 90 to 95% and the only thing you have to make sure of is that your existing charging system, thats your vehicle’s alternator and regulator are in good condition and you have suitably thick enough cable, both positive and negative, running between the front of the vehicle and the camper trailer, you will have no problems charging up even a large battery as you drive along.

The only governing situation is the amount of time you drive for, obviously the longer you drive, the higher the charge capacity your battery will have when you stop.

A drive of around 3 to 4 hours, even with the battery starting out at say 50% charge, will get the bulk of the charge back into your battery.

A drive of 7 or 8 hours should put your battery back above 90%.

There is no reason for isolating ANY battery from the charge system while you are driving. An alternator of 85 amps or higher, can happily handle two or three batteries at the same time and charge them all as pre what I posted above.

The only thing you need to consider is the type of isolator to use for protecting your starting battery when you turn your motor off.

Cheers