Notso replied:

There's a whole heap of differing views on this, some of us use a hybrid type which is half cranker and half deep cycle I suppose is the best way to describe it. Others swear by AGMs and the marine types. Some just put a second battery the same as their main.

Probably best to get some professional advice.

obee replied:

I use the battery from the boat. It's there and might as well do some work while it grows old waiting for the next trip on the water.

Owen

Member - Lance S (VIC) replied:

jjt98, i use a trojan 27TMX deep cycle to run lights and 110lt weaco.
cheers,

Lance

Member - Norm C (QLD) replied:

Jason, as Notso said, there are lots of opinions on this. I swear by AGM batteries. No maintenance, you can carry and use them on their side, fast charging etc. If you are not familiar with them, there is some info on them here:
Fridge and Solar AGM Info

Lots of other good info on this site also if you look around.

Norm C

Isuzumu replied:

We use the jump start/portable battery brought from super cheap 900 cranking amps around $60 it portable easy to charge and last for ages. Great to if you have a flat battery in your vehicle. We carry two and have had them both now for five years.
Also we use them for the show pump where the show tent is away from the main battery.
Cheers Bruce.

Member - John and Val W (ACT) replied:

Jason,
As others have said there is a big diversity of opinion in this area. Personally I'd settle for a deep cycle, though the extra cost of a marine battery may be justified if you are going to rely on it to start the vehicle in an emergency. My view is that you should avoid carrying liquid acid inside your vehicle and camper trailer. That rules out the cheaper liquid filled batteries, so you're looking at gel or AGM, and for the larger sizes means you're looking at an AGM. These will cost.

For running the fridge I'd suggest a 100Ah size, though for lighting you maybe could go smaller. (My fridge consumes about 2/3 of my total rig demand.) To charge them you'll need heavy cable - at least twin 6mm to reach from the engine bay back to the camper trailer, and preferably bigger. An option which might be worth considering is to connect your two new batteries together with good heavy cable, so that you use them as if they are a single battery running both fridge and lights.

You'll need good solid anderson plugs to couple the trailer to your vehicle.

I think the main issue you'll strike trouble with is charging the batteries, especially the one in the trailer. You really need a slightly higher voltage than the alternator will normally supply, and you will have additional voltage drop in the cabling.

You mention longevity and performance. Longevity is strongly affected by how deeply you discharge your batteries and how long they are allowed to remain discharged - marine, deep cycle, cranking, this applies to all of them. Being able to fully charge them is important. I'd suggest carrying a good 3 stage charger and topping them up whenever you can. Also, carry a voltmeter and check on the charging voltages. To fully charge a battery will call for at least 14 volts at the battery terminals, 14.4 is good, or for calcium doped ones over 15V. The vehicle alternator is not intended to supply quite these voltages, and is temperature compensated to reduce the voltage to suit the cranking battery when it gets hot. My batteries rarely see more than 13.8V from the alternator, and then only when it is cold. (I carry solar panels which deliver the higher voltage required to fully charge the batteries.)

Sorry if all this sounds pretty negative, but it may save you hassles if you can learn from other people's mistakes!

HTH

John

rumpig replied:

previously i had one of the hybrid cranking and deep cycle batteries for running my fridge. in the 2 and a half years it lasted i started my car once with it, have just changed to a 115ah deep cycle only battery, i recon the extra 35ahs this battery has will be better suited to running the fridge for longer periods.

Benno77 replied:

Just as important as the battery choice is the way you are setting it up. I have a rotronics dual battery system which manages the priority of charge to the crancking battery first and takes all the guess work and human error out of the manual switch. There are a heap different brands on the market and will cost aroun $100-$300 and well worth it too.

Muzzgit [WA] replied:

I have had three batteries in the patrol and I am now using an N70ZZ Exide extreme. It is a cranking/deep cycle wet lead acid type and I am very happy with it.

I previously had a wet lead acid deep cycle and I found that after being camped up for a while and the battery was reasonably well discharged it took a hell of a long time to re-charge.

Next was a sealed cranking battery, and while that one behaved much better, it didn't like the heat of the engine bay and it leaked acid down the inside of the engine bay and onto the chassis. It cost me about five hundred bucks to get everything cleaned up and re-painted.

John S (NSW) replied:

Jason,

I went through this last year. In the end i bought an AGM 100Ah deep cycle. Cost me $320 but worth every cent. 12 months without charge and I use it every now and then for 12v power when working on the vehicles and during blackouts - it still has 11.5v charge in it.

Super fast recharge and can run my 80ltr Waeco & 2 Torpedo lights for two days without problems.

AGM 100Ah Deep Cycle