Sunday, Feb 24, 2008 at 20:26
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 | J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein
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Follow Up By: Member - jjt98 (QLD) - Sunday, Feb 24, 2008 at 23:05
Sunday, Feb 24, 2008 at 23:05
Thanks for the advise
John. Much appreciated.
Cheers
Jason
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