In my experience of winch challenge events in a Land Rover with a Warn 8274 winch, I managed perfectly well with one battery - an Exide Maxxima 900DC spiral wound gel battery. As long as the engine's running and your alternator is working, this battery on it's own will happily haul a Niva. They're very fast recharging and thrive on "heavy" current draw, oh, and I'm still using one that I bought 9 years ago! If you're not using a fridge, I really wouldn't bother with 2 batteries. If you are, then it's safest to have 2, on a simple split charging relay, purely so that an accidental total discharge (say sitting in a camp for 2 days without starting the engine) doesn't leave you relying on a camel tow, ahem;-) 2 of these batteries, the 2nd charged via a 30A relay switched by the alternator charge light wiring, did me fine for a month in Morocco last November, and the one before that!
Last edited by mossproof; 21 May 2012 at 22:20.