Good morning fellow Bitogers on this chilly morning in central Florida. The situation: Behold the "Luv" machine. For those of you not in the know, the "Luv" machine is a 1986 Chevy Astro Van with the 4.3 V-6 motor. I use it as the family "mule" on what is left of the family farm. Among the many things it doesn't have is an alternator. The bearings on the alternator went out about two years ago so I removed it and have been running on the battery ever since, (my fan belt is a pair of my wifes panty hose tied tight around the crankshaft pulley and the fan pulley). Since the battery receives no charge while the engine is running, I can get about two hours of use before it finally drains to the point of not working and needs a recharge. What I've been doing is swapping batteries from the tractor to the "Luv" machine while the dead battery recharges and then swap back again and so can keep working all day. The question: How can I hook two batteries together so that I end up with a large battery that will run longer? I plan on re-routing the cables so that they come up inside the cab next to the drivers seat, (I already have long cables in my scrap box). Then my idea is to build a simple box out of scrap 2 x 4's and scrap plywood and secure this to the floor via self tapping screws so the batteries don't slid around. I'm pretty sure I would connect positive to positive and negative to negative to make a long lasting 12 volt battery. Is this correct? Do the batteries have to be the same size? (cold cranking amps, etc) or can I mix and match? Will this double my running time or will it merely add to it? (say like another hour). Does it matter if one battery is older than the other? Any and all help in tackling this project before I get started will be greatly appreciated. Oh, and BTW, before anyone suggests, I'm not going to install another alternator. If you saw the "Luv" machine, you would understand.