Like said above it is usually only one batt that is dying, so if u have one car as a donor and a dead deuce,try it on ea. one, there are so many threads on this its silly, but here it goes, u can use one standard jumper cable and 2 deuces, make believe the 2 batts are only one, and just jump to the outsides, so its 24 to 24 simple, U can use 2 sets of jumpers one set on each batt, U can use 2 separate cars and 2 sets of jumpers to a deuce, u can put multiple battery chargers on each batt as long as they... meaning each output added together does not go over 12 volts, U NEVER need to remove any cables at all from the 24 volt system to charge with 12 volt batt chargers on each one, it is important to clean and pull your batts once a year and chege fully with a quality charger and rotate them in the box, one batt always takes more charge, yes it does, the batt getting the juice from the alt gets it first and over time the second batt becomes lasy or sulfated faster because it is always a little lite on charge, very very true in 4 batt systems also, there is usually one lazy batt, if they are not rotated, the best on board way to charge is with a batt charger for each batt, I always on the M925 put a 4 batt charger hooked on ea. one when stored, and keep a 24 volt charger desulphator screwed to back wall connected to back of slave , for emergencies, and will eventually put 4 charger desulphators along the back wall behind the passsenger seat,and hook one to ea. batt and then wire all ends to one plug, size of cables is important but u sure can use what U have, its like filling a pool, the juice is going over, even if they are junky, but be careful of over heating them,