This is a good one! Starting failure w/ 2yr old battery. Found thick, damp chemical deposit completely covering positive battery cable clamp and adjacent fuse assembly (3"away) within cable. Positive cable clamp almost completely erroded. No fluid in one battery cell closest to positive terminal. Last battery had no fluid in same cell. May have software issues due to past intermittent electrical problems. Why is this battery losing fluid?
When your battery is providing power, particularly during heavy load like starting, tiny droplets of acid and acid gassed leak out upwards and react with the moisture in the air and the copper and lead in the terminals and wires. Some batteries are worse than others, probably a battery to battery variability rather than a name brand thing. Have you ever seen the felt discs that they sell to go under the terminals, these are an attempt to slow down this decay. Its possible this battery is leaking more than most, and obviously you are going to replace it, but that's why some batteries leak and corrode other nearby metals. Was the last battery the same brand? If so change brands. But it is also possible that the second battery leaked faster because of the resistance in the cable caused by the issues started in the first one. Definatly replace both the ground and the positive cables when you replace the battery along with the terminals if you don't get them with the cables, and do use the grease on the terminals. If you don't let the metal have a chance to react with the acid, you'll stand a better chance. Also, make sure your tie down is good so the battery doesn't walk around, and it's always a good idea to have the battery sitting on plastic or an insulator rather than your bare frame. Finally, make sure the ground is completly clean when you put on the new cable.