I always carry a spare machine with me. Funny thing, in what, 50 something years of playing in the dirt, I cannot remember a single time the primary machine quit and I had to use the backup. With some of the older, no vdi machines I have to admit I would take a break, turn the machine off to conserve the battery, then go for 50' with the blasted thing still off. But I really wouldn't admit to that. On the other hand I don't know what I had for breakfast yesterday. (Actually, I do.)