Frankly, I would be terrified to be in something like this in a combat situation. A well-placed or lucky shot could essentially kill power, leaving you a sitting duck strapped to a couple hundred pounds of metal. There would have to be many layers of redundancy and hardening for power and control systems before it would really make sense to put a soldier equipped with an exoskeleton into combat. Frankly, the ability to amplify movement isn't very useful in a modern combat situation (where you would expect to be shooting at opponents at least a few yards away rather than engaging in hand-to-hand), though I can see the applications behind the lines, such as loading vehicles or carrying heavy objects. In many of those cases, you might skirt the battery problem by just having the suit tethered to a power supply - for instance, you might use the suit in a hanger, loading Maverick missiles onto attack planes. You could simply define a work area around each plane, stripe it out on the floor, and then have a power tether drop from the ceiling such that the suited soldier/airman can move all around the plane being worked on and back and forth to storage areas as needed without having to worry about tangling up with another worker or trampling on the power cable.

If you've ever worked on anything complex in the military, you would know that they love redundency.

Of that I have no doubt. My point though is that the technology simply doesn't exist (and barring a truly astounding leap in technology, won't for decades) to create that kind of redundancy without making the suit so bulky and awkward as to be useless. In a combat deployment, a single power source would not be sufficient... two might not even be viable. So where would you put two (or more) power sources, and how would you protect them, and how much efficiency do you lose by doubling what is most likely one of the heaviest and bulkiest components?

If you had it on a self-winding wheel

I was thinking even simpler... ever been to one of those do-it-yourself car washes where the spray wand has a hose on the end of a swiveling arm suspended above the car wash bay? That would keep the cable off the floor to avoid catching on or tangling things, while allowing the suited person to move in a fairly large area all around a vehicle. The hose and arm could be extendible to some degree as well... hell, it could even be an articulated arm that would be smart enough to track the position of the suit, the way the cable is suspended and the location of any obstacles in the space and move the cable to ensure it doesn't catch on anything (I'm thinking about something like the vertical stabilizer surfaces on a jet plane, for instance, that might stick up a good bit higher than the rest of the vehicle, or maybe allow you to work in and around a helicopter without being overly concerned about the location of the rotor blades because the arm would maneuver the cable around them to allow you to move efficiently around the aircraft).