O.K. I must admit that the idea of battery powered suitcases like the LiveLuggage power assisted (PA series) tickles me pink. I have done more than my fair share of long haul traveling and if there is one thing I hate, it is lugging a heavy suitcase around. Sure, you can get wheeled bags, but even they require a bit of muscle power, especially if A to B is a particularly long distance.
A single charge will get you 1.5 miles of unassisted baggage pulling, with a bag that weighs up to 36kg. That is about as far as you are likely to have to go in most circumstances. It packs a 12-volt NiMh battery and weighs in at a hefty 10.6kg and there is the problem.
While a lot of U.S. based airlines are pretty lax on weight restrictions, there are some countries that are very, very strict. In most cases 20kg is the maximum and should they decide to hit you with those excess baggage fees, you will be paying through the nose at a price that makes FedEx International Priority rates seem reasonable.
If you go to Australia it can be even worse. Throwers have been threatening to stop handling any luggage over 20kg due to occupational health and safety concerns.