The Segway 2's control unit runs on a CR-2430 lithium ion watch battery. Just thought I'd share that tidbit.
It's not a great design in my opinion to have a non-rechargeable battery. They could have designed in a loop coil with a diode and put in an alternating current magnetic field in the unit so that the field induces a current in the loop and it then could charge a small battery.
If my $50 electric toothbrush can do this why cant the $5000 Segway...