I haven't kept up with battery technology from when i last looked at any of this stuff. Batteries have come on in leaps and bounds from the need for laptops and hybrids though! Fuel cells are still progressing slowly...
The trick with high performance motors is to run them at as high an RPM as practical, to push up power-to-weight. This is made easier with the latest generation of brushless DC motors, which use
Insulated Gate Bipolar Transistors to replace the commutator for very high speed switching. Designs are stuck with about 1 Tesla magnetic field strength from
NdFeB magnets, until
liquid nitrogen cooled superconductors become more widespread, so the best designs pack in the most amount of copper for the least amount of iron magnetic return circuit. This all leads to high voltages (>1000V).
Dave, this is a good area to get into. If you stick to electric you will be ahead of the curve when the industry eventually swings this way. I've changed my view since i became aware of this emerging technology:
http://www.eurekamagazine.co.uk/arti...l-engines.aspx
http://www.powerchips.gi/
PowerChip technology is working it's way down from the space industry, so is still cost prohibitive. The performance numbers add up though...