Following up on the Lithium polymer battery mention I Googled them and was disturbed to find:
-high fire risk. One seller offers flame retardant bags to put the cells in while charging them... for $25
-(as warned) high prices especially considering the more-unique balanced charger / discharger devices at ~$100 and up being required in addition to the cells themselves
-a hazardous materials uplift for FedEx shipment ranging from $25-$45 depending on destination, on top of normal shipping rates
All of that tells me they're "not ready for prime time" though the current capacity vs weight looks very promising.
I will wait and watch, hoping the technology matures into something safer and less costly as time goes on. Likely it will, particularly the cheaper part, though it appears some safety issues have to be addressed meaningfully.
Thanks for the mention. It is interesting.
Lowell K9LDW