Ultra Light 12V 3.5 Ah Packs: Where to Find?

[ank_gl]

can anyone suggest some ultra light 12V 3.5 AmpHour packs?? where can i get em??
COST is not the issue, weight is

 

[mgb_phys]

Lightest batteries for a given power are usually lithium.
Where from depends on where you are.

 

[berkeman]

Batteries.com is a pretty good website for buying all sorts of batteries:

http://www.batteries.com/index.asp

 

[rcgldr]

Li-Poly battteries are the lightest for the amount of energy stored. You'll need a special charger. Mis-charged, Li-Poly batteries will explode.