I'm looking to upgrade the battery system of my robots from lead-acid to some other technology that is smaller and lighter (Ni-Mh or lithium).
My robots have 2 power sources. The drive system is powered by a 36-volt system that needs about 18Ah of capacity and needs to be able to put out about 30 amps continuously with bursts around 60 amps. The other power source is a 12-volt system that needs about 100Ah of capacity and needs to be able to put out about 20 amps with bursts of 40 amps.

Questions:
1) Which technology is best for this use?
2) What is a good battery supplier?
3) Does anyone know where I can get flat lead acid batteries? The perfect battery to me would be about 9" wide by 30" long by 2" tall. Does this exist?

Thanks,
Jason
http://www.beachrobot.com