what are you running 11.1v with? if you get and e-revo you will need 2 7.4v batteries run in series connection to create a 14.8v connection. the price on the batteries you can find at www.maxamps.com, and as for the revo check like www.towerhobbies.com for that one. puffing can be caused when the battery is overheated or goes beyond the cutoff point on the cells.