I've been screwed by cheap ebay batts, had some 7 cell 3000's from "AmondoTech" that were sheer garbage and were outperformed by my Radio Shack 2000's that got really hot every time I ran them. Eventually the AmondoCrap's oozed white junk all over my Pede's chassis and began making angry sizzling noises so I chucked them in the trash and never looked back.

Get some packs made by a real company, it'll be money well spent.