I bought a bunch of those Zippy lipos from Hobbycity. They're great for the price, but you do get what you pay for. In the beginning, they work really well. However, after about 50 cycles, the batteries don't hold up capacity. I used to be able to drain to 4500 mah out of the 5000 mah pack. Now, the battery will only drain down to about 3500 mah. The rest of the amps gets below usable voltage for my 4 cell packs. I don't know how these compare to thunder power or maxamps, but these batteries don't last in the long run. I'm looking elsewhere to see if I can get similarly priced batteries and see how they perform. I can't afford the more expensive batteries so I'll have to keep looking.