Have been using zippys, but their C rating is not as advertised. Fine for flying light loads (cx760 - 55A on hover - get 10min landing at 8000mAh used), but I run out of volts before I run out of mAh's when flying heavy loads (7D, etc - 65A on hover). Still get 6min flight time though, landing on 14.5v , using 6000mah (of 10000mAh) when using 2x Zippy 5000mAh 30C (claimed). Looking to try out the Quadropower batteries to compare, before deciding. Ideally I'd like to fly 5 min with a single 6200 or 6600 QC battery, with cx760 on board, then also have the option to fly 2x 6200 or 6600 QC batteries, when longer flights are needed. So which is better? QC 6200 or QC6600 ? Looking at the description it would seem the 6600 is the newer technology, and slightly better . longer life (more cycles?)