WHAT ABOUT “S”?
As we just discussed, NIMH and Lipo packs are often referred to by the number of cells in the pack: for example, “2-cell” or “3-cell.” You may also see or read about Lipo packs with a designation such as 2S, 3S, 4S, etc. In this case, the “S” refers to series, and indicates that the cells within the pack are connected “positive to negative,” as in the illustration at right. Some Lipo packs feature cells connected both in series and in parallel, which is designated by a “P.” For example, a “2S2P” Lipo pack would have two pairs of Lipo cells inside. Each pair would be wired in parallel (2P), and the two pairs would be wired together in series (2S). Is your head hurting? Don’t worry about it. Nearly every RC Lipo is wired in series and simply referred to as 2S, 3S, 4S, etc.