Cell count (S)

Cell count tells you how many cells are stacked in series inside a LiPo pack. Each cell has a nominal voltage of about 3.7 volts and a full charge voltage of about 4.2 volts, so the total pack voltage is the cell count multiplied by those numbers. A 4S pack is nominally 14.8 volts and fully charged around 16.8 volts, while a 6S pack is nominally 22.2 volts and about 25.2 volts full.

Higher cell counts push more voltage through the motors, which generally means more power and speed for the same current draw, but the flight controller, ESC, and motors all need to be rated for that voltage. Mixing components rated for different cell counts is one of the most common ways new builders damage electronics, since a part rated for 4S can fail immediately on 6S.

Beginners often assume a higher S number is simply better, but a heavier pack with more cells adds weight and cost, and small frames are not built to carry it efficiently. Checking the cell count printed on every component in a build, from the flight controller to the battery connector, avoids a mismatch that can damage the whole setup on the first flight.