How to choose the right LiPo battery for your drone or robot

LiPo batteries are described by three numbers: cell count (S), capacity (mAh) and discharge rating (C). Cell count sets the voltage: each cell is 3.7 V nominal, so a 4S pack is 14.8 V. Match this to what your motors and ESCs are rated for. Capacity decides flight or run time, but more capacity also means more weight. For a 5 inch FPV quad, 1300 to 1500 mAh 4S or 1100 to 1300 mAh 6S is a common sweet spot. The C rating multiplied by capacity (in amps) gives the maximum continuous current. A 1500 mAh 100C pack can in theory supply 150 A. Choose a pack whose rating comfortably exceeds your peak draw. Always charge with a balance charger, never leave charging batteries unattended, store packs at around 3.8 V per cell, and retire any battery that has puffed up.