充 is used in: 充电 (to charge), 充满 (to be full of), 充足 (sufficient), 充分 (ample), 补充 (to supplement), 冒充 (to impersonate). Very common in modern contexts with 充电 for device charging.
Top lid stroke - a horizontal cap that often sits over a body or vessel in compound characters. Here it suggests a covering or topmost layer pressed down on the figure below. Used decoratively rather than semantically in this character, but its position marks the visual ceiling of the form.
Bottom 允 carries the sound, drifting from yǔn to chōng in an older pairing. It also reads as a person standing upright, which combined with the top lid suggests a vessel filled to capacity - the source of 充's 'filling, replenishing, serving as'. Indexed under Kangxi #10 儿 via the leg-strokes at 允's base.
Filed under radical 儿 (ér, #10) by convention. 儿 is not a separate component in 充, so no strokes are highlighted.
