noun
D battery; D cell
Abbreviation of 単一型乾電池. Used in product labels, shopping, and everyday talk about large cylindrical batteries.
リモコンに単１電池を入れてください。
Please put D batteries in the remote control.
この懐中電灯は単１を２本使います。
This flashlight uses two D cells.
Full formal name; 単１ is the everyday abbreviation.
C battery; the next smaller common cylindrical battery size.
AA battery; the most common household battery size.
Abbreviation of 単一型乾電池 (tan'ichi-gata kandenchi, 'single-type dry cell'). The numeral 1 indicates the largest common cylindrical battery size in the Japanese 単 series.