off-color battery / Battery

Off-color Battery is a battery concept which allows people to know how much quantity of electricity is left. When energized, the green cover on the top of the battery takes chemical reaction and changes color. With more energization, the green cover slowly turns to red. Comparing the colored cover with the color bar on the side of the battery, users are able to know exactly how much quantity of electricity is left, which brings convenience in daily life.
Much more electricity would be wasted when battery of different quantity are used together, so this design also helps to save battery.