Citizen Eco-Drive Watches: How does it work?
Citizen Eco-Drive watches use the simplest, yet most technically advanced power generating and storage system. Citizen Eco-Drive’s ability to use light from any source to generate electrical power means that the supply is limitless and free.
Most Citizen Eco Drive watches are equipped with a special titanium lithium-ion secondary battery that is charged by a silicon solar cell located behind the dial. Light passes through the covering crystal and dial before it reaches the solar cell. A special Citizen Eco-Drive energy storage cell is used to store the electricity from the converted light energy. With normal care and exposure to light, the owner can be assured of a lifetime of reliable and trouble free power. As an added benefit to the environment, the energy cell contains none of the chemicals used in ordinary watch batteries.
The rechargeable cell featured in Citizen Eco Drive watches is a highly specialized unit. Frequently, it is incorrectly referred to as a “capacitor”. This cell will last up to 40 years. Certainly charge capacity will diminish over time, but even after 20 years, these Eco-Drive cells are rated to retain 80% of their original capacity.
If kept in the dark for too long, some Citizen EcoDrive models engage a hibernate mode, where the hands of the watch would stop running but the internal quartz movement would still keep track of time.