Unlike most watches, there is no traditional silver oxide battery in a Citizen Eco-Drive watch. Citizen Eco-Drive watches use light (natural or artificial) as their source of power, meaning they have no actual battery. Instead, they have a solar conversion panel and an energy cell that work together to convert light to electricity, which is what the watch runs on. Although Citizen refers to the energy cell as a "secondary battery" in their literature and manuals, this wording can be misleading.
Understand how your Eco-Drive works. If your Eco-Drive watch stops completely, loses time or ticks erratically, it needs to be recharged, which can be done by exposing it to light. Ideally, the watch should never stop, since it will remained charged up by normal day-to-day exposure to various sources of light as it is worn. However, if the watch does not receive enough light (if it is left in a box or drawer, for example), it will lose power and need recharging.
Determine the amount of time and sunlight needed. The time required to recharge varies slightly by model, so consult your manual or the Eco-Drive website (see References) for details. Outdoor light is recommended for recharging your watch once it has stopped completely. Per Citizen's Eco-Drive website, approximate recharging times are: Outdoors, cloudy: 9 hours; Outdoors, sunny: 3.5 hours
Place the watch in sunlight. Select a spot that offers as much direct sunlight as possible, such as a windowsill, patio, porch or other sunny area. Make sure the watch won't be exposed to water or dampness, potential thieves, small children, or pets or animals. Leave your watch in the sun until it begins running.
Reset your watch. After a full recharge from a low- or no-power state, the watch will need to be put into All Reset mode or set to the "O" position, or the watch may not run properly. How this is done depends on the watch model, so refer to the manual or get instructions from the Citizen website (see References). For many models, an All Reset is done by pulling out the crown to the time setting position and waiting about 30 seconds, then pushing the crown back in and setting the time. However, for perpetual calendar, multifunction and specialty models, refer to the manual or website.