Recharging a solar watch battery is as easy as placing the watch next to a light source. Unlike quartz-powered watches that require a battery change about every five years, the battery in a solar watch theoretically never needs changing. Sunlight or artificial light is needed to recharge the battery. Solar watch buyers should keep in mind, however, that no battery can keep a charge forever, but Casio and Citizen watchmakers have produced solar watches capable of a 16-year life without a battery change.

Examine the charge level indicator on the watch dial. Most solar watches have an indicator bar that gives the level of charge. If the charge indicator bar reads zero, then the watch needs to be recharged. An insufficient battery also is indicated when the seconds hand moves in two-second increments instead of one second, the time can’t be set and the mode buttons don’t work, according to Citizenwatch.com.

Place the watch near a light source, preferably direct sunlight. Ideal placement is on a window sill. Keep your shirt sleeve above the wrist to expose the watch to sunlight if you are active and outdoors. Expose your watch to sunlight while driving a car by keeping you arm on the door ledge with the sleeve pushed up. It takes 20 hours of exposure in sunny conditions and 60 hours in cloudy weather to fully charge the battery.

Expose the watch to an incandescent light source about 20 inches from the solar watch if exposing it to natural sunlight is not practical. However, indoor light sources are generally insufficient to give the solar rechargeable battery sufficient power. It takes 150 hours of artificial light to fully charge the battery.

Expose the solar watch to sunlight for three minutes or artificial light for 3.5 hours to give the watch a 24-hour charge.

Ensure the solar watch is exposed to direct sunlight or artificial light every day to maintain the temporary charge and to ensure eventual full charge.

Ensure the solar watch reaches a minimum charge of 85 percent before stopping exposure to direct sunlight.

Reset the time if the watch has reached the no-charge level. Pull the crown on analog models all the way out. Leave the crown out for 30 seconds. Close crown flush against the case edge. Set the time.

Pull the crown out on digital models, such as the Citizen versions, and the hands will move around the dial.

Press the 2 o’clock and 4 o’clock buttons at the same time. The display lights will turn on and the hands will move again. Press the 2 o’clock button alone to change the hours, minutes and seconds display.