G-Shock is a line of Casio watches known for their durability--specifically, their shock and water resistance. In addition to traditional battery-operated G-Shock watches, Casio also offers a line of solar-powered G-Shock watches. These solar-powered G-Shocks use a solar cell on the watch face to keep the watch's internal battery charged. When this rechargeable battery fails, you may have to pay up to £26 to have it replaced by a jeweller. Luckily, replacing the battery in your solar G-Shock is simple.
Find a flat work surface, like a table or desk, where you can replace your Casio G-Shock solar watch battery. Have a lamp near your workspace to make it easier to see all the watch's small components. Lay your Casio G-Shock watch face down on a piece of felt to protect the watch face from scuffs or scratches during battery replacement.
Direct your attention to the side of your watch band that has the red "G-Shock" button; you must remove this half of the watch band to remove the watch's back cover. Locate the plastic link that secures that half of the band to the watch. Use a watch or optical flathead screwdriver to push the metal pin at the centre of the plastic link. The metal pin will not slide out, but it will slide over just enough to allow you remove the band.
Use a watch or optical Philips screwdriver to remove the four small screws that secure the back cover of your Casio G-Shock watch. Set the four screws aside until you are ready to replace them.
Slowly slide off the back watch cover to avoid losing the three important springs pinned beneath it. Use a pair of small metal tweezers to remove the three springs. Note the placement of the springs, as they are all different lengths. Set the springs aside for now.
Lift the black rubber cushion out of your Casio G-Shock watch with the small metal tweezers. Underneath the black rubber cushion you'll see an identically-shaped white plastic panel; remove it. Set these pieces aside until you are ready to reassemble your watch.
Locate the round battery compartment at the centre of your Casio G-Shock watch. The watch battery is held in place in the battery compartment by a latched round battery strap. Use your watch or optical flathead screwdriver to push the latch to the left, release the strap and free the battery.
Remove the old watch battery with a pair of small plastic tweezers. Promptly discard or recycle the spent watch battery. Insert your replacement watch battery into the battery compartment using the plastic tweezers. Gently push on the round battery strap to snap it into place. Use the tips of your small metal tweezers to short the watch's "AC" and "-" terminals as per the instructions on the round battery strap.
Replace the white plastic panel in your Casio G-Shock, followed by the black rubber cushion. Carefully return the three springs to their correct positions with the help of your small metal tweezers. Replace your watch's back cover, return the four screws to their positions and tighten them to hold the watch cover in place. Reattach your Casio G-Shock watch band by pushing on the metal pin at the centre of the watch lug while aligning the watch lug and band. Release the metal pin to hold the watch band in place.
Keep the small metal components you remove from your Casio G-Shock watch on a magnet to avoid losing them during your watch repair. Many solar Casio G-Shock watch models use a CTL1616 battery, but consult your watch manual to determine the correct type of replacement battery to purchase for your particular watch.
Casio recommends that you have your solar G-Shock watch battery replaced by a Casio authorised dealer. Replacing the battery on your own may void the warranty on your Casio G-Shock watch.