Invicta watch batteries have a long lifespan, but if you have your watch long enough, you eventually will need to change the battery. Typically you need a tool to pry open the watch and change the battery. Fortunately, prying open the case back is not the only way to change the battery on an Invicta watch. You can change the battery on your own without a tool.
Place the watch in your palm face down. Grab the edges of the case back of the watch with your fingertips. Turn the case back of the watch counter-clockwise until it comes free from the case. If you have difficulty turning the case back, use a rubber gripper (jar opener) and attempt to turn the Invicta case back again. Once you have opened the case back of the watch, pull the rubber gasket out from between the watch case and the case back.
Locate the battery inside of the open case back of the watch. The Invicta battery is round and silver. It can be found in a secured holder that has a spring or small strap which holds the battery in.
Remove the battery. Loosen the screw (do not remove it) on the strap by turning the screw counter-clockwise. Use a credit card or your fingernail to loosen the screw. If the battery is secured by a spring, put your fingernail between the battery and the spring and pull up to remove the battery.
Examine and clean the battery compartment. Look for acid spills from the old battery and clean the interior of the watch case back (battery compartment) with a clean cloth.
Install the new battery into the holder. Grab the battery with your fingers and gently drop it into the battery holder and tighten the screws on the strap. Replace the gasket and then the case back.