Nike, founded in 1978, has moved from a small sports store in Oregon to one of the largest athletic manufacturers in the world. Nike Timing, the division that focuses on watches and stopwatches, keeps full manuals and battery instructions available online. Most Nike watches are not user serviceable, due to the sealant that keeps them waterproof and the need to remove the band. However, watches with a small circle on the back of the watch for battery removal can be changed by hand.
Place the watch face down on a soft cloth. This will keep the crystal and front of the watch safe while working on the battery.
Locate the small metal circle on the backplate that can be removed. It has an indentation in the center for turning, and has open and close location markings along the edge.
Place the small coin in the indentation, and rotate the metal circle towards the open marking. This will allow the circle to be removed from the watch back.
Remove the exposed battery. Replace in the same orientation with the replacement battery. Be sure to keep the positive side (labeled with a + sign) toward the top.
Place the metal circle back into the hole in the watch, then use the coin to rotate the circle from open to closed.