The Kurzweil PC88 keyboard features 64 internal sounds, 32-note polyphony, the ability to layer up to four tones simultaneously and a number of other features, according to Kurzweil. The keyboard is designed to be portable and self-contained, able to function on its rechargeable battery pack for several hours. However, over time the battery will lose some of its charge capacity. The battery lifespan can further diminish if you drop the keyboard or accidentally spill liquid near the battery casing. Fortunately, you can replace the battery in just a few minutes.
Turn off your Kurzweil PC88 keyboard and unplug it from the electric wall outlet.
Disconnect any external audio devices connected to the keyboard.
Remove the nine Philips-head screws on the keyboard's back casing.
Turn the keyboard upside down.
Remove the nine additional Philips-head screws near the back end of the keyboard's underside. There are 19 screws on the underside of the casing, but you want to leave the 10 front-most screws intact. It will be fairly obvious which screws you want to remove, because the underside has a large seam separating two different parts of the casing.
Depress the two plastic latches on the far left and right sides of the Kurzweil PC88 casing.
Slide the casing off of the keyboard.
Pull the lithium battery out of the battery compartment. There are no wires connecting the battery to the keyboard; it simply snaps into place for a contact charge.
Place the new battery in the compartment. Kurzweil PC88 keyboards use a standard 3-volt CR2032 lithium flat disc battery. These are available at many battery stores and some electronics dealers.
Place the casing back on your Kurzweil PC88 keyboard and press down until you hear the plastic latches snap into place.
Reinsert all 18 screws.