HP HP-21 - Battery Operation; Battery Pack Replacement

Accessories, Service, and Maintenance 55
Battery Operation
Use only the HP battery pack. A fully charged battery pack
provides approximately 3 to 5 hours of continuous operation.
By turning the power OFF when the calculator is not in use,
the HP-21’s battery pack should easily last throughout a
normal working day.
Battery Pack Replacement
To replace your battery pack use the following procedure:
1. Turn the Power Switch to
OFF and disconnect the battery
charger from the calculator.
2. Press the thumbset on the
rear of the calculator in the direc-
tion of the arrow.
3. Let the battery pack fall into
the palm of your hand.
4. Insert the new battery pack in
the direction of the arrow. Slant
the leading edge of the pack into
the edge of the doorway and snap
the battery pack into place.
5. Secure the battery pack by
pressing it gently.