Appendix D: Operating Characteristics
Operating the calculator for more than 2 to 5 minutes after this low power indication first occurs may result in calculation errors. The battery pack must be recharged by connecting the HP-80 to its battery charger (HP Model 82002A).
Recharging and AC Line Operation
The HP-80 should be turned off before plugging in the charger. It can be turned on again after the charger is plugged into the power outlet and can be used during the charging cycle. The HP-80 can be operated continuously from the ac line if desired. There is no danger of overcharging the battery.
After 14 hours, a completely discharged battery will be fully charged. Shorter charge periods will allow reduced battery operating time. For convenience, overnight charging is recommended.
To prevent damage to the calculator, the position of the line voltage select switch on the battery charger must be set to the proper line voltage.
1 Turn the HP-80 power switch to OFF.
2 Insert battery charger plug into the rear connector of the HP-80 and insert power plug of battery charger into the power outlet. The HP-80 will not operate when connected to the recharger unless the recharger is connected to a live power outlet.
3 Slide the power switch to ON, see that 0.00 is displayed.
4 Slide power switch to OFF if you don’t want to use the calculator while it is charging.
5 At end of the charging period, you may continue using your HP-80 with ac power or proceed to next step for battery operation.
6 With the power switch at OFF, disconnect battery charger from power receptacle and the battery charger from HP-80.