HP -225 Owner's Manual page 150

Power and Batteries
The calculator is shipped with alkaline batteries. A fresh set of three
alkaline batteries provides approximately a year of normal use. How-
ever, expected battery life depends on how the calculator is used;
frequent, long calculations require more power than short, periodic
calculations. For any level of use, mercury and silver oxide batteries
last about twice as long as alkaline batteries.
Use only fresh button-cell batteries. Do not use rechargeable batteries.
The following batteries are recommended for use. Not all batteries are
available in all countries.
Alkaline Mercury Silver Oxide
Panasonic LR44 Panasonic NP675 Panasonic SR44 or
SP357
Eveready A76 Eveready EP675E Eveready 357
Varta VI3GA Toshiba NR44 or Ray-O-Vac 357
MR44
Duracell LR44 Radio Shack NR44 or Varta V357
MR44
Duracell MP675H
Low Power Indicator
When the low battery annunciator (§-J) comes on, you should re-
place the batteries as soon as possible.
142 A: Assistance, Batteries, Memory, and Service