HP 48g Graphing Calculator - Manual (Page 441)

Under typical use, a RAM card’s battery should last between 1 and
3 years. Be sure to mark the card with the battery-installation date,
and, in case the RAM card is not in the calculator when the battery
needs replacement, set an alarm for 1 year from that date to remind
you to install a fresh battery. RAM cards do not come with a battery
installed.
Changing Batteries
The HP 48 uses the following kinds of batteries:
■ Calculator Batteries. Any brand of size A AA batteries. Be sure
that all three battenes are of the same brand and type. (The use of
rechargeable batteries is not recommended because of their lower
capacity and short low-battery warning time.)
■ Plug-In K.AM Card Batteries. 3-volt 2016 coin cell. (Not used in
the HP 48G.)
To replace calculator batteries, use the steps below. To replace RAM
card batteries, see “To change a RAM card battery” on page A-7.
CSUtion
Whenever you remove batteries from the calculator,
be sure the calculator is off, and do not press the
key until the new batteries are installed. If you press
fôî^ when batteries are not in the calculator, you
may lose all calculator memory.
To change calculator batteries:
1. Turn the calculator off. You may lose memory in the calculator and
plug-in RAM cards if the calculator batteries are removed when the
calculator is on.
2. Have three, fresh size AAA batteries (of the same brand and type)
at hand. Wipe off both ends of each battery with a clean, dry
cloth.
Support, Batteries, and Service A-5