Checking The Backup Battery - IBM ThinkPad G40 Hardware Maintenance Manual

Checkout guide

Checking the backup battery

The backup battery is rechargeable.
To check the backup battery, do the following:
1. Power off the computer, and unplug the ac adapter
from it.
2. Turn the computer upside down.
3. Remove the battery pack (see "1010 Battery pack" on
page 63).
4. Remove the backup battery (see "Checking the battery
pack" on page 39).
5. Measure the voltage of the backup battery. See the
following figure.
v If the voltage is not correct, recharge the backup battery
by connecting the ac adapter to the computer for one
hour.
v If the voltage is still not correct, replace the backup
battery.
v If the backup battery discharges quickly after
replacement, replace the system board.
Note: The backup battery, which is used to preserve
configuration information, such as the date and
time while the computer is turned off, is depleted.
40
ThinkPad G40, G41
Terminal Voltage (V dc)
+ +2.5 to +3.2
- Ground