Lenovo ThinkPad X121e Safety and Warranty Guide - ThinkPad X121e - Page 36

Checking the backup battery, If the voltage is more than +11.0 V dc

Page 36 highlights

4. If the voltage is more than +11.0 V dc, measure the resistance between battery terminals 5 and 7. The resistance must be 4 to 30 K Ω. If the resistance is not correct, replace the battery pack. If the resistance is correct, replace the system board. Checking the backup battery Do the following: 1. Power off the computer, and unplug the ac power adapter from it. 2. Turn the computer upside down. 3. Remove the battery pack (see "1010 Battery pack" on page 50). 4. Remove the backup battery (see "1130 System board assembly, fan assembly, and backup battery" on page 65). 5. Measure the voltage of the backup battery. See the following figure. Wire Red Black Voltage (V dc) +2.5 to +3.2 Ground • If the voltage is correct, replace the system board. • If the voltage is not correct, replace the backup battery. • If the backup battery discharges quickly after replacement, replace the system board. 30 Hardware Maintenance Manual

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4. If the voltage is more than +11.0 V dc, measure the resistance between battery terminals 5 and 7.
The resistance must be 4 to 30 K Ω. If the resistance is not correct, replace the battery pack. If the
resistance is correct, replace the system board.
Checking the backup battery
Do the following:
1. Power off the computer, and unplug the ac power adapter from it.
2. Turn the computer upside down.
3. Remove the battery pack (see “1010 Battery pack” on page 50).
4. Remove the backup battery (see “1130 System board assembly, fan assembly, and backup battery” on
page 65).
5. Measure the voltage of the backup battery. See the following figure.
Wire
Voltage (V dc)
Red
+2.5 to +3.2
Black
Ground
If the voltage is correct, replace the system board.
If the voltage is not correct, replace the backup battery.
If the backup battery discharges quickly after replacement, replace the system board.
30
Hardware Maintenance Manual