Lenovo ThinkPad X301 Hardware Maintenance Manual page 62

5. Measure the voltage of the backup battery. See the following figure.
v If the voltage is correct, replace the system board.
v If the voltage is not correct, replace the backup battery.
v If the backup battery discharges quickly after replacement, replace the system
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ThinkPad X301 Hardware Maintenance Manual
Red (+)
Black (-)
board.
Wire Voltage (V dc)
Red +2.5 to +3.2
Black Ground