Lenovo ThinkPad A21m Hardware Maintenance Manual for ThinkPad A21e (2628) - Page 36

Checking the backup battery, for Nickel metal hydride battery

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Checkout guide for Nickel metal hydride battery; v If the voltage is more than +8.0 V dc, measure the resistance between battery terminals 4 and 5. The resistance must be 4 to 30 K ohm. 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 adapter from it. 2. Turn the computer upside down. 3. Remove the battery pack (see "1010 Battery pack" on page 51). 4. Remove the backup battery (see "Checking the battery pack" on page 31). 5. Measure the voltage of the backup battery. See the following figure. Wire Red Black Voltage (V dc) +2.5 to +3.2 Ground 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 board. 32 ThinkPad A21e

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for Nickel metal hydride battery;
v
If the voltage is more than +8.0 V dc, measure the
resistance between battery terminals 4 and 5. The
resistance must be 4 to 30 K ohm.
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 adapter
from it.
2.
Turn the computer upside down.
3.
Remove the battery pack (see “1010 Battery pack” on
page 51).
4.
Remove the backup battery (see “Checking the battery
pack” on page 31).
5.
Measure the voltage of the backup battery. See the
following figure.
Wire
Voltage (V dc)
Red
+2.5 to +3.2
Black
Ground
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 board.
Checkout guide
32
ThinkPad A21e