Checking The Coin-Cell Battery - Lenovo ThinkPad T450 Hardware Maintenance Manual

2. Remove the external battery pack and measure the voltage between battery terminals 1 (+) and 7
(-). See the following figure:
1(+)
3. If the voltage is less than +11.0 V dc, the external battery pack has been discharged.
If the voltage is still less than +11.0 V dc after recharging, replace the external battery pack.
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 external battery pack. If the
resistance is correct, replace the system board.
Checking the operational charging
To check whether the battery pack charges properly during operation, do the following:
1. Discharge the battery pack until the remained battery power is less than 50%.
2. Connect the computer to ac power to charge the battery pack. If the battery status icon in the Windows
notification area indicates that the battery pack is not charging, remove the battery pack and let it
return to room temperature.
3. Reinstall the battery pack. If the battery pack is still not charging, replace the battery pack.
4. Check the battery status icon again. If the same error still exists, replace the system board.

Checking the coin-cell battery

To check the coin-cell battery, do the following:
1. Disable the internal battery pack. See "Disabling the internal battery pack" on page 60.
2. Remove the coin-cell battery. See "" on page .
3. Measure the voltage of the coin-cell battery. See the following illustration.
• If the voltage is correct, replace the system board.
• If the voltage is not correct, replace the coin-cell battery.
• If the coin-cell battery discharges quickly after replacement, replace the system board.
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Hardware Maintenance Manual
7(-)
6(-)
5
3 4
2(+)
Terminal Voltage (V dc)
1, 2 + 0 to + 12.6
6, 7 Ground (-)
Wire Voltage (V dc)
Red +2.5 to +3.2
Black
Ground