Checking The Coin-Cell Battery - Lenovo ThinkPad P52 Hardware Maintenance Manual

3. 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.
4. Depending on the voltage that you measure, do one of the following:
• If the voltage is less than +11.0 V dc, recharge the battery pack. If the voltage is still less than +11.0 V
dc after recharging, replace the battery pack.
• If the voltage is more than +11.0 V dc, discharge the battery pack until the voltage becomes less than
+11.0 V dc and then recharge the battery pack. If the voltage still is less than +11.0 V dc after
recharging, replace the battery pack.
Note: Recharging will take at least three hours, even if the battery status indicator does not turn on.
5. Replace the system board if the new battery pack is not charged.

Checking the coin-cell battery

To check the coin-cell battery, do the following:
1. Remove the battery pack. See "1010 Battery" on page 71.
2. Remove the coin-cell battery. See "1050 Coin-cell battery" on page 74.
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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ThinkPad P52 Hardware Maintenance Manual
Wire Voltage (V dc)
Red +2.5 to +3.2
Black Ground