Wednesday, June 01, 2016

Lenovo ThinkPad L450 – How to check the battery - How to measure the AC adapter voltage – How to check the backup battery

Category: Laptop Repair and Service 

Contents of this article 

  • How to measure the AC adapter
  • How to check the backup battery 
  • How to check the battery pack

Lenovo ThinkPad - L450

Power system checkout
To verify a symptom, do the following:
1. Turn off the computer.
2. Remove the battery pack.
3. Connect the ac adapter.
4. Check that power is supplied when you turn on the computer.
5. Turn off the computer.
6. Disconnect the ac adapter and install the charged battery pack.
7. Check that the battery pack supplies power when you turn on the computer.
If you suspect a power problem, see the appropriate one of the following power supply checkouts:
“Checking the AC adapter”
“Checking operational charging”
“Checking the battery pack”
“Checking the backup battery”
You are here because the computer fails only when the AC adapter is used.
# If the power problem occurs only when the ThinkPad Essential Port Replicator is used, replace the port replicator.
# If the power-on indicator does not turn on, check the power cord of the AC adapter for correct continuity and installation.

How to check the AC adapter Voltage 
To check the AC adapter, do the following:
1. Unplug the AC adapter cable from the computer.
2. Measure the output voltage at the plug of the AC adapter cable. See the following figure:
Note: Output voltage of pin no.2 of the AC adapter may different from the one you are servicing.
3. If the voltage is not correct, replace the AC adapter.
4. If the voltage is acceptable, do the following:
Replace the system board.
Note: Noise from the AC adapter does not always indicate a defect.
Checking operational charging
To check whether the battery charges properly during operation, use a discharged battery pack or a battery pack that has less than 50% of the total power remaining when installed in the computer. Perform operational charging. If the battery status indicator or icon does not turn on, remove the battery pack and let it return to room temperature. Reinstall the battery pack. If the charge indicator or icon still does not turn on, replace the battery pack.
If the charge indicator still does not turn on, replace the system board. Then reinstall the battery pack. If it is still not charged, go to the next section.

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
4. Remove the backup battery
5. Measure the voltage of the backup battery. See the following figure.
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.
Checking the battery pack
Battery charging does not start until the Power Meter shows that less than 95% of the total power remains; under this condition the battery pack can charge to 100% of its capacity. This protects the battery pack from being overcharged or from having a shortened life.
To check your battery, move your cursor to the Power Meter icon in the icon tray of the Windows taskbar and wait for a moment (but do not click), and the percentage of battery power remaining is displayed. To get detailed information about the battery, double-click the Power Meter icon.
Note: If the battery pack becomes hot, it may not be able to charge. Remove it from the computer and leave it at room temperature for a while. After it cools down, reinstall and recharge it.
To check the battery pack, do the following:
1. Power off the computer.
2. Remove the battery pack and measure the voltage between battery terminals 1 (+) and 7 (-). See the following figure:
3. If the voltage is less than +11.0 V dc, the battery pack has been discharged.
Note: Recharging will take at least 3 hours, even if the indicator does not turn on.
If the voltage is still less than +11.0 V dc after recharging, replace the battery.
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 . If the resistance is not correct, replace the battery pack. If the resistance is correct, replace the system board.