1) ThinkPad Edge E220s, ThinkPad Edge E420s, and ThinkPad X1 Main Batteries:

• Battery Full Charge Capacity may be incorrect, slightly reducing the battery run time available (about 5-10%).

2) ThinkPad X1 Slice Battery:

• Battery won't charge
• In some cases, the X1 system won't boot with the Slice battery attached, and the customer may need to press the power reset switch through the access on the X1 bottom cover to recover.
• Power Manager shows:
  • Second Battery Condition is Poor
  • Message: "A battery error has occurred. The battery cannot be charged. Replace the battery."
    
    

The following Lenovo ThinkPad systems:

• Edge E220s (Machine Type : 5038)
• Edge E420s (Machine Type: 4401)
• X1  (Machine Type: T 1286, 1291, 1292, 1293, 1294, 1295, and 1296)
• Slice battery option for X1

Battery Firmware (FW) updates are available and recommended to prevent the symptoms described above.
Click here to download the Battery FW Update Utility.

Note:
After the Battery Firmware update has completed, the battery fuel gauge (Power Manager) may temporarily show an incorrect value (0% or a low %). The gauge will reset and work correctly after fully charging the battery to 100%.

Special Instructions for X1 Slice battery that is already showing the Battery Error symptom above:
The FW update may still be applied and will in most cases reset the battery error. In this case, please do the following:

1. If the X1 system hangs at power on (i.e., won't boot), disconnect the AC Adapter, remove the Slice battery, and press the Power Reset switch through the access hole in the X1 bottom cover.
2. Shutdown (Power Off) the X1 system.
3. Attach the Slice Battery and slide the latch to lock it.
4. Important: Connect AC Adapter before powering on.
5. Power On the X1 system with AC Adapter and Slice Battery attached.
6. Launch the Battery FW update utility and follow the instructions on the screen.