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4.0 Battery Pack Troubleshooting

We recently developed a desktop application that allows you to update your Battery Pack 4.0’s firmware, which will ensure it is functioning optimally. See How to Use the Battery Pack Updater for instructions to update your battery pack’s firmware before going through the following steps:


  1. Plug the battery pack into a power source using a USB-C cable and ensure either a red or green LED is displayed. Note that it may take 1-2 seconds for the LED to turn on.
  2. Check for a red or green LED display on the battery pack.
    • If no red or green LED displays on the battery pack while plugged in, try a different USB adapter or power outlet. 
  3. Wait 5-10 minutes.
  4. Place your WHOOP 4.0 on your wrist just as you would wear it day to day.
  5. With the battery pack still plugged in displaying a red or green LED, slide it overtop your WHOOP 4.0 and click it into place as you would charge.
  6. Wait 60 seconds.
  7. With the battery pack attached to the sensor and still plugged in displaying a red or green LED, gently lift up the 4.0 sensor from the side and look underneath where it rests against your skin.
  8. Check for green LEDs displayed underneath the sensor.
  9. If the green LEDs are on, unplug the battery pack from power but keep it attached to the sensor, and let it continue charging for 2 minutes.
  10. With the battery pack attached to the sensor, firmly double-tap the top of the battery pack. If it doesn't work the first time, try double-tapping 2-3 more times. The battery level indicator LED on the side of the 4.0 sensor should illuminate.

If you are still experiencing issues, please contact Membership Services via chat or by submitting a request. Please let us know which of the above steps did not work for you, since this will allow us to help more effectively.

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