Each F21 sensor uses 2 D-Cell lithium metal batteries which last 18-24 months in standard retail environments. Each F20 sensor uses 4 AA lithium metal batteries. If you believe your sensor’s batteries are dead, contact Dor support to order new batteries.


Once the batteries arrive, follow the instructions below to replace them.

F21 Sensor

F21 sensor
  1. Remove the sensor from the mounting plate by pulling away from the door.

  2. Press the white button on the bottom of the sensor. This will minimize data loss by relaying any stored data to the server.

  3. Remove the old batteries from the sensor.
    Please properly dispose of the non-rechargeable lithium batteries at a battery recycling facility. Do not dispose of lithium batteries in the trash. Battery recycling facilities can be found at www.call2recycle.org or by calling 1-877-2-RECYCLE

  4. Put the new batteries in the sensor, being sure to pay attention to the +/- orientation. The sensor will chime as it boots up.

  5. Place the sensor back on the mount.

  6. Confirm the sensor is connected by viewing the Device Status page of the Location’s page.

F20 Sensor

F20 sensor
  1. Remove the sensor from the mounting plate by sliding it away from the door.

  2. Press the red button on the back of the sensor. This will minimize data loss by relaying any stored data to the server.

  3. Remove the old batteries from the sensor.
    Please properly dispose of the non-rechargeable lithium batteries at a battery recycling facility. Do not dispose of lithium batteries in the trash. Battery recycling facilities can be found at www.call2recycle.org or by calling 1-877-2-RECYCLE

  4. Put the new batteries in the sensor, being sure to pay attention to the +/- orientation.

  5. Place the sensor back on the mount.

  6. Confirm the sensor is connected in the Device Status page of the Location’s page.

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