Battery Backup Unit

Battery Backup Unit

What is my Battery Backup Unit (BBU)?

Your Optical Network Terminal is installed with a separate Battery Backup Unit (BBU). When a fully charged 12-volt battery is installed in the BBU, you will have up to 8 hours of backup power for basic voice service, including calls to 911.

Internet and TV service will not be available during a power outage even if a fully charged battery is installed.

  • BBU audible alarms and buttons
  • Audible alarms
    An alarm will sound once a minute to alert you if the battery it is not fully charged or has been drained completely. This will be repeated until you press the Alarm Silence button.

    Don't need the BBU and want to silence the beeping for good?
    Most Fios ONTs will operate without the presence of a backup battery. If you do not have landline voice service through Verizon, or if you do not need your fiber voice service during a power outage, you can safely and easily disconnect the backup battery from your Fios ONT to ensure the battery alarm will remain silent. To do this, unplug the battery backup unit from the wall outlet and disconnect the battery.

    Alarm Silence. Press to silence the audible alarm.
    Battery Emergency Use. Press once to reboot the ONT and get up to 1 hour of battery life for emergency phone calls. Once pushed, all remaining battery life will be used.
    Battery lights
    Spacer Gif! Auxiliary Power Source
    GREEN - auxiliary power available
    RED - auxiliary power not available
    Replace Battery
    RED - battery needs to be replaced
    Battery Power
    RED - ONT is operating off battery power; no commercial power available
    BLINKING RED - low battery power
    System Status
    GREEN - normal operation
    BLINKING GREEN - system fault

  • Purchasing a new 12-volt battery
  • 12 volt 7.2Ah sealed lead acid batteryOnly 12-volt 7.2Ah sealed lead acid batteries should be used in the BBU. Batteries should be purchased just prior to replacement as 12-volt batteries may not maintain their shelf life when stored.

    You can purchase a new battery from Verizon by visiting or you may purchase one from a third-party vendor. If you choose to purchase your replacement battery from a third-party vendor, please make sure that you are purchasing a 12-volt 7.2Ah SLA (Sealed Lead Acid) battery.

  • Accessing Your Battery
  • If you are having trouble accessing your battery, click here for detailed information for your specific device.

  • Battery disposal information
  • When replacing your battery, please make sure to dispose of your old battery properly. For more information about recycling, you can contact Call2Recycle at 1.877.RECYCLE (1.877.273.2925) or visit to find a list of the drop-off locations closest to you. You may also visit or call the EPA at 202.272.0167 for instructions. Your local municipality may also have information about proper disposal of batteries.

    Power and battery information is also available at in Spanish, Chinese, Korean and Vietnamese.

  • Monitoring and maintaining the battery in your BBU
  • You are responsible for monitoring and maintaining your backup battery. Battery age, usage and temperature will impact battery life and performance so reducing the amount of time the batteries remain stored and unused is recommended.

    Only 12-volt 7.2Ah sealed lead acid batteries should be used in the BBU. Batteries should be purchased just prior to replacement as12-volt batteries may not maintain their shelf life when stored.


     Disconnecting and replacing the battery in your BBU

    1. Unplug the BBU from your wall outlet. Then open the battery compartment.
      If you are having trouble accessing your battery, click here for detailed information on accessing your battery.
    2. Remove the plug connector with the red and black cables by pinching and sliding it out of its location.
    3. Gently disengage the retaining clips that hold the battery in place and remove the battery.
    4. Disconnect the battery clips from the old battery and set the battery aside to properly dispose of. If you are not installing a new battery, proceed to Step 8. Save the red and black cable for future use.
    5. Remove the plastic covers on the black and red terminals of your new battery. Connect the battery clips to the corresponding black (- negative) and red (+ positive) terminals on the new battery.
    6. Slide the new battery into the battery compartment, securing it underneath the retaining clips.
    7. Insert the plug connector back into position. If the battery is installed correctly, you'll hear a beep and the battery power and system status lights will be solid green.
    8. Replace the battery cover and plug the BBU back into your wall outlet.
  • how to replace the battery in a BBU

To better assist you with disconnecting and installing new batteries in your BBU, we've created a simple two minute video that can walk you through each step. Click on the video below to start watching.

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