Maintaining and replacing your backup battery for NBN Fibre Phone

The backup battery available for NBN™ Fibre to the Premises (FTTP) Power Supply Units, when fully charged, can allow an NBN™ Fibre Phone plugged into a UNI-V port on your Connection Box to work between 3 and 11 hours in the event of a power outage. Approximate usage is 5 hours.

iiNet no longer offers the option of a battery backup unit as of 30 August 2017.


  1. Make sure that your NBN™ Power Supply Unit is always plugged directly into an electrical outlet. Do not use an extension cord, double adapter, power board or any other kind of secondary plug.
  2. Unless you are going on an extended holiday, you should not turn off this electrical outlet. This will ensure the battery remains fully charged in case of a power outage.


  1. In the event of a power outage, the Power Supply Unit will beep once and automatically switch to its backup battery power.
  2. Once the battery charge has depleted to approximately 50%, the Power Supply Unit will beep four times in a minute (the Battery Power light will also flash) and then the unit will turn off to preserve power.
  3. To turn the Power Supply Unit back on after the battery has reached less than 50% charge, you’ll need to press and hold the BATTERY EMERGENCY USE button for two seconds, or until the unit beeps once and all 4 lights flash.
  4. Once activated, you cannot turn the BATTERY EMERGENCY USE off again. The remaining battery charge should last for a further 2 to 3 hours.
  5. If the battery runs completely flat, your Fibre Phone will not work again until power has been restored and/or the backup battery has been recharged.


A backup battery supplied by NBN Co has a 24 month warranty from day of first battery installation. You are responsible for sourcing, removing and installing the new battery.

If your battery does need replacing within the first 24 months, you will need to purchase a new battery that matches the specifications below and then supply the following to iiNet:

  • Tax invoice/receipt/remittance advice of the new battery
  • The serial number of the old battery (for NBN Co’s records)

We will then credit the cost of the battery to your account and request the reimbursement from NBN Co on your behalf. A battery typically costs between $40 to $60, though prices may vary. More details of where to source the battery and how to recycle it are available on the NBN Co website.


Battery Type: 12V 7.0-7.2Ah 6 Cell VRLA Sealed Lead Acid Battery

Dimensions: 94mm (H) x 151mm (W) x 65mm (D) (excl terminals)
100mm (H) x 151mm (W) x 65mm (D) (incl terminals) (all tolerances +/- 1mm)

Terminal Type: Spade-type. Quick disconnect ‘F2’ 6.35mm (W) x 0.81mm (Thickness)


  1. Turn off the electrical outlet for the Power Supply Unit and then unplug the power cord from the electrical outlet.
  2. Open the front cover of the Power Supply Unit.
  3. Disconnect the red positive (+) plug from the battery.
  4. Push the tabs above and below the battery outward, and then lift the battery out of the Power Supply Unit.
  5. Disconnect the black negative () plug and remove the battery.


  1. Connect the black negative () plug to the new battery.
  2. Push the battery retaining tabs outward and insert the battery into the Power Supply Unit.
  3. Connect the red positive (+) plug to the new battery.
  4. Make sure the wires are not being pinched by the battery or the front cover.
  5. Close the front cover and plug the Power Supply back into the electrical outlet and turn the power on.
  6. The new battery will take 24 hours to completely charge. Please keep the old battery as a backup unless it no longer functions.
  7. Once power is returned to your NBN™ equipment, please allow up to 10 minutes for it to reboot. During this time, you may not be able to use your NBN™ services.