Everything you need to know about an NBN backup battery

Fibre-to-the-Premises (FTTP) is the broadband connection technology that keeps giving. It’s the most future-proofed form of internet in Australia that lets you sign up to gigabit internet plans. For homes without it, FTTP is the only upgrade option. And for homes that do have FTTP, it also has a neat battery backup option.

NBN backup batteries offer a few hours of extra power in the event of a power outage, exclusively for FTTP homes that opted to have them installed. While that sounds great on paper, don’t expect to be able to use your internet during a power outage unless your router has its own battery backup. Still, the extra battery life does mean you can use a connected landline phone service during a power outage (if you have one with your NBN plan).

For reference, below is a list of cheap NBN plans from our comparison engine that include a landline phone service.

There are two parts to this answer. For starters, an NBN backup battery can technically last up to five hours during a power outage. The disclaimer there is it will automatically turn off when it hits 40% remaining battery life, which is after about 3.5 hours. You can override this by pressing the ‘emergency reserve’ button and you should be back for the remaining 1.5-ish hours after a few minutes. This can be extended by connecting an uninterruptable power supply that has a 230V 50Hz AC waveform.

As for how long the NBN backup battery lasts in terms of its overall longevity, NBN Co reckons battery life will get around 70% of full capacity after 3.5 years (around 3.5 hours per full charge). Keep an ear out for beeping, which means it’s time to replace (with four beeps per minute indicating 50% overall capacity, or around 2.5 hours per full charge).

NBN backup batteries are sensitive to extreme temperatures. Try to keep yours clear of extreme cold (anything below -1 degree Celsius) to stop it from draining faster. Similarly, NBN backup batteries can age faster if they’re kept warmer than room temperature (approximately 20 degrees Celsius). NBN Co also recommends against frequently powering the NBN backup battery on and off, which could cut 1.5 years off that 70%-of-full-capacity battery life. Finally, keep an ear out for audible alarms and check the battery indicator for any problems, plus replace the NBN backup battery if advised by your provider.

The first NBN backup battery that comes as part of signing up for an NBN plan for the first time should be free of charge. Speak with your provider about potential costs involved. When it comes time to replace an NBN backup battery, though, the cost is on you. Chat with your provider to see if they can provide a replacement or whether you should source your own. Costs vary depending on where you buy one from, but expect to pay at least $70 for an NBN backup replacement battery.

NBN Co offers a list of specialist battery retailers by state or territory, but you can also just refer to the table below. Note that this table also lists battery retailers that offer in-home replacements and/or battery recycling.

Alternatively, if you want to try your hand at sourcing an NBN backup battery replacement from a retailer not listed in the table above, you’ll need a battery that meets the key specifications outlined in the table below.

Follow these steps to disconnect an NBN backup battery, but first read through the NBN Co FTTP connection box guide (PDF) and consider enlisting professional help if you’re uncertain:

1. Switch off and disconnect the Power Supply with Battery Backup from your home’s mains electricity.
2. Open the cover of the Power Supply with Battery Backup, which houses the battery itself.
3. Disconnect the red positive (marked ‘+’) plug from the NBN battery.
4. Identify the tabs above and below the NBN battery, then push them outward.
5. Lift out the NBN battery, then disconnect the black negative (marked ‘-’) plug from the NBN battery.
6. The NBN battery is now able to be fully removed and can be disposed of.

If you’ve opted to replace the NBN backup battery yourself, again, it’s worth familiarising yourself with the NBN Co FTTP connection box guide PDF linked above before proceeding. After that, if you haven’t chosen a battery retailer that installs it for you, here are the steps to follow to install a replacement NBN backup battery:

1. Ensure the power to the Power Supply with Battery Backup is disconnected from the wall outlet.
2. Open the cover of the Power Supply with Battery Backup, then connect the black negative (marked ‘-’) plug to the replacement NBN battery.
3. Insert the replacement battery into the Power Supply with Battery Backup by pushing the battery retaining tabs outwards.
4. Connect the red positive (marked ‘+’) plug to the replacement NBN battery.
5. Close the cover of the Power Supply with Battery Backup, keeping an eye on any wires that may get pinched by the cover.
6. Reconnect the power cable to the Power Supply with Battery Backup, then flick it on.
7. Wait 10 minutes for your FTTP connection and landline phone service to return and 24 hours for the replacement NBN backup battery to fully charge.