Keeping the NBN on in a blackout: what a power station can and can't do

Whether a power station keeps your NBN on in a blackout depends mostly on how your place is connected. If you're on fibre to the premises (FTTP), the network side usually keeps working, so running the nbn connection box and your modem from a power station keeps you online for as long as the battery lasts. On fibre to the node, curb or building, cable (HFC) and fixed wireless, nbn says the service drops if the network equipment loses power too, and a battery at your place can't fix that. We'd still set one up, because plenty of outages are only on your side of the street.

The network details here come from nbn's own blackout pages and its fibre user guide. Station figures come from the makers' Australian pages, and the runtimes are our sums, not measurements.

Why the NBN needs power at both ends

The old copper phone line was powered from the exchange, so a plain corded phone kept working in a blackout. nbn says the NBN needs power at the exchange end and inside your home, and it can't guarantee both at all times. That's why every type of landline phone, corded or cordless, stops in an outage unless something keeps your gear powered.

It also means every mains-powered device in the chain needs its own backup. nbn lists the modem, the Wi-Fi router, cordless phones and computers. If your phone plugs into the router, the router has to stay on for calls to work.

Check your connection type first

nbn's wording for node, curb, building and cable is the same each time: the service won't work if there's a power outage in that part of the network or in your home, and restoring power at your end with an alternative supply isn't possible when the network is also down. For fixed wireless it says the same of the tower. If you don't know which you have, your provider can tell you. A big white nbn box on the wall with a fibre lead going into it is usually FTTP, while on FTTN and FTTB there's no nbn box at all and the modem plugs into the phone socket.

nbn's 2023 notice withdrawing its battery backup product spells out the reason. On curb and cable, the equipment at your place relies on powered network gear nearby, so a battery in your home doesn't guarantee the service stays up.

What the old nbn battery did

Some FTTP homes still have nbn's power supply with a battery backup. nbn stopped offering it in June 2024, though your provider may be able to arrange one. According to the fibre user guide, it powers the connection box only, for about five hours. At around 40% charge, after 3 to 3.5 hours, it shuts off to save the rest, and pressing the emergency reserve button gives roughly another 1.5 to 2 hours.

That was built for one thing: a corded phone plugged into the box's voice port. It never ran your modem or Wi-Fi router, so on most setups the internet still dropped the moment the power did.

Running the NBN from a power station

The setup is the same on every connection type. Plug the station into its usual power point, then plug the nbn box's power supply (if you have one) and the modem's plug pack straight into the station's AC outlets. Leave them there. When the grid drops, a station with a UPS function switches the outlets to battery.

The switchover time matters, because any gap long enough to cut the power makes the modem restart and reconnect. EcoFlow lists under 10ms for the EcoFlow RIVER 3 Plus and within 10ms for the EcoFlow DELTA 3 Plus. Bluetti lists 10ms or less for the Bluetti Elite 30 V2, and Anker lists under 20ms for the Anker SOLIX C1000. EcoFlow pitches its 10ms switchover at desktop computers and NAS drives. A station without a listed switchover time may still do pass-through, but don't count on the internet staying up without a blink.

Energex says that, unlike a UPS, a portable power station doesn't switch on automatically in an outage and has to be connected manually. That's true of a station sitting on a shelf, and it's why the makers' UPS figures above only apply in this pass-through setup, with the station already plugged in and your gear running through it.

That raises a safety catch. The Queensland Fire Department's advice for lithium batteries is to charge when you're home, never leave them charging unattended, and disconnect once they're full. A station sitting in pass-through mode is on charge the whole time, so we'd only run it that way when a storm's forecast and someone's home, then unplug it from the wall once the weather clears. Put it on a hard, non-combustible surface like tiles or concrete, in a ventilated spot away from curtains, bedding and anything that could block an exit. Don't charge or use it if it's hot, swollen or damaged, and don't chain powerboards off each other to reach it.

Never plug the station into a power point or switchboard to feed the house wiring. Energex warns that backup power fed in through a power point can flow back into the network and give life-threatening shocks to you, your neighbours and the crews fixing the lines. Our guide to changeover switches covers the only safe way to back up house circuits.

How long it lasts

Check the labels on your own gear, since the rating on a plug pack is a maximum. For the sums we'll assume the nbn box and modem together average 20W, and allow 15% for conversion losses, which is also our assumption.

The RIVER 3 Plus has 286Wh, according to EcoFlow. That's 286 x 0.85 = 243Wh, and 243 / 20 = about 12 hours. The Elite 30 V2's 288Wh works out the same. The DELTA 3 Plus has 1,024Wh, so 1,024 x 0.85 = 870Wh, and 870 / 20 = about 43 hours, before you charge anything else from it.

Small loads are where the 15% guess is shakiest. Bluetti quotes a standby draw of 4.5W for the Elite 30 V2's inverter, which on a 20W load is a big share. Switching the modem off while you sleep stretches a small station further than any other trick. If you also want the fridge and lights, start from our cyclone season sizing guide, and the runtime calculator takes your own numbers.

Keep a plan B

nbn's advice for every connection type is to keep a charged mobile phone handy, and its emergency fact sheet adds a portable battery pack to the kit. On node, curb, cable and fixed wireless that phone is your real backup. In a fixed wireless or satellite area, nbn says you may be able to keep your existing copper landline, which is worth asking your provider about if mobile coverage at your place is patchy. Renters can do all of this without touching the wiring, as our renters' blackout plan explains.

Quick questions

Will my monitored medical alarm work over the NBN in a blackout?

Don't assume it will. nbn says to ask the alarm's provider whether it works over the network in a power outage, and it requires battery backup for Priority Assistance customers. Ask your phone and internet provider about that too.