Security Advice · Ajax Alarms
Do Ajax Alarms Work Without WiFi or Power?
The honest answer is yes, and the reason why matters more than the yes does – because the night you lose power is usually the night you also lose the internet.
The short answer
- Power cut: the hub runs on internal battery for up to 16 hours.
- Internet down: the built-in SIM takes over automatically, with no action from you.
- Both at once: this is the case Ajax is actually designed for, and it is the normal case in a storm.
- Jamming: the hub changes frequency automatically rather than going quiet.
- Detectors run on their own batteries measured in years, so they are unaffected by mains power either way.
Why this is the right question to ask
Most alarm marketing answers the two failures separately: battery backup on one line, cellular backup on another. In practice they are not independent events. The Auckland storm that takes your power out very often takes the fibre or the modem with it, and that is precisely the night a property is worth breaking into.
So the question is not “does it have a battery” or “does it have a SIM”. It is whether it has both, and whether the switch between them needs you to do anything. A hub with battery backup but no cellular path is still offline. A hub with cellular but no battery is still dead.
What happens in a power cut
The Ajax Hub 2 Plus carries an internal battery giving up to 16 hours of running time. During an outage the system stays armed, the detectors keep reporting, the app keeps working and any monitoring connection stays alive.
The detectors themselves were never on mains power in the first place. Ajax wireless devices run on their own batteries with life measured in years, and the app tells you well before one needs replacing. A power cut simply does not reach them.
Sixteen hours covers the overwhelming majority of New Zealand outages. For sites where a longer outage is a real risk – rural properties, or commercial premises with a compliance requirement – that is a conversation to have at quote stage, not afterwards.
What happens when the internet drops
The hub has a SIM card built in. If the broadband path fails, it moves to cellular automatically. You do not open the app, flip a setting or get a prompt – alerts and the monitoring link simply keep working over the mobile network.
This is also why an Ajax system does not depend on your router being healthy. A modem that has locked up, a fibre fault down the street, or an ISP outage are all the same event as far as the hub is concerned: a path failed, use the other one.
Worth knowing: because the hub can reach the network on its own, an Ajax system will keep alerting you at a property with no broadband at all – a bach, a shed, a site between tenancies.
It is one of the more common reasons people move to Ajax alarms in Auckland from an older panel that needed a phone line.
What about jamming?
A fair question for any wireless system, and the honest concern with cheap ones. An unprotected radio alarm that gets jammed goes quiet, and quiet looks identical to “nothing is happening”.
Ajax hubs detect interference and switch frequency automatically. Jamming is treated as an event in its own right rather than as silence, so the system tells you it is being interfered with instead of simply failing to speak.
Communication between every device and the hub is encrypted in both directions, which is a different problem from jamming but the same underlying design principle: assume someone is trying.
Where the limits actually are
We would rather set expectations properly than sell certainty that does not exist.
- Sixteen hours is not indefinite. A multi-day regional outage will outlast the hub battery. If that is a genuine risk for your site, say so at quote stage.
- Cellular needs coverage. The failover is only as good as the mobile signal at the hub’s location, which is one of the things we check on the site visit rather than assume.
- Cameras are a separate question. An alarm keeping working through an outage does not mean an NVR and cameras are – those have their own power requirements.
- Sirens still need the property to be occupied nearby to matter. If nobody hears them, the value is in the alert and the response, not the noise.
Common questions
Does an Ajax alarm need WiFi?
No. It can run entirely on its built-in SIM, so it works at properties with no broadband at all. Where WiFi or ethernet is available the hub will use it and keep cellular as automatic backup.
How long does the Ajax hub battery last in a power cut?
Up to 16 hours of internal battery on the Hub 2 Plus. Detectors are unaffected – they run on their own batteries with life measured in years.
Will I still get alerts if my internet goes down?
Yes. The hub switches to cellular automatically and keeps sending alerts and maintaining any monitoring connection. You do not need to do anything.
What happens if someone tries to jam the signal?
The hub detects the interference and changes frequency automatically, and reports the jamming attempt as an event rather than simply going quiet.
Do the detectors need power?
Not mains power. Ajax wireless detectors run on their own batteries, typically for years, and the app warns you well before one needs changing. Fibra wired detectors are powered through the cable instead.
Does it still work if I unplug the router?
Yes – that is functionally the same as an internet outage, and the hub moves to cellular on its own.
Want it to keep working on the worst night of the year?
We check cellular signal at the hub location as part of the site visit, not after the install. Free assessment, written quote.