Motion Sensor with Battery that Lasts for Years?

Other Hardware General Electronics
1

I was reading about the alarm system company SimpliSafe, and they claim that the batteries in their sensors (motion sensors, glass break sensors, door contacts) last for years on a single battery.

How is this possible? Wouldn't the sensor need to be constantly running? And it would have to have either Wifi or some other strong radio to communicate with its base station which could be on a completely different floor of the house.

What am I missing here?

Thanks!

2

The sensor is in deep sleep, drawing negligible power, until some event wakes it up to sound the alarm.

Here is an excellent tutorial on power saving with Arduino.

3

glass break sensors, door contacts

These are simple brake in continuity sensors and can use a very very tiny current .
The motion sensor is a lot harder to understand.
If they are wireless then the transmitter will only be on once the alarm has been triggered. This keeps the average current down.

4

Think about smoke detectors. Same smell. Or even wristwatches that have moving parts lasting for many years on tiny tiny batteries.

5

Thanks guys!

Continuing the theoretical discussion about how Simplisafe has potentially designed this motion sensor: if it's supposed to last for years, I doubt they'd be able to constantly send a notification to the base station every time it detected motion. In a normal house, it would constantly be transmitting. What if the base station tells the circuit when its armed or not, and when it's not, it doesn't transmit when it detects motion, it stays asleep. It wakes up only for new commands from the base station.

What does everyone think?

6

What if the base station tells the circuit when its armed or not, and when it's not, it doesn't transmit when it detects motion,

Yes that would do it.

7

The PIR motion sensors i have last around 3 years on a single battery. When the detect motion they "waken up" and squirt out a signal to the alarm box then go to inhibit for a few minutes to prevent continuous sensing.

Obviously if the room is continuousy occupied then the battery use is heavier.

Installation of alarm sense devices should look at peripheral zone boundaries which are crossed by entry or exit to an area rather than places of continuous occupation. That way the sensor spends the vast majority of its life asleep.