Wireless Outdoor Siren

Hardware
1

Hi, I’m searching a great solution to a problem that literally blow my mind. I have already spent many hours without even a feasible idea.
I need/would a Wireless Outdoor Siren that can work with Home Assistant, not just a chinese toy but something that worth, with batteries that last at least 1 year.

I searched on internet as much as possible, but I’ve just found one device
https://community.home-assistant.io/t/outdoor-zigbee-siren-smabit-bitron-video-av2010-29a/284993
with conflicting reviews and however not sold anymore.

I discovered different devices for commercial systems instead. For example Hikvision DS-PSG-WO-868, Hikvision DS-PS1-E-WE, Veho Cave VHS-006-OS, … that promise to last also 3-4 years. I would buy them even if they are expensive but I believe that I can’t make them communicate with Home Assistant. But if I’m wrong please tell me!

So I decided to study further, I’m new in smart home subject, and I thought to use an ESP8266 (e.g. Wemos D1 Mini or similar), as suggested in DIY projects founded online. The idea is (or was) about drive a standard Wired Outdoor Siren (but without wires), with an ESP8266 (posed inside the siren’s box) that control a SPST relay, which closed let current flow from batteries to siren (probably through a voltage step-up regulator).
The main problem lays in current consumption. Reading I found that ESP8266 could use 72mA-80mA with wifi-on and just 0.17mA in deep-sleep, but also that need about 5 seconds to reconnect after deep-sleep.
So also if I decide to make sleep ESP for 60 seconds, I get (80x5+0.17x60)/65 with a mean consumption of 6.3mA, that with 8000mAh (I assume to use three alkaline D batteries up to 67%) brings to just 53 days, not even close to 1 year and neither to 6 mounth.

How can commercial systems declare 3-4 years? Probably some use RF and others wi-fi, but however I can’t find RF module with lowest current consumption.

What can I do? Do you know commercial siren that can be controlled by Home Assistant? Have you got better ideas?

2

A high quality RF receiver module with channel monitoring uses in the µA range.

The thing is, if you want a low power application where you run on a battery for years and you want it to be on constant reception, then forget about wifi. Specific low power protocols like Zigbee or Zwave come to mind, but they’re harder to DIY. Simple RF on any of the ISM bands is another option (but you need to design the protocol).

In a real low power application, your main MCU is on almost permanent deep sleep or even unpowered. A separate low power RF processing system will monitor your RF channel and wake up the MCU and the transmitter (or power them on) only when receiving something that looks like a valid signal signature for your protocol. Something like this module for example. It consumes 10µA during monitoring. Different approaches are possible, but designing very low power devices is challenging and requires quite some experience.

1 Like
3

Nice tip. Thanks.
That module (10µA) seems complicated to make work and even to get, but I searched and found more commercial/generical objects like these. Maybe I could drive transmitter with Raspberry GPIO (that I believe could use with Home Assistant), than receiver could wake up the deep-sleepy esp8266 that will check/verify that Home Assistant is firing instruction, than… It’s another step and 2 more objects (cheap/poor quality) are needed…

It would be easier (and clear) if there was an extra small zigbee-relay (low voltage, low current) or even a simple zigbee module (could be based on esp32-h2 in the near future?), but I can’t find nothing now.