Door sensors for METAL gate

Hi, I have many xiaomi door sensors which work very well, reporting also the sensor state. Unfortunaltely on a gate, totally made of metal, they do not work.

This particular gate sometimes is not closed well by members of the family and I wish to have an automation that notifies when they gate is ON for over X minutes

ANy suggestions for a door sensor that would work? I guess I meed those 433Mhz sensors, but I do need they report also the state, or any other ideas?

If the metal gate is causing issues for the reed switch, how about using a limit switch? However it seems strange you are having issues as I’ve used reed switches on metal doors / gates in the past. Are you sure that the sensor and magnet are correctly aligned?

haven’t tested much, it simply didn’t trigger, in the xiaomi instructions is clearly written they do not work on metal surface: so I don’t know its the reed or the Zigbee signal.

I thought it is the zigbee signal, but I am not sure, so I bought a month ago my first 433MHz switch, but they didn’t arrive yet (the door keeps beeing left open lol)

There’s two problems with using reed switches on ferromagnetic metal surfaces:

  1. the magnet can cause the metal under the reed switch to magnetise and trip the switch permanently.
  2. the metal can shunt the majority of the field lines away from the switch and the reed switch may not activate.

One solution is to mount the magnet and reed switch on wooden blocks 15-30mm thick. Ugly indoors but on a gate won’t be that noticeable.

Otherwise I’ve used the ME-8166 limit switch with great success:

I also tried the ME-8122, this did not work well at all.

Also the ones I linked to are cheap knock offs. They’re about a 25th of the price though. Liberal application of silicone grease should aid in life expectancy:

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What is the method to integrate them into HA (if they are…)?

Cool solution for my other door I have in the garden.
I was thinking that there should be a material to stick under the sensor, that is thinner then 3cm wood (and not so invasive) , to avoid magnetization of the door,

Any idea?

Something like this maybe (NOT in yellow colour, lol)

https://hivis.com/commercial/mining/magnetic-reflective-tapes/

That is optically reflective material with a magnetic backing. It will interfere with your reed switch.

There really isn’t a diamagnetic material that is physically suitable.

MQTT over wifi using ESPhome. I use an ESP32 module as it is better at sleep / wake than the ESP2866 and so can be solar powered more easily. The module only wakes for a couple of minutes on a change of state of the switch or every 12 hours. I have an automation that lets me know if I have not heard from it in 14 hours and a battery level. monitor. So far a protected 2200mAh 18650 + 3W 6V PV panel (with a 4.2V regulator) has been holding the battery rock steady at 4.16V. Got the same thing on my mailbox.

interesting. thanks. I thought I saw a PV panel beside the switch and was wondering if that was the supply.

More info on the parts here:

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not sure if the problem is the Zigbee signal (that has interference near a metal gate) or the magnets for the reed switch that magnetize the door. Today finally arrived 433MHz door sensors (also made with reed switch) I will try those now and report if they work or not.

If not will have to look at limit switch. Any link for Zigbee or 433MHz limit switch (battery operated)?