So after reading some other users posts about Diy Zigbee sensors using the aqara door/window sensors I started thinking about what else I could do with one. Initially nothing crossed my mind until the water top of tank for my wife’s fish tank ran dry leading to the pump running dry for who knows how long. I then remembered that the cheap water level float sensors use two wires just like the diy sensors I had read about. I quickly ordered the parts on aliexpress and promptly forgot about my idea until they showed up. This weekend I got around to wiring one up and am happy to report it works exactly as I hoped. Below I will do my best to walk through how I did it. I will try and include some photos I took as well.
-1 aqara door/window sensor
-1 water float switch (2PCS Tank Pool Water Level Liquid Sensor Ball Float Switch Connectors Switches | eBay) - may not be the cheapest price but any sensor with two wires should work.
Pry open the aqara sensor with tweezers or a small flathead screw driver, and pop out the chip.
Locate the reed switch, it is the tiny glass tube.
You will notice it is soldered on both ends, our goal is to connect one wire to the pad on either end of the reed switch. Doesn’t matter which wire goes where.
It will function if you leave the reed switch in place. Before I knew it would work I soldered the wires in, leaving the switch there. But once I knew it would work I snipped it off. Once you solder the wires on it should look like this:
Notice how the wires are pointing one direction, that was intentional and will be helpful when putting the chip back in the case. Also notice that I am not all that great with a soldering iron:)
Notch out the corner of the case to allow the wires to pass through. a sharp pair of snips did the job.
Reassemble the sensor.
At this point you have two options. When disassembling the sensor I snapped of the interior piece that held the chip in place. This also apparently is what allowed the top portion of the case to snap shut. So now when I placed the top part on it didn’t stay put. I solved this with a piece of scotch tape. Alternatively you could try and leave that interior piece in place and see if the wires would fit inside with it there. I have not yet opened up another sensor to test if it would fit.
Here is the finished project:
At that point I simply paired it with Deconz and added it to HA. I THINK ( I am not sure) which position it reads on or off for will depend how you connected the wires. So just bench test it to see if on or off in HA corresponds to a low water level. I then set up a automation to notify me when the water in the tank got below about 1/4. I plan to add a smart outlet on the socket for the pump so I can also kill power to the pump automatically.
This is the first time I have ever tried sharing a walkthrough like this so place let me know if you I missed something or if you have questions. Also if you know of another sensor that runs on two wires let me know and possibly I will try it out.