Safe & Warm - mattress heating pad idea

Anyone else using low-voltage "Safe & Warm" mattress heating pad or blanket? Interest in making it smarter?

We are replacing our beloved mattress heating pad after a decade or so of service. I was already playing around with a design add some ZigBee smarts, but I will wait until I confirm that the new controller has the same fit/form/function.

The existing controller has an on/off button and dial (LO, 1-10, HI). It has a 10-hour turn off timer and some basic current sensing in that it turns off if no load is connected. There is a photocell, but I never really noticed it having an affect on LED intensity. The real selling points are low-voltage (16-18Vdc) and very thin heating wires.

The design that I am entertaining:

  • INA226 to read voltage and current and real-time Alert output
  • High side PFET switch to better sense short to ground
  • CC2530 module for ZigBee (built on MonaLisa firmware & driver)
  • Piher PT15NV18 to sense the dial position (carefully positioned)
  • Microcontroller to handle I2C, Serial, DI/O, button press, dial position, light sensor
  • NVM to manage special settings, like turn off timer or LED intensity preference

I plan on doing this for myself but open to building more and documenting if there is demand or someone just wants to play.

I honestly would love to have something like this but even in winter my wife likes a cool

I have gone through several heated mattress pads that you currently have. Wife uses it so much the pad stops heating as hot after a few years. I smartened the dial controllers by soldering a wire to each side of the button and then I have a Zooz Zen16 that “pushes” the button via dry contact relay. Button still works manually too. Has worked well for over 5 years and I got huge WAF by doing this.

The ones they make for queen/king sized beds have dual controllers.

You can both be comfortable! This is the one I have:


I like that straightforward approach. It would literally resolve 90% of what I want to do with 1% of the effort. Mine is certainly not an exercise in rationality.

Some things that I still want to tinker with:

  • On/off status tracking so I can coordinate off-time with my alarm
  • Initial few minutes of On time at a higher preheat level
  • Increment the heat level if the room temperature drops
  • Monitor voltage/current each PWM cycle for issues with power or load
  • Red/Yellow/Green LEDs (instead of just Red) for visual indicators

I do have a zigbee power meter plug connected to the mattress heater as well so when voltage is greater than 0 I know that it is on. I have a custom app I wrote that tracks the power and if greater than 1 turns on a virtual switch. I can also turn on this virtual switch via dashboard, HomeKit, etc and it will actuate the relay to turn on the heater as well. Then I have a setting within the app to turn of the heater after X minutes - 30 minutes for me and 60 for my wife.

This will be much more complicated and something I don't deal with. Wife keeps hers set to Hi always and mine is set to 9. Being able to automatically turn off the heater in a set number of minutes satisfies our need to not have to adjust the temp.

When I was working on the road I would get to the Hotel in Iowa in January and turn the AC on.. yeah, they really liked me..

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Freezing GIF

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I use this one...

All controls are available through their app and can connect to Alexa/Google. If you connect it to Alexa and use Echo Speaks, you can send it voice commands with Hubitat. :eyes: