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Battery powered, wireless temperature and humidity sensors

in my last post, I wrote about how I made battery powered temperature and humidity sensors for my home automation system. In this post, I’ll describe how I improved them.

I made two main improvements to the sensors, firstly I removed the LEDs from the esp8266, in order to increase the battery life, then I put all the sensors in small plastic boxes, which protects the circuits while making them look way nicer.

Improve power consumption

Using the deep sleep ability of the esp8266 chip, i managed to reduce the power ocnsulption greatly, which a;lowed me to last about a week on batteries. However, the leds mounted on the esp8266 were still drawing power all the time.

The solution is really easy, I just unsoldered them using my solder iron and a pair of pliers.

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The LEDs lying on the side.

Well, that was easy. Next step is to put the modules in boxes.

Putting the modules in boxes

The DHT11 module (that senses temperature and humidity) will have to stand outside of the box, so the measured values are as close as reality as possible. Check out the picture legends for a description of each step!

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First, remove the sensor from it’s breakout board, the board contains a resistor and a cap (just basically creating the recommended circuit for the DHT11).
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Place is critical, and the part on the right was not used, so I removed it using my Dremel and a cutting disk
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Looking good, the sensor goes on the right and the microcontroller (the esp8266) on the left (from top to bottom: ground, data, vcc)
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Solder some headers on the board
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4 board ready to go on the plastic boxes

 

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painting the shells as the blue is very ugly
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result is okay-ish
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could be way better
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still better than the blue

 

 

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preparing the plastic boxes for drilling (you can see the black dots)
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the sensor board inside the box

 

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view from the outside, only 4pins sticking out

 

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solder the sensors in place
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Looking OK, if only the color on the sensors was better made…

 

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Connect everything
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the cables going to the sensor
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Connected to the esp8266
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stuff everything inside
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Close it, it’s ready! note the Domoticz device ID for easy identification
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My workshop is fairly big, but for some reason I ALWAYS end up working on a 15cm² area, with a huge pile of mess all around
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Looking great!

Working on these gave me lots of ideas for different sensors, stay tuned!

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8 Comments

  1. Can you tell me how many time your temperature sensor works with two batteries??

    • Benoit Dumas Benoit Dumas

      Hi there,

      The battery holds for a bit more than a week, it could hold longer but the power board uses some mA all the time, draining the battery uselessly…

  2. Colin Colin

    Out of curiosity where did you get the small enclosures. Great projects btw really enjoying the posts.

  3. Simeonof Simeonof

    Hi man, you can use an ht7333 low power voltage regulator to power the board,and also you can power temp sensor via gpio0 pin,so when esp8266 deep sleeps it wont`t drain any power. Just make sure to set gpio0 pin high wen it weaks. Better use dht22 – it is more accurate and works fine down to 3V. My setup is similar,but I m expecting about 6 months battery life with 15 minutes sleep time. Also there is another usefull option to send battery percent and RSSI to domoticz. 😎

    • Benoit Dumas Benoit Dumas

      Hi there,

      Thanks for the tip! I ordered a couple of the HT7333 for my next project, let’s see how it goes.
      Do you have some kind of protection circuit for your batteries?

      Cheers,
      Benoit

    • Adrian Adrian

      Hi,

      Can I get more info about your setup? I would like to build a wireless temp sensor for domoticz, which runs on batteries.

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