AA batteries – Squix – TechBlog https://blog.squix.org Tue, 13 Dec 2016 20:28:53 +0000 en-US hourly 1 https://wordpress.org/?v=6.5.8 121913304 ESP8266: R.I.P. Long Term Data Logger after almost 3 months. https://blog.squix.org/2015/07/esp8266-long-term-data-logger-rip-after.html https://blog.squix.org/2015/07/esp8266-long-term-data-logger-rip-after.html#comments Sun, 26 Jul 2015 10:07:00 +0000 http://blog.squix.org/2015/07/26/esp8266-long-term-data-logger-rip-after/ Read More

]]> Yesterday evening the ESP8266 the data logger connected for the last time to Thingspeak and posted temperature and humidity. It has reported these values every 10 minutes for 2045 hours or in other words 85 days. This is nearly 3 months!

ESP8266 posting temperature and humidity every 10 minutes
for almost 3 months on 3 AA batteries

In the last few days the DHT11 had started reporting bogus data, probably the voltage was insufficient to do a correct reading. While the reported temperature continued to look reasonable until the end you can’t say the same about humidity. It kept toggling between 95%, 43 and 0%.

Summary

All in all I’m very impressed that the setup could last so long. It was so stable that it would run on its own, without ever restarting it. In the same duration I had misconfigured my access point and had to set it up again and my internet provider had produced a 10 hour “internet blackout”. Now the three cells have each a voltage of about 0.9V.
Maybe with a few additional tricks and without the AP/ internet blackouts the batteries would have lasted longer (fix IP, feeding DHT11 voltage through GPIO pin, etc). But it’s already an impressing duration for a simple setup.
Have a look at the history of this experiment:
Shopping List:

]]> https://blog.squix.org/2015/07/esp8266-long-term-data-logger-rip-after.html/feed 9 34 ESP8266: Wifi data logger already running for more than 2 months on batteries! https://blog.squix.org/2015/06/esp8266-wifi-data-logger-already.html https://blog.squix.org/2015/06/esp8266-wifi-data-logger-already.html#comments Tue, 30 Jun 2015 17:22:00 +0000 http://blog.squix.org/2015/06/30/esp8266-wifi-data-logger-already/ Read More

]]> More than 1440 hours or in other words 60 days ago I put 3 AA batteries from IKEA in the battery box of the ESP8266 test board and started a program that would send temperature and humidity every 10 minutes to Thingspeak through its Wifi interface.
I removed all unnecessary power consumers from the board such as LEDs and light resistor but there would have been more potential to improve longevity of the batteries. By setting a fixed IP to the module I could have saved a little bit of online time.

Austerity Engineering

While I could measure the energy consumption during the deep sleep phase quite well it was rather hard to guess the consumption during the awake phase. My pessimistic estimation was that the batteries would last 30 days. And now the setup just passed the magic 1440 hours mark!
That means that with a little bit austerity engineering (sorry, not politically motivated) one could have this running for a long time. Depending on your application you could wake up the device only into a non-wifi mode, check the periphery and go back to sleep if nothing requires you to connect to the internet. Since Wifi is the real burner here that should save you a lot of your battery reserves.
I take bets for how much longer the setup will run.

Current voltage of the batteries

30 days ago when I posted the last update I was asked to measure the voltage of the batteries. I chickened out until now because I was afraid to influence the experiment. But curiosity won over fear once again and I measured the voltage of one cell: 1.323V after 60 days, compared to 1.623V of a battery of the same batch. This means that there are only about 4V fed into the voltage regulator and the difference to the 3.3V of the ESP8266 is only 0.7V….

Voltage of one of the three AA cells after 60 days.
An unused battery of the same batch has 1.623V



Code

]]> https://blog.squix.org/2015/06/esp8266-wifi-data-logger-already.html/feed 5 38 ESP8266: Long Term Data Logger Test with Batteries https://blog.squix.org/2015/05/esp8266-long-term-data-logger-test-with.html https://blog.squix.org/2015/05/esp8266-long-term-data-logger-test-with.html#comments Fri, 01 May 2015 17:12:00 +0000 http://blog.squix.org/2015/05/01/esp8266-long-term-data-logger-test-wi/ Read More

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Today I started a (hopefully) long term battery test with the ESP8266 board I reviewed here. The conditions are:

  • powered by 3 AA batteries (serial)
  • every 10 minutes update temperature and humidity retrieved from a DHT11 to thingspeak
  • go the deep sleep between the posts
The test board comes with a light resistor and several LEDs of which one is a RGB led. For some reason I couldn’t turn them off completely so I just chopped them off. Before the surgical change the board consumed 1.3mA in deep sleep mode. After only 130µA. This is still almost factor two away of the 67µA I read somewhere in the web, but not bad for starters. With this the board could theoretically survive more than two years in permanent deep sleep. This experiment will show how much the wake-ups costs and if theory es even close to reality. 



Code

The Test Setup: all LEDs removed
from the board to save energy
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