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The Internet of Things is eating everything alive, and the world wants to know: how do you make a small, battery-powered, WiFi-enabled microcontroller device? This is a surprisingly difficult problem. WiFi is not optimized for low-power operations. It’s power-hungry, and there’s a lot of overhead. That said, there are microcontrollers out there with WiFi capability, but how do they hold up to running off of a battery for days, or weeks? That’s what [TvE] is exploring in a fantastic multi-part series of posts delving into low-power WiFi microcontrollers.
The idea for these experiments is set up in the first post in the series. Basically, the goal is to measure how long the ESP8266 and ESP32 will run on a battery, using various sleep modes. Both the ESP8266 and ESP32 have deep-sleep modes, a ‘sleep’ mode where the state is preserved, a ‘CPU only’ mode that turns the RF off, and various measures for sending and receiving a packet.
The takeaway from these experiments is that a battery-powered ESP8266 can’t be used for more than a week without a seriously beefy battery or a solar panel.
Power consumption and battery life remain limitations for IoT applications. How can they be overcome?
(Score: 2, Interesting) by Anonymous Coward on Monday December 17 2018, @10:34PM (1 child)
Wake up every fifteen minutes to take a reading and send it over MQTT, then back to sleep. I've got a project that's been running like that for months on an 18650.
(Score: 4, Interesting) by VLM on Tuesday December 18 2018, @12:24AM
My experience with a ESP8266 is you actually need to set up a for loop to do that about 96 times and then software reset the device to handle memory leaks or WTF is wrong with it, but yeah, to a first approximation you're correct.
Also extra bonus hilarity for waking that sucker up then waiting for DHCP and all that junk. So its not like its awake one ms out of every 15 minutes its more like its awake a good ten seconds every 15 minutes. Still super huge power savings of course.
The MQTT server is a microscopic slice of a rack of vmware ESX cluster servers that draws about a kilowatt so your energy budget is kinda vague and hard to define. I'm probably averaging well under a watt for my rabbitmq instance which is a lot less than a pi, although the capital costs of the cluster are slightly higher than yet another raspi.