ESP32 on Batteries - your setup

[meneldor]

Guys, seriously, does ESP32 on battery project(using wifi of course) even exist? I did alot of search and cant find anything usable.

[woofy!]

Guys, seriously, does ESP32 on battery project(using wifi of course) even exist? I did alot of search and cant find anything usable.

I am using an ESP32 to monitor heating oil level. It takes a reading every hour and transmits that back over WIFI to my MQTT server. It actually sends a data blob consisting of oil level, outside temperature, Battery Voltage, received RSSI and Awake time. It takes a total of around 1.6 seconds to acquire and send the data before going back to deep sleep for an hour. The data is processed with node-red and the image below is from the node-red ui. I calculated the battery (3xAA cells) should last about a year. I implemented it near the end of last year so it has been running for nearly four months now. In that time the battery voltage has gone down from 4.5 to 4.2 volts. It's measured whilst the WIFI is connecting so should be during maximum stress.

[meneldor]

Unfortunately my project cannot sleep so long. Im measuring temp,humidity and air quality. Those sensors require some time to measure. Also, i need the values at least once per 2 minutes.
Somebody mentioned a back feeding the ldo. I've ordered a bare ESP32-WROOM module and gonna use better ldo.

[woofy!]

If you don't really need the data to actually be sent every 2 minutes, you could wake up every 2 minutes and just log the data before going back to deep sleep. Then once per hour send it over WIFI. That would save you a lot of power.

[meneldor]

If you don't really need the data to actually be sent every 2 minutes, you could wake up every 2 minutes and just log the data before going back to deep sleep. Then once per hour send it over WIFI. That would save you a lot of power.

I know, but im using the data asap (not less than 1m) for presence detection.

[woofy!]

Perhaps the ESP could wake up every 2 minutes and check the readings against the last lot sent.
Then it would only need to alert you to a change. Depends on how quickly the data changes though.

[rin67630]

If you don't really need the data to actually be sent every 2 minutes, you could wake up every 2 minutes and just log the data before going back to deep sleep. Then once per hour send it over WIFI. That would save you a lot of power.

I am currently planning to do that. I write a data logger that gathers data every second and light sleeps between for 900mS. Deep sleep is not efficient at that pace.
[Addendum] Sleep is a bad joke on the ESP32: the "RTC" does not desserve its name, it drifts by minutes an hour! you will else need a xtal on GPIO 33,32 and the ESP32 IDE to be able to enable it.

My problem will be to write the Data to SPIFFS and to transmit it via FTP each hour... while continuing to gather data every second.
Normally you use FreeRTOS to run two tasks concurrently, but how does it cope with power and sleep phases?

[mega128]

Hi Woofy,

I was wondering if your project is still going strong after four months? Also, did you use a LDO regulator or directly connected 3xAA cells to ESP32? Any electrolytic cap you added after LDO if you used a regulator?

Thanks

Guys, seriously, does ESP32 on battery project(using wifi of course) even exist? I did alot of search and cant find anything usable.

I am using an ESP32 to monitor heating oil level. It takes a reading every hour and transmits that back over WIFI to my MQTT server. It actually sends a data blob consisting of oil level, outside temperature, Battery Voltage, received RSSI and Awake time. It takes a total of around 1.6 seconds to acquire and send the data before going back to deep sleep for an hour. The data is processed with node-red and the image below is from the node-red ui. I calculated the battery (3xAA cells) should last about a year. I implemented it near the end of last year so it has been running for nearly four months now. In that time the battery voltage has gone down from 4.5 to 4.2 volts. It's measured whilst the WIFI is connecting so should be during maximum stress.

[tvoneicken]

FYI, I have an almost complete set of posts on using the esp32 (and esp8266) on battery. I believe it does answer a slew of questions. It's not done, 1 or 2 more posts to go... The first post on the esp32 is https://blog.voneicken.com/lp-wifi-esp32-1/ but you may want to go back in the series to read some of the general wifi power save info... Hope this helps!
Spoiler: depending on your battery size and run-time expectations it can be done but it's not easy by a long shot...

[rontec]

If your equipment is installed outdoors (or any place with direct sun light) then you can add a 1W solar panel for about $1.50 and a solar charge controller for $1.