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Comment by KennyBlanken | Hacker News Reader

The ESp32 is many things - a suitable mobile battery powered uC is not one of them.

It has insane peak power draw from its radios, much more so than any other wifi uC, and it's horribly energy-inefficient when not sleeping.

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Can't beat 240MHz dual thread performance and certified wireless at $5 all-inclusive. There are plenty more proper solutions but none within the ballpark - at least until Espressif moves to investment recovery phase.

The Lilygo/TYGO ESP-32 boards I've used also have horrible battery life while deep sleeping (which is a bummer because they put out some cool boards that seem ALMOST perfect for battery use cases)

The chip itself is fine.

If you have the wrong board it will be bad. You need to pay attention to the power supply on the board.

I've got a weather display (epaper, refreshes every hour) that I need to charge every 18 months or so. If you find the right board they're pretty much perfect.

Do you have a link handy? I had trouble with an e-ink board from them that drew tens of milliamps when it was asleep (on a well optimized ESP-32 it should be more like dozens of microamps)

The firebeetle claims 10uA and from memory is pretty close on a tinycurrent, or the Unexpected Maker boards [0].

You might be able to fix your existing boards if you look at the schematic and remove any unnecessary draws (voltage measurement dividers and always on LEDs are a good place to start). To get into the <20uA range the board needs to have an LDO with a low quiescent draw though, and designed so you can shut down power to the eink driver.

0: https://esp32s3.com/index.html#boards

Thanks for the info! Do you know if it's still possible to do partial refreshes if you shut down the display in between updates? Or is best/required to do a full refresh every time you restore power?

I second that, I have an EzSBC ESP32 board [1] that wakes up twice a day to fetch data through WiFi and three standard mini 1.5V, non rechargeable batteries are still going strong after almost one year. The power supply stage is truly the most important bit when it comes to deep sleep power consumption.

[1]: https://www.ezsbc.com/product/esp32-breakout-and-development...

I've got a weather display

That seems very interesting. Got a link?

If I remember correctly there have also been a few bugs in M5Stack ESP32 APIs because of deep sleep not working, I'm thinking there's also a few underlying Esspressif API bugs.

This is one of the reasons I only use RAK WisBlock devices, which use the very low energy nRF52 chips, and are also truly industrial strength quality, and more flexible regarding many types of sensors etc. (and also have a nice small solar panel enclosure, if it fits your use case).

out of curiosity, which wifi microcontrollers are better for battery life?

ESP8266 as a daughterboard on a real microcontroller like an STM32. Or a Nordic device like the nrf7002, but I haven’t used that personally.

Nordic Semiconductor nRF devices barely sip power. We did lots of wearable devices with BLE interface at my last job and Nordic was our go-to.

Sorry, I just realized you said wi-fi, not BLE.

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