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Comment by jsheard | Hacker News Reader

Aren't ESP32s way more power hungry than typical BT-only parts though?

Not insanely for a smart watch. Your smart watch battery will be something like 200mAh, so for 20 hours you need to average 10mAh. With zero optimisation, screen refresh rate at 30+fps, I have smart watch chewing 30mAh.

Getting down to 10mAh is not so bad. If you're not actively driving the display, you can under-clock significantly [1], if you're not using WiFi you can turn the modem off [2].

[1] https://docs.espressif.com/projects/esp-idf/en/stable/esp32/...

[2] https://docs.espressif.com/projects/esp-idf/en/stable/esp32/...

It might be just-about acceptable for a smartwatch. But anything the micro takes out of the power budget means less screen and radio time, which does add constraints.

PineTime, based on NRF52, will get you 4-7 days of practical usage.

There are ESP32 watches. One I have[1] comes with quite thick 940mAh battery but my understanding is the battery life still isn't that amazing (just got it, haven't really tested the battery) - something like less than a day of constant runtime or few days if you turn it off constantly

[1] https://lilygo.cc/products/t-watch-s3-plus

Yeah I got one of those as well. An the older non-S3 version. Fun for developing, very powerful. I use it for developing ML applications for watches etc (emlearn project). Great device for that, but battery life is not its strong point.

I have a similar one with a microphone, I dread to think how the GPS module and LoRa of that variant affects battery life!

Can confirm, I regularly get about 9 days of charge on my PineTime, running the latest PineTimeOS release. Its gotten better and better over the years, and the functionality keeps coming ..

I used to use the PineTime with PineTimeOS, but mine eventually broke (corroded inside), but not having WiFi made it annoying to develop for. With WiFi suddenly you don't need to communicate regularly with a phone and the possibilities really open up.

I get that kind of experience with the Watchy… but the problem is, its quite a bulky device and gets a bit tiring to wear after a while.

no, esp32(the original one) is insanely power hungry, especially its radio.

Also 20 hours of runtime is horrible.

I'm getting 10 hours run time with the screen continuously running and drawing graphics every refresh in micropython - extending this time out is definitely possible.

There are many ESP32 variants, depending on what you pick some may be more compelling for your use-case.

Well, we are talking about smartwatch use case.

Even some newer variant like S3 or C6 only has acceptable power consumption, if what you are after is run-time they are not the best fit.

Does this apply to C-3 and C-5 as well?

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