Powering ESP32 from 18650 Battery

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sfrasernz

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#315532 23-Jul-2024 17:30

I've built a little dual probe temp monitor for my swimming pool using ESP32. I've been researching how to power it from a battery like an 18650 and from what I gather I need a buck-converter to reduce the 3.7v to 3.3v and provide stable power.

I've found this which looks ideal but I'm having trouble sourcing locally: https://www.pololu.com/product/2842

Can anyone recommend something local or from Element14 who I've used in the past.

richms

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#3263660 23-Jul-2024 17:36

I just use the ESP modules with an 18650 holder on the back of them off aliexpress which have the protection and charger all ready to go. No point using a buck for such a small drop of voltage for low current things, a LDO regulator is all you need.

There are other boards with a JST on them that are also ready to go. Generally use with a lipo pouch but close enough to the same to be fine with a 18650

Richard rich.ms

elpenguino

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#3263669 23-Jul-2024 18:38

What temperature sensor are you using?

If you're using Dallas one wire 18B20 types from aliex be aware they're counterfeit and inaccurate.

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olivernz

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#3263691 23-Jul-2024 19:37

The ESP32 is a hungry beast so that 18650 won't last long. Better off with something less grunty. ESP8285 or even better go Zigbee or something. 433Mhz works too. You'd just need something to be at the other end.

sfrasernz

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#3263694 23-Jul-2024 19:53

The DS18B20 were from Element14 so they should be good.

I wasn’t sure on the power consumption but it is in deep sleep for 60 minutes before waking for 3 minutes to send data. If the battery doesn’t last then I’ll look at other options

@richms- do you have a link to the battery holder with LDO?

elpenguino

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#3263803 23-Jul-2024 22:41

Hm, might not be too bad in deep sleep.

-- from https://www.programmingelectronics.com/esp32-deep-sleep-mode/#:~:text=The%20ESP32%20power%20consumption%20in,Low%2DPower%20coprocessor%20is%20active.&text=The%20chip%20radio%20is%20powered,receive%2C%20transmit%2C%20or%20listen.

The ESP32 power consumption in deep sleep mode varies, ranging from 0.15 mA to 150 µA when the Ultra-Low-Power coprocessor is active. The chip radio is powered up. The chip can receive, transmit, or listen.

Let's overlook the fact that 0.15mA is 150uA and assume that source is worth reading 😃

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olivernz

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#3263860 24-Jul-2024 09:07

Yeah I had stuff in deep sleep setup just as described. Long term just wasn't too happy with it and did switch to other technologies.

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richms

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#3263910 24-Jul-2024 10:17

sfrasernz: do you have a link to the battery holder with LDO?

They were the TTGO ones, I got them before the proliferation of other ESP32s back when there was only one type. Not very energy efficient in any case. never tried using them for a long time on battery or any of the sleep modes to know how well it worked.

Richard rich.ms