Powering of 8266 (ESP-01) based sensor from battery

I want to add add an ambient light sensor to my home automation project (to switch ON and OFF the wall light). The best way if I put esp8266 based sensor in to the corner of one window, but I don’t want to use wires for powering of device.
Is there a way to keep esp8266 in a sleep mode and wake it up, e.g. once in 1 - 2 minutes, measure the light level and put it back to sleep?

There are many, and mostly non Blynk specific… have you Googled this issue?

I would also recommend searching this forum for the keywords deep sleep.


I have found some deep sleep solutions. Am I correct that it is not possible to have Auto Wake-up feature with ESP-01 (where only GPIO0 and GPIO2 are available)?

@vitalis deepSleep is possible with ESP-01’s. From way back in Jan 2015 https://tim.jagenberg.info/2015/01/18/low-power-esp8266/

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Soldering gpio16 on esp01 was about the worst thing I have been through. Not recommended :dizzy_face:

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Thanks to All!

I think I was able to modify ESP-01 for deep-sleep according to that description. So, ESP device goes to sleep every 120 sec - I can see the drop of consumed current from the USB watt-meter.

I was not able to power ESP from cr2032 - the power voltage barely reached 2.8v, Am I correct that it is not enough for ESP8266? What is a typical battery power source for your deep-sleep devices?

Looking forward to receiving the ones I ordered.

Bit low, aim for 3V min.

The 18650 3.7V batteries (4.2V fully charged for a short duration) with an AMS1117.

Good I will go for the same solution.
Does AMS1117 work well with ultra low power solutions? Datasheet said that the V drop-out voltage is 1V, is 3.7v enough for V-input?

There is no perfect solution for deepSleep systems.

I see. Perhaps I will go with AMS1117 powered from 3 AA batteries. It will bring more room for drop-oup voltage

That’s actually quite a good system as long as you have space and the additional weight is not a problem.

Depending on the max current draw you expect in your project, you could go even lower… for example, searching through Mouser I found a LD39150DT33-R that will supply 3.3v from up to 6v input and MAX 80 mV dropout at 300 mA.


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Going to visit local electronic shop for LDOs.

By the way, does .getVcc() function work with ESP-01? Can I use it for battery level monitoring?

Try it and let us know… but as for battery monitoring, no, not really, as it is only internal reading. It might work as a last minute warning between 3.3 and whatever voltage the chip shuts down at, but you would have to experiment i think to test that.

Yep, I will try to measure it. Ideally it will be good to connect ADC before linear regulator. Maybe I can hack ESP-01 a little bit more.

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One of the “USB testers” that I ordered arrived today so I’m going to scribble some notes here regarding “fake” 18650 9800mAh batteries.

Calcs might not be right but what the heck.

2 off 3.7V batteries fully charged in series giving 7.98V. Wired up as the input to the tester (allowed input 3.6V to 30.0V). Below 3.6V the screen becomes too faint to read the data.

So ideally the batteries should provide something like 72.5 WH (2 * 3.7V * 9.8Ah).

Connected a Leonardo to the output and wired up a WeMos to 3.3V and GND on the Leonardo.

Before connection the current draw is 0.03A (presumably the LCD display on the tester), adding the Leonardo takes that up to 0.07A and adding the WeMos to 0.14A. Therefore WeMos is drawing 70mA which is about right.

At present the batteries have provided almost 2.0 WH’s with very close to 1W ongoing energy usage.
So the batteries in theory should last another 70 hours.

From earlier usage of the “9.8Ah” batteries I assessed them to be about 1Ah so the pair might give 7.4 WH and expire in the next 5 hours.

Will provide further details as time goes by.

I also have some 4200mAh 18650’s and I think from memory they were also approx 1Ah. Only have 1 tester at the moment so I’ll have to wait for the first test to finish before checking these.

Not recommend for battery powered projects. High quiescent current, ~5 mA

Get the RT9013, Same as on wemos d1 mini.
Though it takes max 5.5V its quiescent current is at 25uA at 5V power supply

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Thanks! Ordered it

Update: Tester now showing less than 4.2V for the 2 off 18650’s after providing just 5.3WH of energy. Think the Leonardo will power off in the next hour.

USB tester is struggling now down at 3.5V and 5.5WH recorded.