Idea and suggestion for a battery powered system

I’m trying to do some battery powered sensors for general domotic purpose.

Question for hw experts:
what’s the best solution in your opinion to run a battery powered domotic system? ESP8266 or Arduino micro modded + NRF24? please give also some comments to your choise


i use ESP8266 with 2 x 18650 battery and eBay PSU

but i only need 6 x I/Os so depends on how many GPIO’s you need… how many does the Micro have?

@joepesce I have some NRF24’s but I have never used them but I believe they are low power.

What I can say is that running ESP’s on batteries is quite difficult. The “9900mAh” 18650’s that are for sale at a $1 a piece will last around 8 hours on continuous use, but bear in mind the English translation of “9900mAh” is “1200mAh hence the low price”.

So a genuine 18650 of say 5400 mAh that might cost $20 to $30 would last a day and half before it needs recharging. Not long but can obviously be extended by using deepSleep but then a lot of the benefits of an ioT connected device are lost.

I have around 30 of the $1 18650’s and they are actually good value but I wish the suppliers would use the correct English translation (“1200mAh hence the low price”) in their marketing materials.


lasts 3ish weeks on 720 seconds sleep cycle…

What mAh and cost are the batteries @Dave1829?

I think that use of deep sleep is mandatory for this kind of project

I guess so but then it is not very Blynk friendly.

it’s not “difficult” at all…

maybe it requires “good coding” but it is not “difficult” per se

i paid $5 USD ea for them, they are marked 4000mAh.

Are you trying to say I am a bad coder @Dave1829? :grinning:

IMHO batteries and Blynk are not a good marriage however good your coding skills are.

How many seconds is the ESP on for between the 720s sleep cycles?
Just want to do a quick power check.

i am only as good as my teacher :wink:

my use is sensor node, not my main house controller.

sensor node only needs to talk to blynk every 10 mins or so to be helpful.

trying to run my ventilation controller off battery would be INSANE!

can you write the code for that quickly?

startMillis = millis()

totalMillis = millis() - startMillis

is that it?

(it is on OTA update, so i dont have to go outside to reprogram, but i do have to wait til it wakes from deepSleep again!)

Looks about right.

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Do you have a widget (slider) that you use to stop it sleeping when it wakes?

yes, but just got:

Update Failed!

trying again…

Bad coder Dave.

@joepesce are you able to say more about your project as it may help if people knew what the batteries have to do?

i’m getting between 4 and 4.6 seconds…

these are the batteries:

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Thanks for the details Dave. I’ll get my calculator out.

1.75 hours per battery then if they run for 21 days.

The words mistreatd and shildren on the batteries suggests the manufacturer is not an native English speaker.

The 1.75 hours suggests they weren’t top of the class in Physics or Law at college.

As I said a battery that has the power stated on the label, above 1000mAh, costs $20 to $30.

Looks like you have a “BME” @Dave1829. Did you specifically set it up to use almost zero power when the ESP is sleeping?