ESP32-wroom sensor BOX

[johnynov]

Hi,
I'm currently building a cube which will contain Esp32-wroom, humidity sensor, temperature sensor and pressure sensor.
The key thing is to have it waking up each 15 min make a measure and push to ThingSpeak page with MQTT -- and work up 2 two YEARS on single battery 3V.

My question is: In your opinion - which sensors on normal studens budget will fit my project?

Cheers!
Jan

[kolban]

When an electronic component operates, it consumes current. You will usually find those described in the specifications of the device. For example, if a component is documented is consuming 100mA then that is the current it is consuming. When you look at a battery, you will find it rated in amp/hours ...for example 1200mAh. That says it can source 1200mA continuously for one hour. If your device were consuming 100mA, then it could continuously run for 12 hours.

So far so good.

Now consider that the device doesn't need to be consuming power all the time. Imagine it were on for 4 minutes every hour (or 1 minute every 15 minutes). That would then say it is on for 4/60 or 1/15 of the time. This would then give you a 15x factor improvement thus giving you 12x15 = 180 hours of operation.

Now 2 years is 2*365*24 hours or 17520 hours. Lets assume that your device needs to operate for 15 seconds every 15 minutes ... that gives us 1 minute per hour of current consumption or 1/60th of an hour. That then gives us 17520 / 60 = 292 hours of current consumption over 2 years. For a 1200mA battery, that then says you need to do better than a device consumption of 4.1mA.

Now ... my thinking may be all washed up here ... but I don't believe you are going to get anywhere near that AND include radio communications using an ESP32.