ESP32 powered for atleast a year

Question

How to power esp32 board this one with soil humidity sensor that sends data to server via wifi every 30 minutes for something around a year on battery? What battery type and capacity should I use for that? Or is there any better board you would recommend for this pourpouse? The setup will be indoors.

• Dave Newton: There's no generic answer, it depends on the actual circuit and its power consumption. If outdoors (and some indoor setups) I'd say solar + battery.
• hcheung: Your question is too broad without experimental, for example, have you done the measurement of your board when it is in operation, and when it is in sleep mode? Only when you have those values, you can then decided on whether it is a suitable board or not (e.g. does it cut off the USB chip when in sleep mode)? Choosing the battery depend on your form factor and application, as well as your circuit design. You can only decide that once you done the measurement an calculation.

Answer 1

Okay, let's do some calculations.

Assume that device sends data for 5 seconds (turn on, connect to the Wi-Fi, and so on) and drains (according to the docs) about 0.2A.

So, it works for 5 (secs) * 48 (turn-on's) / 60 minutes per day for 365 days.

So, it works for 5 * 48 / 3600 hours per day for 365 days.

So, it works about 24 hours per year.

0.2A for 24 hours is 4.8A for 1 hour.

Assume that efficiency of the power regulator is 80%

4.8 - 80 % X - 100%

X = 6 A*h

So, take three (to compensate self discharge and have some headroom) standard Li-Ion cells, or mid-size (about 8000 mAh) power bank, and you well be fine.

But you shall add some external clock (powered by own CR2032 cell), that will be turn power regulator and esp-device ON every 30 minutes.

• dandavis: I would use ESP-NOW instead of wifi. It can boot, read, and publish in well under 500ms instead of 5 seconds. On the 32, you could also probably craft a ULP routine that would only bother to fully wakeup+report if the moisture level changes.