[G6EJD] wanted to design a low power datalogger and decided to look at the power consumption of an ESP32 versus an ESP8266. You can see the video results below.

Of course, anytime someone does a power test, you have to wonder if there were any tricks or changes that would have made a big difference. However, the relative data is interesting (even though you could posit situations where even those results would be misleading). You should watch the videos, but the bottom line was a 3000 mAh battery provided 315 days of run time for the ESP8266 and 213 days with the ESP32.

The fact that the hardware and software only differ in the central processing unit means the results should be pretty comparable. [G6EJD] accounts for the current draws throughout the circuit. The number of days were computed with math, so they don’t reflect actual use. It also depends on how many samples you take per unit time. The goal was to get operation on batteries to last a year, and that was possible if you were willing to reduce the sample rate.

While we generally like the ESP32, [G6EJD] makes the point that if battery life is important to you, you might want to stick to the ESP8266, or look for something else. Naturally, if you are trying to maximize battery life, you are going to have to do a lot of sleeping.