[oddlama]

Just a battery would be the simplest option. Just measure time until empty.

If you want higher time resolution, there are several fully integrated hall effect current measurement ICs out there, like for example the ACS723.

If you need even better accuracy or resolution and you can spare 100 bucks, just buy one of the Nordic Power Profiler Kits.

[ilyt]

That is the way. Once you get into actual measurement there is plenty of hard problems, like your device might only wake up for 10ms, take few hundred mAs of current and go to sleep.

[numpad0]

1.5A. Peak consumption of an ESP32 is around 1.5A. I once had to add a supercap from junk bin to Vcc to stop it from bootlooping.

[ilyt]

That doesn't sound right... it would be ~5W, WiFi is supposed to max out at 100mW (so even at 10% efficiency it would be still just a watt)