So probably it has all been discussed but the big ESP32 & SX127X topic doesn’t give makers a clear advise on what are really the best boards to use atm.
So I hope this thread will still be useful.
Those sound more like “failure to enter sleep” current readings.
The ESP32 has fairly limited and awkward suspend capabilities compared to a true MCU. Almost any ARM Cortex part will be more flexible than an ESP32 or ESP8266 in this regard.
However, just having the right chip isn’t enough - there are 1000 ways to get low power hardware and software design wrong, any of which will cause a failure to achieve your goal. Many boards have been fabbed with just one little mistake which costs a few hundred out-of-spec microamps, and cannot be fixed without a respin. Meanwhile various software bugs can cause things to stay awake when they should sleep.
Thinks to watch out for:
Oscillators left running, especially TCXO’s
Signals asserted against pulling resistors
Signals driven to powered off peripherals, which end up trying to run off the I/O in place of the missing supply
Debug interface connections donating or stealing power
Getting stuck in a non-sleep software state
Peripheral chips not configured to low power state
Currently I’m using an Adafruit Feather M0 with RFM95 LoRa radio and needed to get it into deep sleep to preserve battery life. Unfortunately the best I could do with the stock Adafruit Feather board was to get a sleep current of about 80uA. My approach to resolve the issue was to develop a extremely low power Feather Wing board to control power to the device I was able to reduce sleep current to 16uA and in some configurations 220nA. Greatly expanding my battery life.
The Feather Wing I designed, includes a very low power RTC and a 6 axis accelerometer. Together these devices can switch power to the Feather M0 board on a time or 6D/4D orientation change or motion detection event.
Perhaps a similar approach is possible for your design.
True. @ecosoph do you have any other requirements other than low power consumption? If you are looking for a solar recharging dev kit, I would caution against using LiPo for unattended, outdoor applications. At a minimum, you’ll want to monitor battery temperature to ensure you are not charging outside of spec.