Reply To: ESP32 not reading SDI12 Implexx sap flow sensor when 35oC

Without knowing more about what board you’re using for the logger, or the software that runs on it, it’s hard to guess what the problem is with your system.  But I know that when we first used Arduino Uno boards for loggers about 10 years ago, we found that they became unreliable and inaccurate at high temperatures, both in terms of timing and analog voltage measurements.  And if your logger or various components are specified to run at 5 volts, but you’re powering things with a 12v battery, then whatever voltage regulators are on the boards are having dissipate a lot of heat in order to drop the supply to 7 volts.  That heat, along with hot ambient temperature, could be causing issues too.