The voltage levels logged during these tests were from 4.67 to 4.776V. The mayfly was powered via USB and LiPo.
I don’t know the Digi firmware version number on the XBee, but it was installed July 25, 2019. Additional background: What we’re attempting to do is to take this station and update it so that it’s more lenient on battery voltage threshold for data transmission, and so that it will flexibly choose the best cell carrier based on signal strength. To do this update, we’ve programmed a new Mayfly with the latest ModularSensors (don’t know whether the existing Mayfly is using that lib or not), and have moved the XBee, LTEBee, SIM, LiPo, and SD card from the existing to the new Mayfly. The existing Mayfly has been successfully communicating (when its battery and cell signal strength are sufficient).
You mentioned us hitting issues with the UBee, but we haven’t been using one here.
It sounds like our next step should be to apply your latest TinyGSM fixes and re-test, switching between Bypass and Transparent to try to beat the XBee into submission.
Question: How many sleep/wake cycles would you suggest I let the Mayfly run before I abort, make a code change (e.g. the Bypass/Transparent switch), and re-test? While debugging, I’ve set the logging interval to 3 minutes.