Just wanted to provide some helpful information…I searched everywhere on how to disable the inactivity timer in the ardupilot firmware and I couldn’t find anything. As a developer with the drone connected for hours, it is a real pain to constantly have to shut off the alarm.
The alarm comes from the ESCs if they are powered for more than 10min with no throttle input. To disable, you have to connect to each ESC and turn off the inactivity timer.
I tried the passthrough method via the pixhawk4 and blheli S ESCs from holybro, but it didn’t work. I did find a helpful video on how to disable. You just need an arduino nano. See here: Arduino Nano - BlHeli firmware programmer - YouTube