Yes, I’m pretty sure there is a temperature sensor in the battery that prevents over-heating during flight.
The fan starts immediately even during cold temperature and there may be a correlation between fan speed and the battery temperature but I did not remark that.
I was just thinking :
- The battery, In usual Exterior Temperature as above 10°C, is always ‘too hot’. The main risk for the battery in normal operating is the over-heating.
- During flight, the motors do generate heat due to friction, the ESCs draw current and do heat (touch them on a racer, whatever the Exterior temp... they’ll burn your fingers, I have even burnt ESC on a little tiny whoop).
- The GPS sensor and the main board, as well as the barometric sensor, the magnetometer, and gyro or accelerometers may not be that much influenced by low temperatures. In the contrary, a low temperature is what is searched for main boards, and thermal expansion has a bad influence on MEMs sensors such as the accelerometer.
To me the risk of the low temperatures is mainly on the battery at startup (stayed long in a non-heated environment, the garage or car during winter...). To reduce this risk, the advice is to keep the battery in your coat before flight in winter’ and store the battery inside the house at night (which Lambo did)
The second risk for the battery is the low temperature affects the chemical process in the lithium / carbon exchanges of ions and reduce dramatically the efficiency of the battery at low Exterior temperature particularly when ‘almost empty’ (at that low Exterior temperature when the voltage goes low, I would not start the Anafi fan during RTH to avoid cooling more and draw unnecessary current from the fan that is useless in this situation).
The last risk is propeller ice depot and stall but is was not the case here (though propeller icing was reported by the guy who did a beautiful winter snow footage over Switzerland but it did not induce the Anafi stall).
The altitude has of course an effect on the temperature (you loose 2°C every 1000 ft/ 330m in the ‘standard atmosphere’). But at 50m the decrease in temp should be less than a degree and should not be an issue in the case. The wind speed at 50 m heigth can be doubled and participates in the cooling process I suppose.
That’s why I was wondering if there was an other temp sensor ‘far from the battery or the parts that heat during flights’