Out of curiosity, when flying in low temps what change in battery temp do people see while flying? For example, if the air temp was 10F and the battery temp at startup was, say, 20F, what change would you expect to see while flying? Given the high power loading on the battery and the internal resistance the simple act of operating the copter will tend to heat up the battery and that would tend to counter the tendency to lose temp due to colder air temps.
The reason I ask is if you were planning to preheat the battery before flight would you want to heat it to 86F (30C) with the expectation that the temp will go down a bit or would preheating to 86F cause the battery to overheat in flight?
Difficult question given the difference in air temp, but I'm curious to know about what temp to reheat the battery to maximize performance and minimize problems.