I did a flight outdoors this morning; as expected the flight was rubbish but I got the diagnostics I wanted: the IMU dropped by 0.1 degrees during the short flight – a negligible amount which rules out IMU temperature drift as the cause for Phoebe’s motion drift.
After a bit more LiPo digging I found out:
- they work best in a range of 20 – 60°C
- a modern LiPo has such a low internal resistance that it doesn’t heat up even under heavy load
- as a result, the battery needs to be charged at >20°C, and warmed up to the working temperature band prior to cold flights.
- microwaved dry rice seems to be a common way to give the batteries a pre-flight warm up.
So I need to put together a system to warm up the battery prior to flight, and insulation to maintain the heat during the flight.
The cunning plan is hatching. More anon.