Strange behaviour of my P3P

[Raini]

Some weeks ago I was out for a short flight on a not too windy day. The drone took off with the batteries at 52% charge but soon it complained "Critically low power" and switched to "Auto Landing". During the autolanding I tried to keep it flying by increasing throttle but then it seemed as if it was in ATTI-mode by drifting with the wind still descending until the legs touched the ground. After this the flight ended upside down. Fortunately only the spinners of all props are scatched and two have small dents but no other damage.

Can someone explain why my P3P complained about "Critically low power", where still 52% of battery power was available. Also, why did the P3P refuse to keep the GPS-position when it was in "Auto Landing"-mode?

Additionally I saw a "Motor overloaded"-message in the log that I can't explain. There was really no obstruction for any of the props whatsoever. Any idea?

Hopefully it helps that I uploaded all relevant files.

Many thanks!

 

[Meta4]

Some weeks ago I was out for a short flight on a not too windy day. The drone took off with the batteries at 52% charge but soon it complained "Critically low power" and switched to "Auto Landing". During the autolanding I tried to keep it flying by increasing throttle but then it seemed as if it was in ATTI-mode by drifting with the wind still descending until the legs touched the ground. After this the flight ended upside down. Fortunately only the spinners of all props are scatched and two have small dents but no other damage.

Can someone explain why my P3P complained about "Critically low power", where still 52% of battery power was available. Also, why did the P3P refuse to keep the GPS-position when it was in "Auto Landing"-mode?

Your second sentence has the answer.
You must have missed the section in the manual that advises that you only fly with a fully charged battery?
If your battery has been partially discharged, the % capacity indication is not accurate.
A full battery will deliver full voltage of around 17 Volts which will slowly decrease during the flight.
Look at the voltages recorded in your flight : DJI Phantom & Mavic Flight Log Viewer - PhantomHelp.com
You started at only 15.2V but when you put it under load and tried to climb, it dropped to 13.7V
Within 39 seconds it was at 13.3V which is the critical low voltage.

Don't fly with a battery that has been lying around for a few days or weeks discharging to storage level.
That's the way to have your Phantom fall from the sky.

 

[Raini]

Many thanks, Meta4! This explains a lot. Indeed, I read somewhere that it is advisable to only fly with fully charged batteries, which I normally do. The reason for my "misbehaviour" was to fly until it autolands due to low battery so that I can keep the batteries in good condition. Is there a better practice to discharge the batteries other than the buildin autodischarge-facitily that discharges only partially. Or should I fly with fully charged batteries and keep it in the air until it autolands at the 10% marker (I guess)?

 

[Meta4]

The reason for my "misbehaviour" was to fly until it autolands due to low battery so that I can keep the batteries in good condition. Is there a better practice to discharge the batteries other than the buildin autodischarge-facitily that discharges only partially. Or should I fly with fully charged batteries and keep it in the air until it autolands at the 10% marker (I guess)?

Just fly to whatever level and recharge your batteries.
There is no need to take it down to 10%, the batteries don't develop a memory and it's OK to fill them up from any level.
The auto-discharge takes it down to around 50% which is the ideal long-term storage level.

 

[Raini]

Excellent! Many thanks!