Quadcopter sudden fall and crash while doing Autotune

Every time when I was doing Autotune for a few minutes the drone suddenly fell and crush onto the ground. I attached the four logs below and only the first log captured the status when crushing, the rest of the logs stopped suddenly and didn’t capture the movement of crushing.

I have a few assumptions for the causes of crushing:

  1. The 18650 battery. Since it’s the first time using 18650 VTC6 battery, I’m not sure whether my drone’s voltage or current exceed the limit. However according to its data sheet, the battery voltage when crushing (3.3v) is greater than its minimum voltage (2.8v), and the actual current (9.5A) is less than the limit (30A).
  2. The short circuit of the camera connected to the flight controller. Since it has been short circuited once when I was soldering the power cable on to the camera. When I powered on the drone a smoke raise from the FC. Later I fixed problem by resoldering the cable and isolated the soldering point with glue. The drone can fly quite well. However,I never performed a flight longer than a few minutes.
  3. The FC, ESC, or Motor overheated. I don’t know how to set up temperature monitor. If anyone know how to do please instruct me.
  4. Motor issue

Could anyone analysis my logs please. If anyone can come up with any other reasons for crushing please leave the comments below. Thank you guys.


Frame: 4 inch quad

Battery: Sony 18650 VTC6 2S 1P

ESC: HAKRC 32 bit 40A 4in1, Blheli-32, Dshot600

FC: Kakute H7 mini

Motors: HGLRC Aeolus 1303.5 - 4500KV

Propeller: Gemfan 4019

GPS & Compass: HGLRC M80 pro

No logs. Attach a link to wherever you store them in a cloud service, you can’t directly attach them. If there is more than one log explain what they are.





Sorry I posted the logs below

Which of the logs shows that it crashed?

The first one shows the crush. The other logs didn’t capture the crush

Looks to me like that Flight Controller stops logging or resets when the battery voltage reaches ~6.5V.

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Ohhhh I see. Since I’m using 18560 battery which has the minimum voltage (2.6v) lower than Lipo voltage (3.3v), and my FC Kakute H7 mini has a minimum voltage of 2S, perhaps the problem is the minimum working voltage of my FC is 6.6v (2x3.3v) which is higher than the battery. Do you think the reason could possibly be this? :slight_smile:

That seems likely. Might not be the only issue but it certainly is one.

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Not sure. I had a quad on 2S li-ion and it worked fine (Matek H743-Mini) Obviously the higher voltage BEC outputs didn’t work but the FC and ESC did.

I switched to a 3S lipo, re-configured and it’s a better flying craft.

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I’ll try to use a potential transformer to rise the voltage since there’s no space to store an extra piece of battery to make become 3S

What exact 18650 cells are you using?

The Sony VTC6 18650 Batteries

I increased the Flight Controller power voltage to 12V and changed the motor to 1-3s motors, but the problem still exists. The drone still falls to the ground went voltage falls below 6.5V. Below is the Log.


I think this might due to the problem of my ESC, but the manufacturer told me that this ESC can still working till 3.5V. Has anyone tested the HAKRC 4in1 40A ESC?
Or can anyone come up with any other reason for the crash?

Is low voltage cut/off enabled on the ESC? Check from BLHelisuite. That would have nothing to do with the FC logging stopped problem though.

Sorry, I can’t find the low voltage cut off option.

Low voltage protection is already off.

Here’s another log of crash. I reviewed the latest flight logs, none of them stopped logging in a sudden.