High compass interferance during AUTO mission

ArduCopter Copter 4.0
1

Hi

Im using E616 Agri frame ( X8 -hexacopter) Hobbywing 100KV motor, battery : 12V 60000mAh battery.
Here3 GPS: Using only external compass.
During auto mission i got high compass variance, then tried motor - compass inference and found the inference is 55 so i increased GPS height from 7cm to 12cm then after that i tried Motor - compass calibration and that time interference was 35 so i tried taking off but during takeoff and land again compass crossing > 0.5 .
Attaching Auto mission log file and calibration screenshot for reference , kindly provide me suggestions to solve this.

Screenshot (27)
Screenshot (27)1920×1080 286 KB

Screenshot (37)
Screenshot (37)1920×1080 208 KB

Link for bin log:

2

It is better to use the on line magfit tool after doing the calibration you did.

There is a YouTube video explaining how to use it

3

Thank You ! I will try and keep you updated.

4

Can I know why it is occurring / what is causing ?

5

compass interference is caused by magnetic fields produced by electrical current.