u/Fair_Caterpillar7045

I have HGLRC M100 PRO GPS module (with compass) physically setup on drone as shown in image right bottom corner (3D printed a little holder so it's a bit farther away from battery and other electronics. Cable wrapped in Cu foil and grounded also with insulating tape around it).

This is the orientation I found also in the supplier docs. Docs also says to adjust Betaflight orientation to CW 180 flip. Since I'm using Ardupilot and not Betaflight, what is the correct setting for GPS orientation in Mission Planner?

I calibrated the compass (outdoors using radio switch to start calibration so I'm far from PC or any other electronics) and it autodetects rotation as Yaw270. That can't be right...

In Mission planner I can also see the drone heading is off (not pointing in right direction on map) and I'm getting pre-arm error: check mag field (xy diff: 218>125). I guess I need to manually set the compass orientation...but what is the correct setting?

Log files show GPS works fine when I fly around (some pre-arm checks disabled to get airborne) and maps the correct flight path.

I have a metal ammo box (seal removed from sides to vent) with a Modster Batsafe inside. Batsafe contains two Li-Ion batteries (6S 4000mAh, 4S 3000mAh).

I realize Li-Ion is safer than LiPO but my logic for this setup is that these batteries are strapped to FVP drones hurtling across the skies at 80km/h at 100m altitude (or more) and in case of crash and damage I need a safe place to store and move them. Also I don't have the option to store the ammo box away from flammable surfaces so I figure the Batsafe will contain a possible fire enough so that the metal box does not heat up and ignite everything it is in contact with.

Charging inside the box.

I could have bought two smaller Batsafe boxes, one for each battery, but I figure the risks are already pretty low with this setup. Thoughts?