Ok to mount Pixhawk below battery, or does that cause electrical interference?

I’m considering rearranging things in my large Volantex Ranger EX, which has plenty of room in the fuselage. default location to mount the flight controller is very close to the motor, which leads to poor internal compass performance. rather than disable the internal compass, I’m interested in moving the controller to the nose, but that means it would be right below the battery.

how much interference will the battery cause if it’s pressed up against the flight controller?

The battery will cause interference also. You don’t have an external compass?

Good day, better you keep your fc far from the battery… you can use a fc stand support so not only you will reduce interferences but also you will reduce vibrations.
Keep also far from the fc radio receiver and others antennas