Aux power plug wiring

I have one of those aux power receptacles similar to the ones in cars these days. Mine is from Spruce. Anyone know the convention in wiring these things (i.e., which terminal is positive and which is ground)? The receptacle has a stud on the bottom and a tab welded to the outside of the case. My guess is the stud is the positive and the tab is ground, but I would like to know for sure. I don't want to blow up my my cell phone charger!

Thank you,
Jerry

Plug Wiring

I agree that the stud is positive.

Rv6 FF
N495AB
KEOS

Thanks for the info. I wanted to make sure and get it right as I will be charging my battery from the rear seat aux power plug. It will be wired to my hot batt buss.

Thanks,
Jerry