Yep, typo (corrected).
For this application 3ohm won't matter.
It will drop only ~0.1volt powering the Nano, while ~3volt is available between battery an V-in.
Leo..
True. It's before the regulator. Not much current so not too much heat, either.
Thanks for all the help. I'll get some parts ordered and post here how I do in a week or so. I have a short wife enforced decorating brake in the study!
Everything between Vgs and Vgs(th) is called 'enhancement mode' and will serve as a variable resistor, and will burn off everything else as heat. You need to avoid that area unless you are doing it on purpose.