We have a 2012 and in order to power the radio, the key had to be in the second detent/accessory position. Very stupid design so we had it modified to use with the key off entirely. Don't worry about the electrical draw as it is negligible.
Good luck with getting good reception with the POS Axxera radio. I gave up and just stream Pandora via Bluetooth. Next youíll find the speakers are crap as well. I replaced all 4 with Dual speakers. Good luck.