Not riding my AK 550 much during the winter but the thought of having to jump start it when it warms back up would be such a pain. So I picked up a battery tender from Amazon on Cyber Monday and it was easy to install and fits actually quite perfectly in the right side dash compartment.
NOCO GENIUS2D, 2-Amp Direct-Mount Onboard Charger, 12V Automotive Car Battery Charger, Battery Maintainer, Trickle Charger and Battery Desulfator with Temperature Compensation
https://a.co/d/68L1ZagYou just need to remove the windshield, battery access panel, and run the wires thru the dash compartment where the bottom hinge is to the battery (have a wire coat hanger to grab the wires from the top of the battery compartment access) and best part, no drilling required!
It fits sideways perfectly in the compartment when not in use (see pics).