at your condo, do you park in front of your unit? is there power available to the car? i know you ruled out a battery tender but it will solve all your issues and you wont feel pressured to drive the car distances... CTEK 3300 battery maintainers are water proof. If you could get power out to the car you just hook it up to the hood terminals, shut the hood and leave it outside, the unit is sealed.
2011 328 xi coupe