What I would suggest you do is install, or have installed, a battery isolation switch.

Before you leave your car use the switch to disconnect the battery; this should save your battery so the next time you come back it will have sufficient charge to start your car. Obviously when you do get back make sure to reconnect the battery.

Even though the car is not running, there is usually some constant small drain on the battery. This will be from certain engine computers, the memory/clock in the car radio, the GPS system, the security system ….a lot of stuff is just trickling away power. For short durations this isn’t an issue but for “weeks at a time” it can be …as you’ve found out.

Now, completely disconnecting the battery means all those things I mentioned will not be powered. So, for instance, your radio will lose any memorized settings. If the car has a security system it will be rendered inoperative. You may notice the car runs a little differently when you first start driving it as the engine management computer may have to “lean” your driving style. Getting into the car the first time without battery power will mean you need to use the key …not the remote. Make sure there isn’t some security settings you need to adjust for getting into the car using the actual key. Normally the security system should fail safe to allow manual key entry to the vehicle with a dead battery. Also the hood release is typically manual as well. So weigh all this against having to deal with a dead battery first cat when you get to your condo.