I'm going on a 15 day vacation. I will not have the ability to leave my car plugged in while I am away. Should I be worried about having an empty battery when I return? Anything you'd recommend to keep phantom drain as low as possible?
I have a Model 3 - Long Range.
List of things to do.
I would add that
for checking on car status, you can use the Apple widget without waking the car. It updates every time the car wakes up/updates the servers (which it does on its own as needed).
I'd also turn off WiFi when you leave the car (it will turn back on every time you get in the driver's seat). Make sure ALL USB devices are unplugged or at least turn off TeslaCam (remember to turn back on).
Note that if the battery gets really cold, it will look like it has lost more miles. But this can be distinguished from true vampire drain, because the projected 100% charge will change a lot.
I was recently on a road trip, and when my car was left outside in 30-40 degree temperatures, my 100% projected charge was 298 miles. But for the entire rest of the trip, assuming the battery was nice and warm, the 100% projected charge was 304 miles.
So I followed the steps above and it looked like I lost 6 miles of charge overnight. But actually I had only lost about 1 mile or less. I could tell because I started the night at 92%, woke up to 92%, but had 6 fewer miles in the morning. There was no snowflake symbol (it wasn't that cold).
I have never had an opportunity to test all of the above steps, unfortunately. So no idea if it really works to get really low drain. But it won't be a total disaster if you follow these steps, for a 15 day period, assuming you have a decent charge to start with.