This is also covered in this thread. Here's what I wrote there:
Note that if you're at 15% SOC ("0 miles" of range) and you leave the car sitting for six months in extreme (e.g., very much below freezing, or very much above 100-ish F / 40-ish C) temperatures, you still run some risk of killing the batteries. Leaving it for a month should be fine though. Unlike the Roadster, there should be no "parasitic drain" on the li-ion batteries.