A little late to reply but I think it's worth noting: I read some Tesla article on the M3 that charging between 20 and 80 percent maximizes battery life. My 2017 e-tron was left off, not running, for 6 or 7 months at 0% charge this year and it took a charge after of 31 miles indicated. So, I don't think it's a problem. Also, 0% does not mean zero charge. OBDeleven, VCDS, or ODIS all showed a 21% battery charge during the downtime.