I have a late September, 2016 S75. On Saturday I got the "12v battery needs replacement" warning on the dash. I called the Marietta, GA service center as soon as I noticed the message Saturday morning but no one picked up the phone. So I tried again today (Monday) and got someone on the phone. I expressed concern about the 12v battery needing to be replaced after such a short period. I was told that based on charging habits, it can be quite normal for them to only last this long. His tone was indicative of an improper charging regime. So I mentioned that my car has been plugged in 90% of the time but he still said it's normal. I'm not exaggerating when I say the car has been plugged in 90% of its life. Other than maybe a dozen days we've traveled, the car has always been at home and plugged in when not being driven. Anyway, the tesla guy was just like "well, we have the batteries in stock. when can you swing by?". I pointed out that I live 150 miles from the nearest service center and don't have a break in my schedule large enough for a 300 mile round trip within the next couple of weeks. So now I'm having to pay just about $500 for a ranger to come out and replace the 12v battery. My question is, are these batteries really only designed to last nine months? This car has not been driven hard *at all* and there are no accessories in the car. I've made no modifications, etc. I feel like this battery should have at least made it to my one year service checkup. I had already planned on making the trip for that. Would it have really killed them to give me a break on the ranger fee since the battery didn't even last a year?