I just got back from a very exciting airport experience with my 100D Model X (3k miles or so on it at the time of this posting).
I was away for about six days, leaving Sentry Mode on in an outdoor, about 50-60 degrees, airport parking lot. My battery was reading at 79% when I parked it. The first thing I noticed was the manual on the Tesla talked about Energy Saver Mode, which was for some reason not to be found anymore on my display. No button. No mention of it except in the manual and in a little bit of googling, but I figured a few days away shouldn't be so bad but it was annoying.
Anyway, as I had never parked the Telsa in the lot and never put it in Sentry Mode that long, I checked back about 12 hours later (once I was sunning myself at some pool) and was shocked to find it to have dropped to 73%! I did a little googling and it should have been 1-3% per day, but that was pre-Sentry Mode. I also read that checking it over my iPhone app periodically was not ideal in that the car might spend energy trying to report its situation so I held back for a whopping 24-36 hours (and even THAT was hard!) and it was at 70%! So it dropped 9% in under two days.
I was getting a little nervous and started doing some quick math and decided that even if it lost 10% a day while I was gone, I would still be at an okay-but-definitely-nervous 10% when I returned. I don't live too far from the airport so I wasn't that worried. Only a little. I also took the advice of many people here and stopped checking entirely. Still, it was always in the back of my mind that maybe things would get better... or maybe not. It didn't ruin my vacation wondering about these things, but my wife would certainly agree that it came up in conversation a bit. Still, we agreed to follow the advice and not check it and I mostly made it to the end of the trip from sheer willpower and trust in the forums, which do not have too many horror stories about bricking the car.
Then I checked it about a day before our trip was over... five days in. Or, at least I TRIED to check it but failed as now I was getting a perpetual failure to connect message on my iPhone app. I was prepared for 30% or maybe 20% (worst case) but I was not prepared for "you'll see when you get there," which is what the car was basically telling me.
More googling... so with Sentry Mode, people seem to agree that it drains the battery faster than normal. Nobody seems to have a percent to reference (and I do not either actually, even after my adventure... keep reading!), but the drain before Sentry Mode was 1-3% a day and I was much faster. Then I saw that the whole car shuts down after it hits 20%, which appeared to be what happened to me. At least that is the only thing that could explain it, so I start googling and reading more and cannot imagine how the car could shut down and not have 10% left when I got there, but my app continued taunting me by showing that it last updated several days ago and then it was only 70%, so I had no idea when it hit 20% or even if that was what happened in the first place.
Fast forward to this evening and we arrived at the car, every member of the family a little bit on edge. I sort of gritted my teeth and hit the trunk button. The trunk went up! We loaded the luggage in the car, but I could tell something was a little bit wrong. The inside of the car was too dark. Nothing was on the displays, either the dash or the touchscreen. However, the gull wings went up, my door opened, the exterior lights came on and even the windshield wipers started up.
I repeatedly put my foot on the break and fiddled with everything I could think of but nothing happened. USB for Sentry Mode was not working but some of the interior lights were. Anyway, I started wondering whether this 12V battery I was reading about was doing most of the work for me but the rest of the car just wasn't responding.
My wife saved the day by suggesting that we call Tesla roadside assistance. So we huddled in the car, which was starting to get warm, filled with "how do we uber home and get back out here tomorrow" nervous energy listening to hold music.
Eric picked up about 2 minutes later, which was nice to not wait so long, asked if we were in the car and safe (which sounded like something they always ask before doing anything else). We said yes and yes and he confirmed that he could not connect to the car either and guided us through a basic "foot on break and hold the buttons above the scroll wheel (but not the scroll wheel itself)" procedure. I'll cut to the chase as this post is extremely long but SOMETHING worked (I held for easily two minutes) after about 3-4 minutes of nervously pumping the break and hitting the scroll wheels too when the dashboard screen lit up followed closely by the touch screen.
Battery level was at 61%.
61%???
None of the math I had thought about for the past several days explained any of this. The car was well above 20% but just totally shut down. Sentry Mode was off (of course, as the rest of the car was too), so I am not really sure what put the car into a deep sleep mode, nor am I really aware of what ultimately woke it up as I am in software development and I can imagine some multi-minute boot sequence going on behind the scenes maybe based on the boot procedure Eric asked me to try. Or it could have been me just jamming on every button I could think of.
I can tell you this, next time I park in an airport lot, I will first try and find a place to plug it in (they were all occupied when I parked it) and I will not be using Sentry Mode until Telsa can confirm what might happen. I will also be checking the app periodically (despite the suggestion not to) as I am just not comfortable not knowing what adventure will await when I return.
