Well I sadly joined the ranks of Tesla owners who have run out of charge and need to be flat-bedded to the supercharger. I guess it took over 170k miles for this to happen so I had a good run!
As with most such blunders, there were multiple factors that led to the situation. I left Sunriver, OR with about 150 rated miles remaining. I was headed out to dinner with my family who were vacationing in the area and then headed home afterwards so we were driving separately. I had thought the restaurant was in Sunriver, but it was in fact in Bend, in fact it was quite a ways north of the Bend supercharger. Had I known that I would have left earlier and stopped for a top-off. But at dinner, I figured I could make it to The Dalles supercharger fairly easily so I decided not to back track to the Bend supercharger.
When I routed to The Dalles, the Nav said I would make it with 7% remaining, but that number quickly dropped to 4 and then 3%. Still nothing alarming compared to some of the drives I have done. The sun had just gone down and the temps were perfect for driving with no heat or a/c and of course I had the suspension low and all the other typical hypermiling techniques. There was some wind, which appeared to be more of a crosswind, but it must have had some effect because I was not driving very fast and the percentage kept ticking down to 2, then 1, then 0. Still I have been in this situation many times and wasn't too concerned. I just started driving much more slowly with about 25 miles left in the trip. I had been going 5 over and then right at the speed limit, but now I was going 45 and then 35 in 55 and 65 zones (basically no traffic on this lonely country highway so that was not a big deal).
Now, this leg had a big elevation drop which was one of the reasons I was confident I'd make it, but it is of course disconcerting when you have 25 miles left and only 17 rated miles remaining. Still I knew I had at least a 1k ft elevation drop so I thought I'd be fine. And in fact, by the math, I should have been fine. Right before the car started to shut down it even said I would make it with 1% remaining. At this point I had 5 rated miles remaining and about 7 miles left to go, but I was about to come over the crest of a hill and have an immediate 800 ft elevation drop so I (and the Nav) felt like I would make it without much issue. Unfortunately right before the crest of the hill, I got the warning that the battery was low and I should pull over soon. I kept going over the top off the hill and coasted down it, but at this point I guess the battery was so low that the regen didn't work and this really cost me.
Still, I get to the bottom of the hill and I have 4 miles left to go and 5 rated miles left on my screen, so I attempt to keep going. Again, there's no traffic and I obviously avoid getting on the freeway and stick to the right lane of a country road that is going into the town of The Dalles. The car is still giving me all the warnings to pull over but with 5 rated miles showing, I figure it's worth a shot. I make it about a mile down that country road and 2 rated miles tick off when the accelerator completely loses power, so at that point I coast to a stop on a (forunately) wide shoulder. At this point I was 3 miles from the supercharger and the battery shows 3 rated miles remaining so needless to say I was not pleased!
I was able to get a tow truck in less than an hour and we towed to the fortunately vacant supercharger in the hotel parking lot and I mostly charged without issue from that point on. Still it was not a fun experience.
I guess the moral of the story is to be extremely careful when cutting it close when hills are involved and to not rely on downhill regen at very low SOCs. I had previously driven down to 0 or 1 rated mile remaining on many occasions, often speeding up as I got closer to the supercharger and arriving at 0 or 1 on purpose. I will definitely reconsider this strategy!
Also on this trip, my car was getting very slow charge rates at superchargers. It was different but similar to what I remember with my nerfed S90D. So this was very frustrating and part of me is wondering if this is somehow related to running out of battery early. This was only a brief 4-supercharger trip so I will have to withhold judgment until I make a longer trip, but the behavior was the same at all 4 superchargers so it isn't looking good.
