Running out of charge in an electric car is almost the same as running out of gas in an Internal Combustion Engine (ICE) car. Except gas cans don't help. When I accidentally ran out of charge just outside the Cleveland Supercharger, I learned some valuable lessons that I will share with you right now.
110v wall charger is worthless
Model S is shipped with a 110v adaptor that will plug in anywhere, including most gas stations and behind low-quality furniture stores with redneck truck drivers. The only problem is that the household current coming out of your ordinary NEMA 5-15 plug is barely a trickle of electrons that can't even have the decency to charge a nearly depleted battery to 1 mile of rated range in 5 hours at a Sam's Club gas station.
In normal weather, the household current will charge the car at 4 MPH. But even after 5 hours plugged in, it did not even register one mile on the rated range meter.
NEMA-14-50, however, is perfectly fine. It is 240v @ 50 rated amps (drawing 40 amps for charging) and can give you 22-25 miles of range per hour. Too bad there wasn't an RV park, campground or even ChargePoint within a few miles of where I landed. I could have charged the 10 miles safe margin to get to the SuperCharger in about a half hour. But no.
Tesla Roadside Assistance isn't much help if you run out of charge
I admit it, I didn't read the roadside assistance contract very well. I just figured "What could go wrong?".
Tesla is very dedicated to customer service. The guys on the Tesla Customer Support line were sympathetic, and even looked up my car to tell me how screwed over I was (I had less than 1 mile of range in the super-secret diagnostic mode, and 4 miles back to the Supercharger that I accidentally passed).
However, that's as far as they could go - the next step would be to call one of their affiliate tow trucks. They were polite and patient with my questions, but there was no moving of mountains. I can't remember if I was even quoted an amount for towing, but I'm guessing it would have been north of $100.
I don't really blame Tesla. It's not like GM gives you free roadside assistance when you run out of gas in your Pontiac Aztec. Or maybe they do, I don't know.
Good thing I have AAA.
AAA is your friend
My wife has insisted that we buy AAA every year for the past 20 years. They have towed various ICE cars we've had over the years, in various situations. So, I was glad that I had it for running out of juice.
Ironically, the one time that I didn't have to rely on AAA was when I first got my Prius. I had bought a 2009 Prius and we were on our way back from a trip to North Carolina, on the Florida turnpike to Orlando. I had filled up with cheap gas in South Carolina, and was running on the same tank when I passed the center median service plaza only to notice that the low fuel warning light was on.
In my previous car, a BMW Z3, the low fuel warning light meant that I had at least 20 miles of range left. The Prius, not so much. It ran out probably 3 miles after the warning light came on. Running out of fuel in a Prius is weird. It runs out of gas and the engine stops and the car stops. But you can restart it on battery only power and drive really slow. Since it was warm and at night, I turned off all the accessories, including the headlights and relied only on flashers. I used my iPhone GPS to find the nearest gas station - 3 miles to the east in Dade City.
I was sure we were going to have to get towed, because the battery meter was down to 1 bar, so I went very slowly with the flashers on through pitch black Florida forest. 100% on battery power alone. To my surprise, we actually made it to a BP station, and it was open. That was only the second time in my life I had run out of gas. The first time was a fun story too, but I'll leave that untold for now.
That experience had me tempted to try the same thing in my 0 mile range Model S, but according to the help line, I didn't have enough juice to go very far at all, even at golf-cart speeds. So, I stayed for the tow truck.
AAA is your friend who will make you wait in -7 degrees for 5 hours for a tow truck.
After I calmed down the cop who was about to run me to the hoosgow for "stealing electricity", he expressed immediate sympathy that I had called AAA. He laughed when I told him they quoted me 90 minutes wait for a truck.
Five hours for a bloody tow truck in -7ºF weather? Nope, nope, nope nope. The first guy was scared to tow it, so he found another guy. He had been home napping at 7:00 PM when the dispatch came and probably hit the snooze button 3 times. Neither had seen a tesla before. I showed them the towing instructions from the help guide helpfully included in the online user guide. The second guy agreed to take a shot, and pulled it off without a hitch. (no pun intended)
Rated Range is not your friend
When you are driving 80 MPH in -10ºF, the Rated Range has no bearing on reality. And when it gets close, like in the last 10%, that is when you are most vulnerable.
I kept looking at the rated range and the miles to go until the next supercharger, and it was always fine, until I got about 20 miles out with 20 miles of rated range. That's when panic sets in.
Rated range is rated at 55mph or something like that, and it is not actually estimating your range based on anything other than the benchmark. This means it is wildly inaccurate when it counts.
Have no fear, because there is a better way.
The Energy panel is your friend
There is a pretty cool graph on the Tesla console monitor that shows a lovely line chart of the past usage patterns of the machine.
Here is a hint to avoid the fate of running out of juice before the SuperCharger. It really isn't hard at all if you know what you're doing.
First, set the Projected Range to "Average", which gives you a value based on your current driving pattern. Also, set the Energy Consumption range to 30mi.
As you drive, the Estimated Range indicator will move up and down to tell you how many miles you have left. My goal was to always keep estimated range at least double the number of miles to the next supercharger.
That's it. If you see yourself dipping below double the range, then slow down and ease back on the climate control. Nothing radical, just be a bit more cautious and you'll be fine.
I would drive fairly conservatively (like at the speed limit) until it became clear that I would have plenty of range to make the destination. That usually came at about the half way point. It was then that I could get it back up to 85 and blow past trucks with my "helper detector" scanning for "highway helpers" who would be trying to "help" me by issuing outrageous speeding tickets.
Luckily I met none of these helpers on this trip.
Make the cabin a sauna at the SuperCharger
I thought the heated seats in the Model S were a luxury until someone pointed out that it uses a lot less energy to heat your ass than to heat the whole cabin. Living in Florida gives me scant opportunity to test that thesis, but when driving across what I call the "Transverse Colon of America", one experiences the full fury of the winter vortex. Thanks, Canada.
To make it easier on the range, I would crank up the temperature in the car to "HI" (about 90º) while it was on the SuperCharger. If it is -8º outside, this is not as unpleasant as it sounds. After that, I would turn off the climate control until about halfway to the next charger when it became uncomfortably cool in the cabin, whereupon I would crank it to a respectable 65º. I could even do this remotely from within the McDonalds eating my Big...er... salad.
Most chargers are less than 120 miles apart, which is no problem for a fully charged Model S. The big stretches on my route were between Saint Augustine and Savannah, between Somerset, PA and Cleveland and between Rapid City and Lusk.
In conclusion, if you know what you are doing, there is no reason to have range anxiety in a cross country road trip using SuperChargers. Just keep the "double range" rule of thumb, and you'll be fine.