Model S: My first service visit–planning

Every couple of weeks when I turn on the car I get a message that says: “Driver assistance features not available” and none of the Autopilot features work. The condition lasts for the duration of the trip. The message also says to call Tesla if the condition persists, and after 6 incidents, I called Tesla. Eventually they diagnosed the problem remotely from the vehicle’s extensive logging data and determined that the Autopilot camera needs to be replaced.

If this had been my old Toyota Prius, I would have just shown up at the dealership 5.6 miles from my house first thing the next morning, and waited until it was fixed. If the repair extended through lunch, I would have walked half a mile to one of several restaurants or gone shopping. If they didn’t have the part, I’d have to wait an extra day. With Tesla it’s a little more complicated.

Some Tesla owners report online that non-critical repairs like mine take a long time to schedule. In my particular case, the earliest repair appointment was just a week out. My schedule was the limiting factor this time and so the repair is set in two weeks. Instead of 5.6 miles, the nearest Tesla service center is 94.9 miles, and the trip takes an hour and 45 minutes, not considering rush-hour traffic in Charlotte, NC. Right now Google Maps shows 17 traffic incidents on the route between me and the service center. 😯

The distance to the service center presents an opportunity to discuss a common situation,  an 189.8-mile round trip in Winter in a car that gets 210 rated miles of range in normal weather. The chart below is for a Tesla Model S 70D. It’s in a fact-filled article from the Union of Concerned Scientists: “Do Electric Cars Work in Cold Weather? Get the Facts….”

Tesla Model S 70D highway (65mph) range as a function temperature. Because of its larger battery pack and more efficient thermal management system, the Tesla retains nearly 200 miles of range at 0 degrees Fahrenheit. Data as reported on Tesla Motors website.

I don’t know now what the weather will be like on December 27 [Update: the weather forecast says it will be 43 degrees at 7 am, about the time I will leave home. My Garage will be in the upper 50’s I think.], but presuming it will  be come kind of cold, I think a fair estimate of my range would be 85% or 178 miles, short of what I need for the round trip. Let me hasten to add that this range shortfall is not a big deal. Some amount of charging will be added to the car at the Tesla service center, and there is also a Tesla Supercharger in Charlotte. (Some Tesla models with a larger battery could make this trip easily without charging.) But let’s approach the question more generally and talk a little about trip planning.

Trip planning

There are useful resources for planning a trip. A number of Tesla trip planners exist on the web today:

• A Better Routeplanner
• EV Trip Planner
• EVTripping

Each of these websites allows you to put in travel destinations, and gives you routing; they will estimate how long the trip will take, how much charging you need to do and where. Unfortunately, they all have their quirks. A Better Routeplanner, for example, attempts to minimize driving + charging time rather than just driving time. It’s a cool idea, but the Model S 60 has a completely different charging profile than other Tesla cars, and as a result A Better Routeplanner gives sub-optimal routes for the 60. [Update: ABT has been updated to work  correctly with the S 60.] EV Trip Planner, the most used, can’t distinguish between the old S 60 and the new S 60, and as a result presents incorrect charging time estimates. EVTripping worked best for me in the past, actually having an option to specify a new S 60 car, but it errs by underestimating charging time. All three are still under development and may improve in the future.

There is another route planner, and it’s built into the car. At the current version of Tesla firmware, I think it’s the one I’d choose to rely on. It’s limitation is that waypoints can’t be specified and you can only start the route from the car’s actual location. When I gave it the service center location, it estimated that I would arrive back home with 0% charge.

One of my guilty pleasures is watching Bjørn Nyland videos on YouTube. Bjørn is a Tesla owner in Norway who is actually making a living creating videos and delivering stuff around Norway in his Tesla. Trip planning is a  frequent topic in the video series as he travels around Norway and beyond, and it is interesting to see how he approaches the problem. He uses the car trip planner to estimate the  range needed, and then adds to the needed range things like elevation, temperature, precipitation, speed, cargo load, road conditions and wind. Some of the other trip planners let you specify some of those, but none compensate for all. Some planners work in the car web browser and some don’t.

This brings up a problem with some of the trip planners: you don’t know what factors they are considering. For example, A Better Routeplanner considers current temperature, but you wouldn’t know that just looking at it. EV Trip Planner is the most transparent and comprehensive of the trip planning solutions, but it doesn’t consider precipitation and road conditions (wet, snow).

Bjørn has developed some rules of thumb that he uses to compute the range he will need, and uses a trusty pocket calculator to do the arithmetic. He got those rules from experience, and I believe that I need to start recording details about my trips so I can see how conditions actually affect my car, and what my real range is.

Elevation seems to be the most difficult to compute. The energy required to climb a hill is simple physics, but in real life one goes up and down hills in between start and destination. The car recovers (regenerates) energy coming downhill, but not all of it. I don’t have an authoritative number, but I’d say the total loss is around 40%. EV Trip Planner says the total up and down between here and Charlotte is 3940 feet (but the net is only –171 feet!) and I need 115 rated miles.

Notes

They estimate that the repair will take 3 hours. My appointment is at 9AM and I’ll try to be on the road by 7. I don’t know how much charge I’ll get at the service center, so I’ll plan a swing around to the Supercharger, which unfortunately is on the other side of town.

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