Tesla’s Semi can go as far as diesel trucks, except when Winter’s Coming
[This article is an excerpt from our special report on Tesla’s Semi Strategy: in which we compare operating cost of the electric Semi against diesel trucks, evaluate whether Tesla would make more revenue selling delivery trucks, and analyze risks facing the truck program.]
Drivers forced to sleep
Federal regulations dictate that a commercial truck driver can only drive 8 hours straight before having to take a 30 minutes break. That’s 480 miles at 60mph on the highway. Less than Tesla Semi’s 500 mile range. The driver can then drive for another 3 hours to complete his 11-hour daily driving limit. Adding 180 miles to his daily trip at 60mph. This totals 660 miles a day under ideal conditions (i.e. no traffic and no time wasted loading).
Tesla Semi’s max daily travel range is thus only compromised if its battery fails to allow the truck to cover 660 miles in a day, or when x + 80%*x < 660 miles (where x represents the truck’s max range). This assumes the truck starts the day fully charged and uses the megacharger once to recharge to 80% of its max capacity. Solving for x, we get 367 miles as max range.
At that point, the truck’s battery would only have a max capacity of 73.6% relative to its original state. Way past the battery’s end-of-life. Engineers define end-of-life when a battery’s max capacity drops to 80% of its original state. We expect the Tesla Semi to hit that point after roughly 675,000 miles or ~8 years.
Considering most large trucking fleets replace their trucks after 3 to 5 years to keep maintenance costs low (the average truck operated one of the largest trucking companies, Knight Swift, is only 1.9 years old), most Tesla Semi operators won’t have their max daily range limited by the battery.
“Autopilot, go to the closest megacharger.”
Max daily range will however be limited by location of megachargers. 367 miles is also the minimum distance a Tesla Semi has to travel before needing to use a megacharger to achieve its optimal daily travel distance of 660 miles. The max distance a megacharger can be located from the start is 480 miles, limited by regulations on how long a driver can drive. This means truck operators absolutely need a megacharger located between 367 miles and 480 miles from departure.
This strict requirement in megacharger location may limit the routes on which the truck can drive. Limiting its adoption rate.
Tesla’s megacharger construction plans are still unclear. It appears the first megachargers will be found at regional distribution centers of Tesla partners (likely close to metropolitan regions). Aside from Tesla partners, only trucks operating routes that pass by these stations will be able to complete their journey.
Looking at North American supercharger stations as proxy, their numbers grew 100% annually from 2014 and on. From 50 in 2014 to 361 stations in 2017. Even if megacharger stations grow at this rate, it’ll still be a tiny number compared to the existing 156,000+ diesel stations.
Does this parking spot have an electric outlet?
Finding a spot for Tesla Semis to recharge overnight is another problem. There’s already a shortage of parking spaces for tractor-trailers, with 90% of drivers reporting difficulties finding safe places to park their trucks overnight. Needing an electrical outlet won’t help.
Winter’s coming
Cold weather will also limit the routes Tesla trucks can operate on. According to recent research from Penn State, lithium-ion batteries have reduced capacity in freezing temperatures due to bad charge transfer, low electrolyte conductivity, and reduced solid-state diffusivity. That’s bad news as half of America experiences freezing winters between December and February.
Research by NASA found that the capacity of a Li-ion cell at -20℃ is only 60% of its room-temperature value. To combat this issue, electric vehicles use heaters to actively manage the batteries’ temperature.
Two different sources (Teslarati, Consumer Reports) report a reduced range of ~180 miles in real-life winter conditions for Tesla’s 265 mile range Model S P85. That’s a 30% drop in range. Pushing the battery’s max capacity below 70%. Just enough to compromise the max daily driving range of the truck below 660 miles.
One solution may be for operators maintain a mixed fleet of electric and diesel trucks. Sending the electric trucks south and diesel trucks north in winter months. And the opposite in summer months.
[This article was an excerpt from our special report on Tesla’s Semi Strategy: in which we compare operating cost of the electric Semi against diesel trucks, evaluate whether Tesla would make more revenue selling delivery trucks, and analyze risks facing the truck program.]
