Published on January 7th, 2019 | by Steve Hanley0
A Look Inside The Tesla Cold Weather Testing Facility
January 7th, 2019 by Steve Hanley
All automakers test their cars in cold conditions to see how freezing temperatures affect their operation. Tesla is no exception. It uses a cold temperature testing facility out in the middle of nowhere about 2 hours south of Fairbanks, Alaska. It is a private compound used by the military to test tanks and armored personnel carriers, among other things. Tesla has created its own test track at the site, complete with twisty roads, steep hills, and skid pads that allow its engineers to learn how well the cars handle slippery roads and Arctic conditions.
Photo by Kyle Field, CleanTechnica
Cold weather and electric cars are not friends. Batteries are like people. They are happiest when the temperature outside is between 70 and 90 degrees Fahrenheit. Cold batteries don’t charge or discharge as fast as they do when they are warm. Heating systems eat up a lot of battery power. All those range estimates you see quoted by the EPA are determined by tests conducted indoors at room temperature with the heater and air conditioner turned off.
When a CNET Road Show writer visited the area — the first journalist allowed inside — he found the Model S P100D he was given to make the drive from Fairbanks to Delta Junction where the testing facility is located got about 30% less range than expected. Some of that may be attributed to the Pirelli Sottozero winter tires fitted to the car. Some of it may be due to snow and ice on the road surface. And some of it may be down to the heater working overtime to keep Stevens warm during the journey.
Most people who have driven an electric car in sub-freezing weather would probably not be surprised by the results. My 2015 Nissan LEAF also gets about 1/3 less range when the mercury in my thermometer goes into hibernation during the winter. It’s a common occurrence with all electric cars, one that the manufacturers seldom talk about at the time of sale.
During his time in Alaska, Stevens had a chance to drive a Model S, a Model X, and a Model 3 through their paces on snow and ice. For some of the driving, Tesla engineers turned off the stability and traction control systems that normally protect drivers from hazardous conditions, something owners cannot do themselves. Here’s some of what he had to say:
“With everything off, I cut onto the freshly groomed field of snow at 65 mph and jerked the wheel left and right and then was instantly thrown into one heck of a tank slapper. The car swerved back and forth as I frantically sawed at the wheel to keep up. I tried this maneuver a number of times and maybe caught it twice, but that’s with a decade of high-speed ice driving experience at my disposal. While I mean no offense to your average Model S owner, your average Model S owner would have spun every time.
“Re-enabling the car’s stability and traction controls took a quick reboot and then I went and tried it again. Same speed, same field of snow, and try as I might I couldn’t get the car to spin. I yanked the wheel left and right with all the finesse of a thoroughly endorphin’d Crossfitter and yet the car always kept itself inline, moving quickly enough to miss the imaginary moose, then calmly settling itself.”
Stevens explains that all Teslas have open differentials — the kind that deliver power to the wheel with the least traction. Older readers may recall this is what made driving your mom’s Pontiac station wagon on snowy roads such a challenge. But Tesla uses the brakes on each individual wheel to stop them from spinning. Combining that with precise control of how much torque each motor delivers permits the car to tame the most outrageous slides.
A video popped up on YouTube recently of a Model 3 traveling on an icy road with Autopilot activated. That’s not a smart thing to do — ever! — but you don’t have to be smart to own a Tesla. The car was on the brink of spinning out completely when the Autopilot caught the skid and returned the car to a safe path.
The driver, Eric Lapierre, noted that he didn’t touch the wheel at all. Of course, he shouldn’t have been using Autopilot at all in those conditions, but he proudly posted the video from his dash cam anyway.
Stevens was impressed by how the Model S and the Model X handled the snow and ice. A 30% slope coated with ice down center “resulted in a slow and occasionally unnerving but ultimately clean ascent. With the e-differentials disabled (again, not something you can do at home), the thing started the climb, spun its tires, and then promptly (and rapidly) skidded backwards down the hill.”
The Model 3 Performance, however, blew him away with its ability to tolerate extreme slip angles without spoiling the fun until the car was poised to tip over the edge into a full fledged disaster. “In Track Mode, the Model 3 will let you hang the tail way, way out, getting some properly lurid drifts going before it cuts the fun. Yes, it will cut the fun if you get things too far out of shape, killing the car’s power and automatically deploying the brakes at the appropriate corner. But, the car gives you an awful lot of rope to hang yourself with before it kindly and reliably steps in to lift the noose from your neck.
“By building the Model 3’s control software in-house, Tesla’s engineers have even more ability to vector torque from front to rear both under acceleration and under regenerative deceleration. This means the car can react more quickly and more precisely, again letting you push it that much further before cutting in.” The Tesla engineers told Stevens an upgrade to Track Mode is in the works that will allow the driver to manually adjust the torque split between the front and rear motors. First we’ve heard of that!
Finally, Stevens addressed some issues Model 3 owners in cold climates have experienced — things like frozen door handles and windows that won’t go down when the world outside is frozen. Tesla has addressed the latter with a software update, but a solution to the door handle issue is still in the works. Stevens says, “Every new model has some teething problems. It’s how the company reacts that’s the important thing.”
How Tesla reacts is one of the greatest assets the company has. It doesn’t hide behind legalese or excuses. It steps up and addresses problems in a forthright and proactive manner, often with direct responses from the CEO on Twitter. What was his name again? …