Tesla Model 3 Teardown: Deconstructed 3 – Motor Trend
Assessing the underlying engineering of the make-or-break Tesla
It doesn’t take much Googling to locate alarming headlines about the Tesla Model 3. Parts rework rates of 40 percent! Line speeds still less than half of Elon Musk’s promised rate! Never mind the hate-posting on Twitter: Stock price tumbles! Shorts pass $10 billion!
Is this just a case of a niche manufacturer struggling with the transition to high-volume production, or is the Model 3’s essential engineering flawed?
We’re not going to weigh in here on Tesla’s production ramp-up struggles. Rather, we’re going to dig with some folks who are highly qualified to comment on the Model 3’s product and process engineering. In other words: Is the Model 3 a well-made car?
Munro & Associates, Inc. of Auburn Hills, Michigan, is in the business of competitive teardown and analysis. They just completed a 6,000-man-hour study of the Model 3. Scattered around the Munro warehouse is a methodically exploded Tesla, quite literally in pieces. Founder and CEO Sandy Munro highlights the various engineering hits and misses.
Read Tesla’s response to the Model 3 teardown’s results at the bottom of this article.
Best Battery Pack in the Business
The Munro team struggled mightily to disassemble the Tesla pack, so Sandy wonders whether it will be as easy to repurpose for post-EV uses as those in the Bolt EV or BMW i3. The 2,170 cylindrical Panasonic cells in three modules are assembled with remarkable robotic precision. Each individual cell is glued to another and to the cooling channels. A unique low-heat ultrasonic aluminum wire-bonding process connects each cell to the cell-voltage balancing circuitry, which is also exceptionally precise—Munro measured a mere 0.2 millivolt variance between cells. “That’s staggeringly close,” Munro says, “far beyond what anybody else can do.” One curious choice: forming the protected top half of the pack in metal instead of lighter, cheaper fireproof plastic.
Despite aluminum construction of nearly everything aft of the rear bulkhead, the Tesla body structure weighs more than its size peers. That indicates Tesla is trailing the mainstream’s learning curve for stamped and welded/riveted unibody construction. “The strategy for the body is about as bad as could be,” Munro says. “It’s heavy and much more expensive than even the carbon-fiber BMW i3.” A careful study in industry best practices could dramatically slash the body’s cost and weight (benefiting range). One piece of low-hanging fruit: figure out how to assemble the body without an almost unheard-of 165 feet of pumpable body sealant. One flash of brilliance, however, is the instrument panel cross-car beam, an aluminum tube over which the plastic dash mounting structure is molded.
Clearly Tesla employs a lot of savvy electrical engineers. Its electronic computing circuitry ranks somewhere between that of a cellphone and a Mars mission in terms of sophistication. “The controllers are much, much more advanced than anything we’ve seen, and they’re all in one location,” notes Munro of the consolidation of three or four modules to one devilishly complex circuit board. Solderless connections and extreme miniaturization might help realize cost savings (these boards are even smaller and more dense than the Model X’s), but Munro’s cost analysis on the electronics is incomplete. Another savings—where Models S and X use a Tesla-proprietary touchscreen, the 3’s is closer to a commercial laptop touchscreen.
Assembly Quality Lapses
Munro purchased two Model 3s; the teardown is of the one built in January 2018 but delivered in February due to rework. The other was built later. Panel gaps are inconsistent around the same car as well as between cars. Many gaps exceed accepted norms for any price class, though the later car shows signs of improvement. Where the hood meets the left fender on the newer car, the shapes are mismatched, suggesting either a stamping problem or an attempt to bend the hood to match. Shut either front door with the window rolled down, and it rattles. The earlier car also had an extra piece of weather stripping glued to the driver-side front window track. (This was the only example of obvious rework.)
The appealingly spare look of the Model 3’s dash is made possible in part by the lack of normal air vents. The ducting that aims that narrow, nearly invisible cross-car vent is unique in the car business. The air exits vent horizontally and attach to the dash to strike occupants low on the torso. Aim the vents up via a touchscreen command, and a second column of air blows vertically out of the less obvious slit just ahead of the mostly horizontal wood strip. Depending on the velocity of this air, the main airflow aims upward a little or a lot.
Is the Model 3 Profitable?
As we go to press, Munro’s final cost analysis is still a few weeks away, but preliminary analysis suggests the high-content variants being pushed now might indeed break even or make a slim profit. But the standard-battery model starts at $36,000. Can enough money be saved on base models to make them profitable? “There’s nothing here that says ‘save money,’” Munro says. “I think $36,000 Model 3s will be rare as hen’s teeth. I don’t see how they could make money at $36,000.”
Is the basic engineering sound?
Tesla nails the Silicon Valley electrical/electronics engineering better than any current competitor Munro has studied, and his team has scrutinized all the leaders. There’s also abundant and impressive innovation in this car. But its essential body structure and design-for-manufacturing engineering trail the industry. It might be time for Tesla to raid mainstream automakers’ senior mechanical and manufacturing engineering ranks.
Find out how quick the Tesla Model 3 is from 0-60 mph right here.
Statement on vehicle age
“The primary car evaluated by Munro was built in 2017. We have significantly refined our production processes since then, and while there’s always room for improvement, our data already shows that Model 3 quality is rapidly getting better.”
Statement on panel gaps and offsets
“Since we began shipping Model 3 last year, we have been very focused on refining and tuning both part and body manufacturing processes. The result being that the standard deviation of all gaps and offsets across the entire car has improved, on average, by nearly 40%, with particular gap improvements visible in the area of the trunk, rear lamps and rear quarter panel. Today, Model 3 panel gaps are competitive with Audi, BMW, and Mercedes models, but in the spirit of relentless improvement, we are working to make them even tighter.”
Statement on body weight/complexity
“The U.S. government found Model S and Model X to have the lowest probability of injury of any cars it had ever tested, and Model 3 was designed with the same commitment to safety. While there’s always room for refinement of cost and mass, which we are already improving, electric cars have unique safety requirements to prevent intrusion into the battery, and Model 3 was also designed to meet the latest small overlap front crash requirements that other reference vehicles may not have. We stand behind our physical crash testing and our computer simulations of it, which have been remarkably accurate, and the safety that they demonstrate. The safety of our customers is more important than any other metric.”
On – 25 Apr, 2018 By Frank Markus
Original article: http://www.motortrend.com/news/tesla-model-3-teardown-deconstructed-3/