- Following up our recent article exploring Tesla EVs’ range, Car and Driver visited Tesla to expand on the question of how the EV maker has kept itself at the forefront in the highly competitive electric-vehicle range wars.
- Tesla’s stay-in-control approach, in which it builds most of what it needs rather than source items from a supplier, is part of the answer.
- One of several eye-opening statements: According to Tesla, if you improve motor efficiency by 8 to 10 percent, range will improve by 15 to 18 percent.
In 2012, a small EV startup unveiled its second vehicle. The 2012 Tesla Model S wasn’t as flashy as the Roadster that preceded it, but it was a more practical electric car and it essentially changed how the world sees electrification. The Model S sedan with the largest battery pack—with a capacity of 85.0 kWh—was rated at 265 miles of EPA range. Four years later, a larger, 100.0-kWh pack was introduced, and it was no surprise when the range number jumped up to 315 miles. A larger battery in essentially the same package equals more miles between charges. A no-brainer.
But while the pack remained the same, the range has continued to increase over the years. Car and Driver visited Tesla earlier in September, and they let us in on a bunch more of the details of how it achieves this.
The current Tesla Model S Long Range Plus has an EPA range of 402 miles. That’s an 87-mile increase from when the 100.0-kWh version of the vehicle was introduced in 2016. How it achieves this is closely related to the fact that Tesla is building its own motor, inverter, battery pack, and other items instead of sourcing from a Tier 1 supplier. This do-it-yourself approach allows Tesla to continually tweak those parts to maximize their efficiency.
All Batteries Included
At the core is the battery. Unlike other automakers such as Audi, Toyota, or Mercedes, Tesla gives drivers access to the entire pack capacity. In the Model S, that means all 100.0 kWh are available to the owner, rather than always holding some capacity in reserve in the name of battery longevity. A Tesla engineer told Car and Driver that the company has always offered the entire pack in all of its vehicles. Batteries have a finite life span, and other automakers have decided that as some of the cells die, they will have backups available to take their place. For example, Audi’s e-tron has a 95.3-kWh-capacity pack. That’s a gross number, though: the usable portion of the pack is actually 86.5 kWh.
There are also slight variations in pack capacity, according to Tesla. The company told us that the capacity of a Model S battery lands between 100.0 and 105.0 kWh. During a drive in a Tesla-supplied Model S Long Range Plus, the vehicle gave me a warning that I was at zero available miles and had used 96.2 kWh, but the 102.5-kWh pack itself still had about 6.3 kWh of energy left. Tesla says the system is built to work essentially like a gas tank with a reserve.
The downside to giving drivers the entire pack from day one is that battery degradation is more apparent. There’s no buffer when cells stop working. Tesla offers an eight-year, 100,000-to-150,000-mile (depending on the vehicle model and variant) battery warranty that guarantees the packs retain a minimum of 70 percent battery capacity. Building those packs to last requires partnerships, though.
Tesla’s ties with battery makers LG Chem and Panasonic are well known within the Gigafactorys. The companies work closely to extract as much efficiency as possible out of every cell that goes into a Tesla. But after years of working together, Tesla is branching out to other battery manufacturers, particularly CATL of China, and is likely exploring bringing the entire battery production system in-house for more control. Tesla recognizes that it’s eventually going to hit a wall in terms of how much efficiency it can extract from a battery. Even at that point, Tesla told C/D, it will focus on making its battery denser, using cheaper materials, and driving down the price per kilowatt-hour.
In the meantime, the latest range increase to 402 miles involved a new battery cell chemistry that resulted in higher density. The similar improvements have also permeated the lineup to the Model 3 and Model Y since the start of production. Something that’s possible thanks to close collaborations with its battery partners.
It’s likely more information will be shared during Tesla’s Battery Day event next week. CEO Elon Musk is expected to unveil a pack with a one-million-mile life span and talk about the company’s future of battery development. But again, it’s not all about the battery; the efficiencies that lead to a vehicle with a 402-mile range from a 100.0-kWh pack need to be spread out over the entire vehicle.
Taming the Powertrain
Reducing waste in the powertrain increases range. The more efficient a motor, the more time an EV will stay on the road. Tesla told Car and Driver that the motor in the Model S has gone from 80 percent efficient to 90 percent, with peak efficiency at 94 percent during the EPA test cycles. According to Tesla, if you improve motor efficiency by 8 to 10 percent, the range will improve by 15 to 18 percent.
Tesla also told us that its inverter (which takes DC energy and converts it to three-phase AC for the motor) is 96 to 97 percent efficient. At peak, the inverter is almost 99 percent efficient. Of course, there’s still the matter of converting AC electricity to DC when plugged in to a Level 1 or 2 charger. Tesla didn’t elaborate on that efficiency, which is also dependent on your local electrical infrastructure, but it’s much less efficient than that. The use of an electric oil pump for the gearbox reduces energy usage by only spraying oil when needed. This is in addition to making the bearings and seals more efficient.
A Tesla engineer told us that the company has spent the past 10 years building MATLAB models of where all the energy is flowing. From that, it’s determined where the vehicles experience losses due to inefficiencies. The team then goes in and continually tweaks the hardware to increase efficiency. Additional secondary improvements can be pushed via over-the-air updates.
All of these improvements are added to vehicles when they’re ready. Unlike most other automakers, the company doesn’t keep to a model-year refresh schedule. If the motor is more efficient, it goes in the car when it’s ready along with other tweaks, which is how in the middle of summer, the company announced the Model S Long Range Plus had broken the 400-mile-range mark.
That network connection to the vehicles goes both ways. Tesla has been able to take anonymized data from vehicles and used it to make adjustments to software. It can see how a large section of vehicles are traveling and use that information to help it determine adjustments to future software and hardware iterations.
All of this tweaking and tinkering, trying to squeeze every last bit of energy out components, requires many of the elements used in the vehicle to be built in-house. In other words, Tesla’s efficiencies require being Tesla built. That also extends to keeping those cars on the road.
Supercharging Everywhere
For years, traditional automakers didn’t want to get into the charging business. Tesla went the other direction, building out its own Supercharging network. The team that built the vehicle’s charger actually built the first Supercharger station. With that came the trip planner that was initially built by a vehicle engineer. Combined, it has given the automaker a leg up over EVs from other companies because of the system’s ease of use and the number of locations. In the United States alone, there are more than 1000 of the world’s approximately 1900 stations.
All of these U.S. stations use a proprietary connection. Unlike the rest of the industry, which is moving to CCS DC fast-charging ports, Tesla has gone its own way. While the company would like to be the standard, it was unlikely that would ever happen.
While the first Supercharger added roughly 70 miles of range to a Model S in 15 minutes, the current Model S gains 160 miles in the same time period. Unsurprisingly, Tesla told Car and Driver that the next Model S will support even quicker charging. The company’s current Supercharger V3 supports a peak rate of 250 kW, which is supported by the Model S, Model X, and certain variants of the Model 3. So expect quicker charging coming from either a V4 Supercharger or an update to V3. Expect, too, a supported charge rate above 250 kW coming from the Model S and eventually other models in the Tesla lineup.
All of this translates to an automaker that seems to be leaving traditional automakers behind in the race for better range. During a Car and Driver real-world range drive with a Model S Long Range Plus supplied by Tesla, we drove at 65 mph with the climate control set at 72 degrees and adaptive cruise control on. Our range was 422.7 miles, using 99.3 kWh of the 102.5-kWh battery pack. Tesla extrapolated the data to predict that the vehicle would have reached 430 miles of range before the vehicle had shut down and had to be towed away on a flatbed. That’s an impressive feat for a route that went from Tesla’s Fremont factory down to Soledad, California, and back, twice.
We still need to carry out Car and Driver range testing to know for sure how a Tesla’s efficiency stacks up to other EVs, including other Teslas. Our GPS-certified test runs the vehicles at 75 miles per hour on the same stretch of road used to test both gas and electrified vehicles.
But even if our Michigan test were to yield a lower range (which is a foregone conclusion, as we run the vehicles at a higher speed), Tesla continues to reap the benefits of its early decision to build components in-house to have maximum control over how they run in the vehicle as a whole unit. From the vehicles to the ecosystem that keeps them on the road, Tesla works to make nearly everything work in unison. It’s no surprise that Lucid, which is run by former Model S chief engineer Peter Rawlinson, uses the same strategy.
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Source: Motor - aranddriver.com
