Published on August 24th, 2016 | by Zachary Shahan0
How The Hell Did Tesla Get The Model S Landboat To Go 0–60 MPH In 2.5 Seconds?
August 24th, 2016 by Zachary Shahan
The Tesla Model S is a big car. It’s in the “large luxury sedan” or “full-size luxury car” class (or, depending on your country and preferred classification, some similar variation that indicates to buyers it is big). It’s a completely unsurprising fact that the only two “production cars” in history that are quicker to 60 mph than the Model S are two-seat sports cars that cost way, way, way more than the Model S P100D. This is a landboat that seats up to 5 adults and 2 children, plus has a ton of storage space. It’s a bit absurd that it’s competing with 2-seat sports cars that cost $1 million or more.
So, how the hell did Tesla achieve such a quick 0–60 mph (0–100 km/h) time? Last time Tesla announced a blisteringly low time to 60 mph (2.8 seconds), it blew people’s minds, and a bunch of commenters said that it would be close to impossible to beat that time with a Model S with street-legal tires.
But Tesla did it.
It’s in the Battery, Baby
When info was unofficially leaking that new Model S P90Ds could get to 60 mph in 2.6 seconds, the only clear explanation we could find was that the battery had changed quite a bit — specifically, it was presumed that the car was housing a 100 kWh (energy capacity) battery that also had more power capacity, and was just being software-limited to 90 kWh energy capacity. It seems that was the case, but the details of how exactly Tesla improved the batteries seems quite complicated and interesting.
“It’s a complete re-do on the cooling architecture,” Tesla CTO JB Straubel said on a media conference call yesterday afternoon in California. “It’s pretty amazing we can do that without changing the external size and shape of the battery pack.”
In other words, Tesla found a way to better cool the battery (and maybe stick more battery cells into the pack), which allowed it to also let more power dart out of the battery when the driver steps on the electricity (time to update our terminology, ya know?).
If you’re still thinking this is pushing things pretty close to acceleration limits, you’re in good company. Tesla CEO Elon Musk added that, with current battery tech, this is “very close to the theoretical limit.”
Hmm, wait, “very close” means Tesla could go ultra low. Furthemore, did you catch that he noted it was the theoretical limit with current battery tech?
Yup, once Gigafactory 1 gets rolling and Tesla + Panasonic are pumping out the new battery cells they’ve designed together (based on “the first principles of physics and economics”), Tesla will presumably be able to do even better on 0–60 times.
The lower limit I’ve seen people claiming is possible with street-legal tires is 2.3–2.4 seconds to 60 mph. This is not my area of expertise, so I won’t insert my own calculations on that, and we’ll all just have to wait to see when Tesla inches lower on a Model S … or a top-of-the line Model 3?
Electric Motors & Batteries & Fuses
But maybe you’re still confused how a 5+2 large sedan can beat every McLaren, every Lamborghini, and all but one million-dollar+ Porsche and one million-dollar+ Ferrari off the line, so let’s keep talking.
As you should well know by now, electric cars offer “instant torque.” Whereas it takes a bit of time for a gasoline car to get to max power, fully electric cars do so almost immediately. (Note that the world’s quickest “production car” is a plug-in hybrid electric car, the out-of-production Porsche 918 Spyder, only 918 of which were produced.)
Nonetheless, that doesn’t make a Renault Twizy as quick as a Tesla Model S, or a Tesla Model S 60 as quick as a Tesla Model S P100D — even if it does make a Smart Fortwo Electric more fun than a Camaro.
Clearly, the motors are part of what makes a car quicker or slower, so I’ll just skip over that bit, but the batteries are also critical.
As we discussed in a previous article looking at BMW i3 vs Tesla Model S batteries, there are various trade-offs when considering which battery technology to use and how to design a pack. Energy density is what most of us are most familiar with — that’s how many kWh of electricity you can stuff into a battery. Safety is another. Cycle life is another. And power density is yet one more.
Power density is basically about how much power can be squeezed out of a battery to propel the car forward. (A bit more specifically, it’s how much power per volume or how much power per weight the battery can output, and it is the volumetric power density that you are typically going to be talking about with electric cars — battery experts, feel free to correct me if I’ve taken a wrong step on this technical cliff.)
As I think you could surmise by now, the 100 kWh batteries being used in P100D Model S sedans (and Model X SUVs) are very power dense. In old-school terms, maybe we could say that they pack a ludicrous number of horses into them.
However, JB highlighted that what they changed was the “cooling architecture.” If a battery is putting out a lot of power, the challenge is handling the heat that comes with that. If the battery pack can’t handle the heat … er, yeah, just don’t go there. So, it seems that what Tesla has done is improve the cooling architecture enough that these extremely power dense batteries can push out more power without overheating the pack. [Update: It has also been suggested that the battery pack is now simply more volumetrically efficient and Tesla has inserted nearly 800 additional battery cells, which together add a bit more power. In other words, it’s maybe not that Tesla is pushing any extra power out of each cell — just that the extra power from hundreds of extra cells is doing the job by itself. This was our assumption last week when writing this article.]
Naturally, Tesla also does a superb job channeling that power from the batteries into the motors and then into the wheels. As reported when the P90D was the hottest kid on the block, Tesla actually took a page or two from the rocketship industry and put an “advanced fuse” in the powertrain in order to do a better job of that.
In the end, no other passenger car in the class of the Model S and almost no other “production car” in history matches the quick acceleration of the Model S P100D because of the large sedan’s motors, batteries, and certain other elements of the powertrain that help to quickly move power from the batteries to the wheels. (If you want an even deeper dive on any of this, let me know and I’ll see if a genuine battery expert can get into more of the nitty gritty for CleanTechnica readers. I’ve also reached out to Tesla to see if an expert can provide more commentary on the matter.)
Tesla Model S P100D Demand
Apparently, there’s a lot of demand for this record-shattering
roller coaster* 5–7 seat sedan, and it’s not entirely easy for Tesla to take back P90Ds from people who want an upgrade, replace the batteries (the 90 kWh batteries need to be removed and recycled), and (the really time-consuming part) build the 100 kWh batteries. This is not a matter of dropping a few more coins in the machine.
“We think we can do about 200 cars a week,” Elon said. “We’re working very hard to ramp that up as quickly as possible.”
I wish we could find out how many people upgrade and how many freshly order the P100D, but Tesla doesn’t typically put out such numbers. Though, there’s a decent chance we’ll get a comment from Elon at some point if a high number of people are going for the top-of-the-line product, as it could come through a bit in revenue per car sold and profit margin, and someone may ask about it on a quarterly conference call, or Elon may just make note of the popularity of the option as he’s done the the past with certain versions of the Model S and Model X.
In the meantime, we will patiently wait for a Maximum Plaid Tesla (which I assume will genuinely debut in plaid).