The Tesla Model S Controversy: Understanding the Effects of Temperature on Electric Vehicle Efficiency and Range
by Vivek Gowri on February 18, 2013 4:22 PM EST- Posted in
- Auto
- Electric Vehicles
- Tesla Model S
- Nissan Leaf
The Impact on the Model S
So, how does this all relate back to the Tesla Model S? The basic technologies involved in the Leaf and the Model S are the same - you have an electric motor, a lithium-ion battery, and an electric heater. The Model S is a bigger car with a more powerful electric motor (310 kW), a larger battery (85 kWh), and a more robust electric heater, but they’re all the same elements. So our findings with the Leaf, particularly in the HWFET side of things, are definitely applicable here (which isn’t to say that the numbers will match exactly, for a number of reasons.) The 85 kWh edition of the Model S is claimed to have a 300 mile range by Tesla and is rated at 265 miles by the EPA based on their 5-cycle fuel economy testing. In cold or near-freezing weather, with the heater running, I would not be that surprised to see range fall to something in the 180 mile region.
The world of electric vehicles is still very new to the automotive industry, the tech industry, and the mainstream consumer. This breed of cars is completely different than ones that have come before, and there’s a lot that people are learning and still need to learn about EV technology. Incidents like NYT vs. Tesla (and the previous Top Gear vs. Tesla, which was an outright sham) are just steps along that path. I feel like I am in agreement with Anand here in that the way cars are tested, as we move into the EV age, needs to change radically.
Thanks to Argonne National Laboratory, the Advanced Powertrain Research Facility, and Dr. Henning Lohse-Busch for testing and analysis of the AVTA Nissan Leaf, as well as Kevin Stutenberg for maintaining the Downloadable Dynamometer Database. All graphs and data used in this post are available publically and are courtesy of Argonne National Laboratories.
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tipoo - Monday, February 18, 2013 - link
They really are the single bottleneck on an incredibly wide spectrum of things, aren't they? From cell phones to being able to wean ourselves off gasoline.JlHADJOE - Monday, February 18, 2013 - link
Unfortunately they're the best we currently have.Lithium Ion is certainly miles better than when we were using NiCD or NiMH.
JPForums - Tuesday, February 19, 2013 - link
Well, there are other options. Silver Zinc (AgZn) batteries are safer than Lithium ION / Polymer as they contain no hazardous materials and don't suffer from thermal runaway. Note: Older Silver Oxide cells contain small amounts of mercury.With lithium based batteries, you have to trade off specific energy (Wh/Kg), energy density (Wh/L), and maximum discharge rate. While advanced Lithium technologies might allow them to achieve higher specific energy or energy density than AgZn, they often come at the expense of each other. For instance, Li-Polymer has higher specific energy than Li-ION, but it also has lower energy density and discharge rate. You would have to use more packs in parallel to achieve the discharge rates of Li-ION or AgZn. They also have a more limited life, even when they aren't in use.
AgZn also has to make tradeoffs, but as less work has been put into them vs lithium, the characteristics don't vary nearly as much. Looking at the overall characteristics of any single AgZn cell paints a much more impressive picture when compared to a single Lithium based cell.
Of course, there are still barriers to entry. AgZn has lower cycle durability. Seeing as Li-ION managed to increase their cycle durability from several hundred cycles to over 1200 cycles, I'd expect AgZn could overcome this with a little work. The largest barrier to entry is most certainly cost. Don't know if there is much we can do about it either. Still, if research can improve AgZn by the amounts that it has improved Lithium based cells, they may become worth the cost.
JPForums - Tuesday, February 19, 2013 - link
Also note Silver Zinc > Silver Oxide.Gokimoki - Tuesday, February 19, 2013 - link
Or forget batteries entirely and go for ultra capacitors. We really need to start pumping in the same kind of r&d funding that li-ion gets into UC's. That would pretty much solve issues with EVs. You'll never get the same energy density as batteries, but being able to recharge in seconds to minutes, weigh MUCH less (partially negating the lower energy density), no toxic components, and virtually unlimited (100 000+) charge-discharge cycles more than make up for it.Daniel Egger - Thursday, February 21, 2013 - link
> You'll never get the same energy density as batteries, but being able to recharge in seconds to minutesYou forgot to mention the fact that there's close to zero infrastructure available where you can actually consume that kind of necessary energy to charge in "seconds to minutes". If it was you'd still have the problem that no power grid operator is going to allow these duty cycles. Plus the cables would be massive and the safety mechanisms ridiculously hard to implement. If they'd finally manage to get the range up to the needed levels that would be even harder to do. Will we see single digit minute charges? Possibly. Seconds? Never ever.
That's exactly the reason why I think battery driven EVs are never going to go mainstream.
greevar - Friday, February 22, 2013 - link
You're right. The grid, as it exists, will not support UC powered cars, but that's not a valid reason to dismiss the idea. The power grid is already an outdated design in need of a change; it might be worth making changes that support new power grid topographies and consumption.Rasterman - Sunday, February 24, 2013 - link
Totally false, "stations" could simply have their own ultracaps that are charged overnight or a long period, or some other method of storing a lot of energy, molten salt, giant flywheels, etc.Getting the energy to the car is only an engineering problem. Drive over an automated plug, station detects you are there and automatically debits your card and moves a coupler 4" to mate with the bottom of your car, which feeds directly into your battery, and offloads kJ of energy in seconds. The interface can be whatever is needed, a 5" connector is needed? No problem, its 100% automated and 100% safe.
After electric cars are mainstream trickle chargers can be installed in or on the sides of roads, no physical contact is required, but would probably be more efficient. Thus you would NEVER have to stop and recharge.
The possibilities are endless, anything can be done.
greevar - Monday, February 25, 2013 - link
Like I said, "as it exists".ikkai - Wednesday, February 27, 2013 - link
Hello, I totally agree with you. A recent breakthrough on super capacitors is exactly what is on your mind and it will definitely change our everyday lives. Here is a video explaining the technology http://youtu.be/OtM6XJlynkkFor those who prefer to just read :), a new carbon based energy storage capacity dubbed as "super supercapacitors" can obtain the same energy density as li-ion batteries while having 100,000+ refill cycles, under a minute charge durations and everything else capacitors are good at.
This thing is like a miracle, they produce it by using normal DVD burners! You can even dispose it by using it as fertilizer for plants! If you got hyped up, continue to read at here (extremetech article): http://bit.ly/w6C0rY
p.s. By the way, thanks to the author of the article :)