Does Tesla as well as the rest of the industry estimate the number of miles remaining, based on the Government standard of 55 miles an hour or does each car company use its own parameter for this "best guess"?
The "Ideal" miles, that can be displayed, is based on a steady 55 mph, level ground, etc. The "Rated" range that almost everyone uses is based on the EPA tests and is much more realistic. One or the other of these ranges are shown in the speedometer or dashboard display. There is also a projected range that is shown in the energy window of the central display and that projected range is based on your current driving conditions. If we are going on a trip where range might be an issue, we drive to the rated range, i.e., adjust our speed so that are average projected miles are equal to the rated range and keep both of these numbers above the distance to go, plus any extra miles we needs to save for elevation gains, safety, etc. So far I have found that the energy usage is very predictable and have been able to achieve the EPA 265 mile rated range when we need to. We have found that we can achieve this range driving at 70 mph on the freeway (or slower).
There are two standards of estimated remaining miles available. "Rated" is based on mixed driving, max 265 miles, the new EPA standard. "Ideal" is the 300-mi. 55 mph old standard. (Not sure if it's still available in the latest s/w.) There is also "Projected" based on your recent (5, 15, or 30 mile) driving habits. You can "modulate" your driving to match or improve on any of those, or just ignore them if you've got lots of charge left, and have fun!
I am posting these articles because of their obvious connection to the range issue. In addition I am concerned about battery life as customers such as myself must be concerned with end of battery life behavior. Various companies make Li-ion
batteries and new research faces various issues with the safety of the electrolyte salts that are used, especially in the mobile cell world.
"The problem is that ever more powerful processors and the applications they make possible evoke customer behavior and stress legacy Li-ion chemistries beyond their design specs, especially because of the heat generated and the current spikes and rapid charging demanded. The best-known result is mobile computing as an eternal search for the next power outlet: smartphones that don’t last the day, and tablets that barely do. “Based on analysis of Strategy Analytics’ SpecTRAX database, the average tablet battery provides just 7.5 hours of run time (web browsing or video playback) on a full charge, with no significant increase evident in the last 12 months,”
However there are clear differences between the mobile cell world and the auto rated LI-ion world. For example: (March 2013)
"While Li-ion batteries for hybrid vehicles have enabled that car segment to grow rapidly over the years, the all-electric vehicle has languished as a niche market. This is in large part because Li-ion batteries just don’t have the charge life or short recharging capabilities for them to make sense for most people’s driving habits. The demise of companies that have developed nanomaterials for Li-ion batteries in all-electric vehicles, like A123 Systems and Ener1, underscores just how difficult it has been to get Li-ion batteries to perform at levels necessary to make electric vehicles to take a stronger foothold in the market.
To address this shortcoming, Pulickel Ajayan, professor of engineering at Rice, and his team turned to the well-characterized use of VO2 for cathodes because of their high energy and power density. While vanadium pentoxide has been used in Li-ion batteries, oxides have not been so readily adopted because they have a low electrical conductivity that translates into slow charge and discharge rates.
Ajayan and his team overcame this problem by essentially baking graphene into the VO2, a process that imparted graphene’s high electrical conductivity into the ribbon-like hybrid material that makes up the cathodes. The graphene is able to pass its conductivity to the hybrid material even though the VO2 accounts for 84 percent of the cathode’s overall weight.
The challenge for the researchers was finding the right method for "baking" the graphene into the VO2. In a process described in the journal Nano Letters, the researchers suspended graphene oxide nanosheets along with vanadium pentoxide in water and then heated the suspension for hours in an autoclave. The result was that the vanadium pentoxide had been reduced into vanadium oxide and had taken the form of crystallized ribbons, and the graphene oxide had been reduced to graphene. When characterized, the VO2 ribbons had a web-like coating of graphene and were about 10 nanometers thick, 600 nanometers wide, and tens of micrometers in length.
"These ribbons were the building blocks of the three-dimensional architecture," said Shubin Yang, lead author of the research, in a press release. "This unique structure was favorable for the ultrafast diffusion of both lithium ions and electrons during charge and discharge processes. It was the key to the achievement of excellent electrochemical performance."
As far as performance, the cathodes are capable of holding 204 milliamp hours of energy per gram and remained stable after 200 cycles even at high temperatures (75 degrees Celsius).
"We think this is real progress in the development of cathode materials for high-power lithium-ion batteries," Ajayan said in the press release. "This is the direction battery research is going, not only for something with high energy density but also high power density. It’s somewhere between a battery and a supercapacitor."
Again, 200 cycles does not suggest an eternity.
My aim would be to hear more about what sort of choices were made regarding longevity and safety (where I have come to reversing the conclusion that the less I know the better off I will be, especially with other car companies having recalled millions of cars in the last month, including Toyotas from 2008 forward). I have always had faith in our governmental institutions to cover this territory and allow that "proprietary" information should generally remain as such, but the facts suggest otherwise. Not only have I heard precious little on the subject here, in addition apparently the research just coming to light indicates very little progress in this "niche" area has been made of late. I can not believe that many companies have built EV's and have allowed them to be tested over a ten year period (given the length of time the Li-ion battery in the Model S has been warranted) to see their behavior concerning both percent of charge left in the battery as well as recharging times after 10 years (or is it 8). I will give them the benefit of the doubt as to the use of appropriate materials to eliminate safety concerns and will leave that up to independent research for those interested in that arena. More to come.
Elon addressed alot of these issues multiple times in interviews but it boils down to this. Panasonic makes the cells used in the Tesla battery packs utilizing a special chemistry created specifically for Tesla. Tesla arranges the cells in a Proprietary way inside a pack (roughly 7000 or so) and cools them via a proprietary liquid cooling system. All of this is in addition to each cell being tripple fused creating a system in which all three fuses would need to fail before the cell could have issues related to power.
On top of all this he is so behind the battery pack he has a 8yr unlimited millage warranty.
So I would be as bold as to say the Li-Ion batteries in the Model S are likely to be some of the safest Li-Ion cells available.
I am not sure I follow you completely. Are you thinking progress has stalled in battery technology? Or are you worried about your safety? Or do you think the government isn't taking its responsibility? The last paragraph is a bit confusing.
Here my 2c on the issues you raised.
http://www.greencarcongress.com/batteries/ It is a very active research area and a lot of promising discoveries are made. But most scientific findings of today will find their way to mass production after 2020 or so. What we are seeing now in mass production is based on the scientific discoveries from before the start of this millenium. These time scales are very frustrating. But unavoidable.
Look at the history of the battery. Was there ever a big breakthrough in the past century? The first lithium ion batteries were only marginally better than the (more mature) NiMH or NiCad's of the time. And I can predict that the promising chemistries like lithium sulfur or lithium silicon will initially yield batteries that are only marginally better than the classic chemistries of that time. Most people hope for the breakthrough, while overlooking the steady, incremental improvements that are being made daily. That steady progress over the past 2 decades is what has made the Model S a reality, not some glitzy miracle breakthrough.
How do you feel driving around with 50-100 l of highly flammable liquid stored in a plastic container right under the bums of your back seat passengers? Can it get any worse than that? Up 'till now only 1 car battery has caught fire, and that was because it was left abandoned after a crash test instead of properly taken care of. I wouldn't worry too much if I were you. Even less about the Tesla battery which has small cells and a good cooling system that reduces the risk for a thermal runaway to almost 0. Totally uncomparable to the Dreamliner batteries.
You conclude: "Again, 200 cycles does not suggest an eternity." Do not confuse fundamental scientific research and product developement. In fundamental research a few 100 cycles suffice to get an idea about the cycle life of your new material. The first silicon anodes would almost completely lose their capacity after only 10 cycles or so. So if your new material loses, say, only 5% capacity in 200 cycles, you know you have something promising. And from those 200 cycles, it is quite easy to predict how the battery will behave in the next 2000 cycles.
These limited cycle tests are simply to quickly separate the wheat from the chaff. Product development is a different ballgame. Then you have to go through thousands of full and partial cycles to see how your product handles it.
One final word on EV sales. You quote from the article: "While Li-ion batteries for hybrid vehicles have enabled that car segment to grow rapidly over the years, the all-electric vehicle has languished as a niche market"
Firstly, until a short while ago, hybrids mainly used NiMH, not lithium ion, so it is factually incorrect. It is rumored the next gen 2015 Prius might still have NiMH.
Seconldy, EV's are not 'languishing'. It is a popular tune to sing, and probably comes from the anti-EV crowd that wants to spread some depressing negativity hoping it will turn into a self fulfilling prophecy.
But it couldn't be farther from the truth. EV sales fall short of some overoptimistic sales projections, but if you look through that fog you can see that EV sales are growing fast, faster than hybrids were at the same stage in their development.
It has only been 4 years since the LEAF went on sale. FOUR years! That is a very short time in the 'old' tech arena. People are spoiled by smart phones or software. A new product generation every 6 months. Well, it simply ain't so with cars. EV's are selling extremely well, but it will take a few generations for them to mature into mass market products. A few generations means 20 years.
Range anxiety is not an issue for me. Before deciding to buy a Tesla, I reset the odometer every morning for three months. What I found was that I traveled more than 100 miles only three times: once 108 miles, once 123 miles and once 187 miles. Accordingly, I decided the 40kWh battery would be satisfactory and for the $10,000 difference in price I could occasionally rent a car or drive my wife's car. I picked up my 40 last Sunday and on Tuesday drove it 112 miles arriving home with 23 miles left. A few more miles than usual as I gladly gave a few of my clients "test rides" and yes i stepped on it a couple of times. Never felt any range anxiety at all!
Near as I can tell, "range anxiety" must be a term coined by GM or one of the big oil company's.
Once you drive it, you realize there is no range anxiety. You know the Wh/mi you need to achieve, and you simply adjust your speed to achieve it (obviously, don't set out on a trip needing 400mi from a charge, but 260 is easily achievable).
Andre. Thank you for addressing my concerns and I apologize for the somewhat confusing last paragraph. Simply put, I was concerned about how these batteries will behave at the end of ten (or even 8) years. I assumed, correctly I believe, that since no car company has an EV that has lasted 8 years yet, no one knows for sure how these batteries will behave. And I was focusing on both issues: 1) Safety and 2) longevity. With respect to the latter, could the projections in the dashboard regarding how many miles remain from 8 year old batteries become so skewed as to leave many motorists stranded. DO we know enough about 8 year old battery behavior to answer that question? (Similar question regarding safety). Since many projections were made after these 200 cycle experiments, I simply wondered if we could use this data for 8 year old batteries. Is that clearer?
After 7 months of driving, I don't have "range" anxiety. Instead, I have "supercharger" anxiety. wondering if I have to wait to charge my car. Doesn't happen often (only once).
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