'pih are in a class of their own requiring unique test procedures'
% The public are evaluating with an outdated metric % http://www.torquenews.com/2250/how-epa-determines-electric-vehicle-s-range-not-simple-it-sounds How the EPA determines an electric vehicle’s range - not as simple as it sounds By Luke Ottaway 2014-08-19 One of the most important factors in the consideration of battery electric vehicles is driving range before the battery is fully discharged. The EPA calculates this number using procedures unique to electric vehicles – here is how it works. When the Environmental Protection Agency estimates the fuel economy of a conventional vehicle or driving range of an electric vehicle, the agency emphasizes that the numbers they provide are only estimates and that “actual mileage may vary” based on a wide range of factors. Considering the importance of range to the practicality and perception of electric vehicles, though, it is worth investigating how the EPA arrives at the estimated value. The EPA uses five drive cycles performed on a dynamometer under controlled conditions, which amount to speed traces simulating real-world driving, to determine the fuel economy of conventional vehicles: a city cycle (UDDS or FTP-75), a gentle highway cycle (HWFET or HFEDS), an aggressive higher-speed cycle (US06), an air conditioning cycle (SC03) and a cold-start cycle (cold UDDS). Often only the UDDS and HWFET are run, and correction factors are applied to estimate the effect of the other three cycles. The EPA’s estimates are not perfect, but do a pretty good job of approximating what a reasonable driver should expect and provide a reliable basis for comparison between all different types of gasoline vehicles. How is the process different for electric vehicles? Obviously, battery electric vehicles are quite different from conventional gasoline cars and thus require different evaluation procedures to determine their efficiency and the all-important driving range. (Plug-in hybrids are also in a class of their own requiring unique test procedures, and will not be considered in this analysis for simplicity.) In 2012 the EPA adopted a new strategy for testing the range of battery electric vehicles known as the Multi-Cycle Test (MCT) procedure. This MCT method, from the SAE J1634 standard, uses a single full depletion test to determine range and AC energy consumption for multiple drive cycle types. As the vehicle is driven over several iterations of the standardized drive cycles on a chassis dynamometer, the EPA measures the energy drawn from the battery pack over each cycle. The vehicle’s total usable battery energy (which is obtained by charging the fully depleted battery following the MCT test to its fully charged state, and is not the total energy content of the battery) is then used to determine the electric range for each drive cycle type. Overall efficiency is calculated from the cycle data by accounting for the charging efficiency of converting AC electricity to DC electricity to be stored in the battery. Why not all of the cycles are used to calculate EV range The standard MCT test procedure consists of four UDDS cycles and two HWFET cycles in a specified sequence including mid-test and end-of-test constant speed “depletion phases” which vary in duration depending on the vehicle and the size of its battery pack. At present, only the UDDS and HWFET are required for EPA certification of a battery electric vehicle – if no other cycles are run, as is typically the case, the range and efficiency values are estimated by applying a correction factor of 0.7 to the UDDS and HWFET results to estimate the effect of the three supplementary cycles mentioned above. Additional minor corrections are then applied to the test-obtained values before the final range and efficiency numbers go on the label. But wait, electric vehicles are known to be significantly affected by both warm and cold temperatures - shouldn’t their impact be tested using the specially designed supplementary cycles rather than approximated with an equation? In theory, EPA official Rob French of the National Vehicle and Fuel Emissions Laboratory told Torque News. How to apply the supplementary cycles to directly evaluate these impacts, however, is not yet clearly defined. As Mr. French pointed out, it would be difficult and time-consuming to accurately evaluate the effect of, for example, air conditioning use. In his words: “The AC [SC03 air conditioning] test is meant to capture the initial impact of AC as it works to bring the cabin temperature down after being soaked in the hot sun at 95 degrees,” he wrote in an email. “Once the cabin temperature is stabilized, the AC has to work a lot less hard, and the impact on fuel consumption diminishes. So simply running a [battery depletion] test with the AC on will dilute the impact that the 5-cycle value is intended to represent.” The time-consuming issue comes into play because each proper AC and cold test requires that the vehicle “soak” in the prescribed temperature before the test for up to 12-36 hours in order to obtain consistently accurate results. And as French also mentioned, not much is known about the impacts of AC and cold temperatures at varying battery state-of-charge. Finally, the 5-cycle test procedure was developed specifically for gasoline and diesel vehicles and its applicability to electric vehicles may be questionable. But at the moment it is the best we have, as we remain in the early days of electric vehicles. How the efficiency/range testing of electric vehicles may change in the future The SAE J1634 standard assures that modifications to the MCT test procedure to account for the unique performance of electric vehicles in cold and hot temperatures will be included “in a future revision of this document.” Indeed, the EPA will eventually create a specific new test procedure designed for battery electric vehicles after it has collected far more data on how these vehicles perform under certain conditions. In the meantime, Mr. French told us that the EPA “(intends) to clarify how 5-cycle testing and equations should be applied to EVs” and will provide a guidance letter on the subject to manufacturers sometime in late 2014 or early 2015. Rest assured that although the EPA doesn’t mandate the supplementary SC03 or cold UDDS cycles yet, auto manufacturers do run these tests in vehicle development to assess and minimize the impact of climate control and cold ambient temperatures on their electric vehicles. And the EPA is fairly accurate at predicting real-world driving range even using estimations and correction factors, as the rated range on the Nissan LEAF label (to cite a prominent example) falls roughly in the middle of the widely varying actual range experienced by drivers all over the United States. In short, the process of evaluating an electric vehicle to accurately estimate its efficiency and driving range is not as simple as it may seem. The EPA will use data it collects from today’s electric vehicles to develop better test procedures for a future with more EV models, but for now their method seems to be the best we can do ... [© torquenews.com] http://venturebeat.com/2014/08/21/how-the-epas-bogus-mileage-ratings-are-hurting-electric-car-sales/ How the EPA’s bogus mileage ratings are hurting electric car sales August 21, 2014 Dylan Tweney [image http://venturebeat.files.wordpress.com/2014/08/sample-window-sticker-with-mpge.png Sample car window sticker with MPGe rating / Green Car Congress ] Sometimes, the advantages of a new technology are unclear because people are evaluating it with an outdated metric. Case in point: miles-per-gallon-equivalent (MPGe) ratings for alternative-power cars, including hybrids, plug-in hybrids, and electric cars. This has become clear to me over the past few months since my family started driving a plug-in hybrid. We’re saving an enormous amount of money by driving on electricity instead of gas, but none of that savings was obvious before we bought the car. Traditional miles-per-gallon ratings have been a key part of automobile marketing for decades. Indeed, it’s one of the things that dealers are required to put on the window stickers for new cars. But how do you handle a car that consumes fuel by the kilowatt, not the gallon? The misguided MPGe The Environmental Protection Agency and Department of Transportation addressed this with the MPGe figure, which has been mandatory on window stickers since 2011. But this rating is artificial, and it doesn’t actually help buyers estimate the true impact of buying an electric or plug-in hybrid car. What does it mean that an electric car like the Nissan Leaf has an MPGe of 126 city/101 highway or that the Tesla Model S gets 95? These cars never consume gasoline at all, so those figures are purely imaginary. It’s hard to translate these numbers into a measure of what the economics of the cars really are. More helpful are the figures in smaller print next to the MPG ratings: kilowatt-hours (kWh) per 100 miles on electricity and gallons of gas per 100 miles on gas. But few consumers know this data exists, let alone where to look for it or how to use it. (Complicating things: The fact that this is stated in amounts per 100 miles instead of per mile.) In my case, my family’s new car is a 2014 Toyota Prius Plug-In. In the past few months, we’ve seen an average fuel economy of about 45 mpg, a little off the official efficiency of 50 mpg in hybrid mode. Our driving includes a combination of around-town trips (taking the kids to school, shopping, errands, and so forth) and one long-distance jaunt for a total of about 3,500 miles. In its plug-in, electric vehicle mode, the Prius has an official MPGe rating of 95. Sounds pretty good, right? But what that actually means depends on your use case. Its range on purely plug-in electric power is small: just 10 or 11 miles. That’s not much for most American consumers, but it’s plenty for us most weeks. I commute via bike and train, and my wife works at home, so the car’s main uses are for taking the kids to school and running errands. The upshot: Many days we burn no gas at all, or almost none. We plug in the car overnight, using a standard 110-volt outlet on the porch (as with most electric cars, the Prius charges just fine on household current). Using the Prius’s capability to schedule its recharge for specific hours, we have it recharge in the early-morning hours, before 6 a.m., when the rates are the lowest. What driving on electricity actually costs It takes about 3 kWh to recharge the Prius. At PG&E’s early-morning rates on our tiered plan, that’s about 20 cents to 25 cents’ worth of electricity. (Hint for northern California readers: PG&E offers a special plan for electric car owners, but the rates aren’t actually that good. Its best rates are available through its Time of Use plan, which charges higher rates during the day but very low rates overnight.) As a result, the economic impact is substantial. Ten miles in our old car, a 6-cylinder Mazda minivan that gets 20 mpg at best, takes about half a gallon of gas, which at California’s current gas rates costs us about $2.10, or 21 cents a mile. In the Prius, burning gas, 10 miles costs us about $1.05, or a little more than 10 cents a mile. But on electricity, that 10-mile all-electric range costs no more than 25 cents, or under 2.5 cents a mile. In other words, on a cost-per-mile basis, electricity is roughly one-tenth the cost of gasoline. Clearly, this gives us an enormous incentive to run the car on electricity instead of gas. We’ve been able to save about $60 per month this way. Add in the savings from the increased efficiency on gas-powered driving (compared to our old car) and our savings are over $100 per month, or almost half the cost of the car’s lease. The savings would be less if our daily driving range was longer, as it is for most American families, because the cost of electricity would become a smaller proportion of our overall driving cost. As a result, enhancing the plug-in range will be critical for Toyota if it really wants to sell more plug-in hybrids. Regardless, none of these economic advantages are obvious to most car buyers, since the MPGe rating obscures them. Complexity and opacity rule Adding to the complexity are fluctuating gas prices, introducing uncertainty into the cost-per-mile calculation for internal-combustion driving. And electricity prices are not only variable, they are not at all transparent. You can’t look them up on PG&E’s website. So it is almost impossible to make this calculation until you actually drive the car home and try it out for a while and then look at your utility bill. No wonder electric cars and plug-in hybrids are not taking over. As long as outdated means of measurement obscure their true economic impact, and as long as the market for electricity remains so opaque, few people will be able to figure out whether they’re worth it. If the EPA wanted to make a meaningful difference, it would force some transparency into electricity pricing and mandate estimated cost-per-mile calculations on window stickers instead of MPGe. Better yet, it could create an app that people could use to perform their own calculations based on their location, utility company, and the current price of gas in their area. Or, even better, car manufacturers like Toyota, Nissan, and Tesla could make their own apps to simplify these calculations easier for would-be purchasers. The good news is that electricity-powered driving is very much worth it — if you can buy a car whose range fits your needs. [© venturebeat.com] ... http://www.chicagotribune.com/classified/automotive/chi-545-mpg-unadjusted-adjusted-fuel-economy-story.html 54.5 mpg: Why our measure of fuel economy is wrong August 21, 2014 For all EVLN posts use: http://electric-vehicle-discussion-list.413529.n4.nabble.com/template/NamlServlet.jtp?macro=search_page&node=413529&query=evln&sort=date http://www.laboratoryequipment.com/news/2014/08/salt-bolsters-lithium-battery-life Halide salt Bolsters Lithium Battery Life http://www.columbian.com/news/2014/aug/12/c-tran-electric-bus-extended-test-drive/ C-Tran takes electric bus for extended test drive http://www.prweb.com/releases/how-to-build-a-50mph/electric-bike/prweb12083919.htm How To Build A 50mph Electric Bike Review Exposes Greg Davey’s Guide For Creating A Fast Electric Bike – Vkool.com Davey’s How To Build A 50mph Electric Bicycle step-by-step guide ... http://vkool.com/how-to-build-a-50mph-electric-bike/ Build an e-bicycle with the performance of a motorcycle while $aving$ http://www.sanluisobispo.com/2014/08/14/3195855/cal-poly-to-install-electric-vehicle.html Campus EVSE installations @Cal Poly in SLO, CA + EVLN: 2014 Mitsubishi MiEV> Bargain basement EV {brucedp.150m.com} -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/EVLN-Bogus-EPA-range-ratings-are-hurting-EV-sales-tp4671191.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
