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Published on November 5th, 2018 | by Steve Hanley

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Jaguar Responds To Criticism About I-PACE Efficiency

November 5th, 2018 by  


The Jaguar I-PACE electric SUV is creating a lot of buzz. In many ways, it is the first all electric vehicle that truly challenges the Tesla Model X. Elon Musk has been begging auto manufacturers for years to make competitive electric cars, and as I found out when I drove the I-PACE in Portugal in June, it is a wonderful driver’s car — fast, fashionable, and fun.

Jaguar I-PACE electric SUVIn Europe, the New European Driving Cycle fuel economy testing protocol has been tossed into the trash bin where it belonged. It has been replaced with the World Harmonized Light Vehicle Test Procedure which is supposed to give results that bear some relationship to what drivers can expect in the real world.

Using the WLTP procedure, the I-PACE is rated at 292 miles, but the EPA has rated it as having only 234 miles of range. Considering that the I-PACE weighs less than the Model X, which is rated at 237 miles of range by the EPA with the smallest available battery, questions about the efficiency of the I-PACE have arisen.

German YouTube channel NextMove drove an I-Pace and Model X side by side on a trip along the autobahn and found the Tesla to be significantly more efficient than the Jaguar. Recently, Autocar took a pair of Jaguars on a 139-mile long road trip. At the end of the journey, the car driven in Eco mode had 56 miles left, for a total of 195. The other car was operated in Dynamic mode and finished with 29 miles of range remaining, for a total of 168 miles.

Curious about all the discrepancies reported regarding how far the I-PACE can actually go on a full battery charge, Quartz reached out to the company and got a long and detailed explanation in response. The company was quick to point out that the I-PACE is perfectly suitable for virtually all daily driving duties, plus it has robust off road capability that “the other guys” don’t offer. If you are looking for an electric SUV that can take on the Rubicon, the I-PACE is the obvious choice. It also noted that Top Gear had managed to drive an I-PACE for a total of 292 miles.

“Headline battery figures alone, such as nominal capacity, are not a truly robust engineering measure for the energy available during an EPA test cycle,” the company said. “This will vary based on how deeply you are prepared to cycle the battery’s state-of-charge — a variable very well known and understood to contribute to longer-term degradation of lithium-ion battery packs.”

Nominal battery capacity and drag coefficient are important considerations, but don’t tell the whole story.

“There are very many more key vehicle characteristics which determine range for a given battery capacity, such as inverter, e-machine and transmission efficiencies, wheel bearing friction, brake drag, active air suspension and continuously-variable damping loads, as well as other losses such as HVAC and other 12V electrical system loads.

“In the design of these systems there is always a balance of attributes, such as efficiency, strength, durability and NVH, all of which contribute to whole-vehicle attributes such as range, energy consumption, performance and driveability, vehicle dynamics, refinement and cabin noise.”

Quartz asked rather pointedly whether the electric motors used in the I-PACE are less efficient than those used by other manufacturers. Jaguar responded:

“Presumably this means: does the I-PACE have less efficient motors than the other vehicles you listed? We can’t speak on behalf of other manufacturers, but the I-PACE’s state-of-the-art electric motors were designed in-house from a clean sheet, and we have eight patents pending. The motors use synchronous permanent magnets, and provide greater than 95% efficiency over a wide range of speeds — between 30-150 km/h.

“They are also extremely compact and light. They weigh around 40 kg each. For a machine developing 200 PS and 348 Nm, this delivers exceptional power and torque density. The motor, together with its transmission, weighs just 78 kg yet develops 200 PS — that’s around half the weight of an internal combustion engine of the same power output. For optimum packaging, the motors are hollow, with the driveshafts passing though the center. This brings huge benefits, enabling a low trunk floor for maximum cabin and luggage compartment space, and SUV ground clearance.”

Is the EPA range only applicable if the battery is between 20% and 80% of capacity, Quartz wanted to know? The answer from Jaguar was:

“The I-PACE has a nominal capacity of 90 kWh and the usable capacity is 84.7 kWh. Like the traction batteries in all electric vehicles and hybrids, the I-PACE’s pack cannot be charged to 100% or run down to a real 0% state of charge because this is detrimental to the cell’s state-of-health and therefore the battery pack’s performance and durability. We manage the depth of energy discharge based on a great number of environmental and driver inputs, primarily to maintain cell state-of-health and consistent performance of the pack over its lifetime.

“The battery pack uses state-of-the-art technology, and just like the I-PACE itself, has been engineered and tested to the same exacting standards as every Jaguar and Land Rover vehicle. This is why we have the confidence to protect and reassure our customers by offering a highly competitive 8-year, 100,000 mile/160,000 km battery warranty: the battery must retain minimum of 70% state-of-health within the warranty period.”

Next, Quartz wanted to now if there were constraints in place that would limit charging at 100 kW of power or with the new 350 kW standard expected to be available from fast chargers in the near future.

“As stated above, the I-PACE’s pack cannot be charged to 100% or run down to a real 0% state-of-charge. This is not a constraint: this is because that is inherently detrimental to cells’ state-of-health, which is why every hybrid and electric vehicle battery pack has a management system which prevents this.

“The I-PACE is compatible with 100 kW DC rapid charging, and has been future-proofed to take advantage of further developments in the global charging infrastructure. There is not an explicit link between the usable capacity of the battery and repeated rapid charging. We have engineered the on-board charger and the battery management system to modulate charge rate in order to provide optimum protection for the battery under all conditions and especially at extremes.”

When asked who their battery supplier is, Jaguar waffled a bit.

“The battery pack and its management system is designed and developed in-house by Jaguar Land Rover. The motors are also designed and developed in-house. This meant no compromises. It comprises 432 Lithium-ion pouch cells, using nickel-manganese-cobalt chemistry — the best technology available today for energy density, thermal management, and sustained power. Pouch cells also give us the design freedom we want to determine the battery pack’s overall dimensions.

“The battery pack was designed and developed in-house, but, like most of our competitors, we source the cells from a supplier. As part of our launch process, we do not discuss our suppliers, but we can say that the cells are state-of-the-art and come from one of the world’s leading Tier One suppliers.”

Finally, Jaguar offered a comment on the difference between the numbers for the WLTP standard and the EPA standard. “Range figures– and in the case of combustion engine vehicles, fuel consumption figures — are different for any model when certified to the EPA and WLTP test cycles because the cycles are very different. The same applied to EPA and NEDC figures for any given model.”

Driving an electric car is different than driving a car with a gasoline or diesel engine. I have found in my own experience with a Nissan LEAF that how the car is driven can have a dramatic effect on range. Highway miles take more energy than city driving. Going uphill uses more juice than going downhill. Turning the heat or air conditioner on automatically reduces estimated range by 10%. Using seat heaters and the heated steering wheel can increase comfort without reducing range noticeably. Range on a cold morning is less than when the weather is warm.

Commenting on the Autocar road trip, the editors of Inside EVs summed it up best. “The I-Pace, with its handsome looks and high-performance capabilities, (not to mention off-road bona fides) remains a great EV choice. Like any vehicle, you just need to operate it within its limitations.”

Focusing exclusively on horsepower or torque can blind us to the overall goodness of a vehicle. Cars with internal combustion engines don’t always get exactly the same mileage from one tank of fuel to another. How the car is driven between fill-ups can lead to differences of 20% or more. Gas-powered cars typically get 10% worse fuel economy in winter because refineries use lighter components that promote fast starts in cold weather at the expense of mileage.

Not every Tesla Model X gets 237 miles of range in all conditions. We learn what to expect from a particular electric car by driving it and coming to understand how it operates. Then we adjust our driving behavior to the car. If your focus is on hypermiling all the time, you will miss out on many of the good things that electric cars do better than conventional cars. For some, just having the Jaguar logo on the front will be enough to overcome any concerns about range or charging speed.

If the I-PACE floats your boat, take a tip from Bobby McFerrin: “Don’t worry. Be happy.” More electric cars in the world is a good thing. If everyone was exactly the same as every other one, the world of motoring would be a very dull place.


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About the Author

Steve writes about the interface between technology and sustainability from his home in Rhode Island and anywhere else the Singularity may take him. His muse is Charles Kuralt -- "I see the road ahead is turning. I wonder what's around the bend?" You can follow him on Google + and on Twitter.



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