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Published on August 15th, 2011 | by Breath on the Wind


BYD E6 and the EV Range Solution

August 15th, 2011 by  

Build Your Dreams E6

BYD Co Ltd (Build Your Dreams 002594.SZ) is on schedule to enter the growing EV market with the E6 crossover in Q2 of 2012, reports senior vice president Stella Li to Alysha Webb of Plug-in Cars.

It is an interesting time in EV marketing as each manufacturer tries to present their technological solution and win EV popularity. Tesla first gave us the sexiest electric vehicle. Nissan is trying to give us the mass-produced EV. GM is telling us not to be afraid. While all the manufacturers are happy to point out how clean these vehicles are to operate, an ever present undercurrent is the vehicle range and vehicle cost. With the BYD E6, we can focus on range issues.

Battery Capacity

A battery manufacturer that has started building vehicles, BYD could be expected to do something special with the battery. At 60 kWh, the E6 battery is almost 4 times the size of the battery in the GM Volt or Mitsubishi I, and it is more than twice the size of the Nissan Leaf battery. At 53 kWh, only the Tesla Roadster battery pack comes close in size. The capacity of the battery, combined with the way in which the car is driven, the efficiency of the vehicle, and the weightof the vehicle, will determine the vehicle range.

Vehicle Efficiency

Most vehicles on the roads today operate using gasoline or diesel. Not only are we dependent upon petrochemicals, but we use these in essentially only one engine design, the Internal Combustion Engine (ICE). Cars with an internal combustion engine require transmissions, due to no torque at 0 RPM. We have to first bring the engine up to speed and then slip the clutch or use a torque converter to slowly transfer power.

Gasoline is a very energy dense fuel, but by the time we measure how much energy reaches the wheels, we find that it is only about 15% efficient. The balance is wasted. Electric motors are far more efficient. Electric motors have great starting torque and an EV will typically have only one fixed gear with a direct connection. The electric car can be over 90% efficient from battery to wheels.

Vehicle Weight

Efficiency is different from fuel economy. Efficiency only tells us how well we are moving the vehicle load with the energy it has available. A heavier vehicle has more work to do than a lighter one. Therefore, it will not get the same fuel economy as a lighter vehicle with the same efficiency. In an effort to increase range, manufacturers try to use lighter vehicles, make them as efficient as possible and then play a bit with “driving modes” that adapt acceleration and regenerative braking.

The E6 is a “crossover,” an SUV built on a car and not a truck chassis. At 4453 pounds, it is a big car. The Tesla roadster, with a similarly sized battery, is only 2723 pounds and is rated at 245 miles on a charge. The E6 does not yet have an EPA sticker but the company is saying it will travel “150 miles using the AC.”

Battery Chemistry

Battery chemistry is important to how long the battery will last, how quickly it can charge, the cost, weight and size. The E6 uses a Lithium Iron Phosphate battery (LiFePO or LFP). These tend to have more life cycles (the number of times the battery can be charged and discharged) than the more standard lithium cobalt oxide batteries (LiCoO2) that are used in consumer electronics. Energy density is, however, lower, which means a heavier and larger battery pack.

A vote of confidence for this chemistry is that GM has just joined with A123 systems, an MIT spin-off that makes batteries with a similar chemistry. The E6 batteries can achieve a 50% charge in 10 minutes and will take one hour for a complete charge. While this sounds great, in order to transfer 60 kWh of energy in an hour, a 240-volt charger would have to be operating at a minimum of 250 amps (most residences have no more than a 200 amp service). If you had 320-watt solar panels on the roof, you would need over 200 of them to provided the needed power in one hour. This is far beyond the rating of present level II charging you might have installed in your home. Tesla also has a high-capacity, level III charger for its vehicle, which charges the vehicle in 4 hours.

–>> Page 2: Supplying Needed Power, 3 Potential Solutions

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About the Author

We share this World; its past, present resources and our combined future. With every aspiration, the very molecules we use for life are passed to others through time and space so that each of us may be considered a Breath on the Wind. This part of the world's consciousness lives in NYC; has worked in law, research, construction, engineering; has traveled, often drawn to Asia; writes on Energy and Electric Vehicle issues and looks forward to all your comments.   "If you would persuade, you must appeal to interest rather than intellect." -- Benjamin Franklin

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  • Anonymous

    We’re creating ‘electric corridors’ right now. Level 3 rapid chargers are being installed along Interstate 5 in Oregon and Washington with the goal of having quick recharge points from Canada to Mexico in a few years.

    Similar installations are taking place in Arizona and Tennessee. The idea is to build some short routes which local EV drivers can use for longer trips, work out any bugs that might be discovered, and then expand across the nation.

    80% recharge in less than 20 minutes.

    Initial EV sales will likely be mostly to multiple car households and the small percentage of people who don’t use personal cars for longer trips. There will be plenty of demand to soak up whatever car companies can produce.

    Then, either battery capacity will increase to give us lighter, affordable EVs or a large portion of buyers will be attracted to PHEVs. Looking at Volt owners to date, they are driving 900-1,000 miles on one tank of fuel. Clearly the GM/Toyota study which found that the majority of driving days were about 30 miles was correct.

    • Breath on the Wind

      Today the EV demographic has to be someone with private charging facilities and who can realisticly use a vehicle with a 100 mile range. We have seen much data that suggest the range fits the usage of 80 to 90% of drivers (eliminating many rural drivers,) but how many of those also have a place to charge the vehicle. This second requirement may tend to eliminate many urban apartment dwellers who could otherwise make good use of an electric vehicle. We might spend a great deal of money building charging stations in rural America but could get more bang for the buck if we electrified roadways in urban areas. It would reach more people and be a cheaper investment as well.

  • Anonymous

    BYD gives buyers one more option. The Leaf is more range limited but should be cheaper so for those who can get by with less range, pick the Leaf. The Volt is not range limited but more expensive. If the BYD can come to market with a 150+ mile range but cheaper than the Volt it should find friends.

    Thing is, I’ve seen price predictions which put the e6 below the Leaf price. If that turns out to be true then we’re going to see lots of e6s on the road. The Leaf, without subsidies, is already significantly less to drive over the lifetime of the vehicle than a comparable ICEV.

    While the e6 may get only a 150 mile rating, data from a year’s worth of e6 data while 50 of them served as city taxis found that range was more like 180 miles. And that’s will mostly rapid charging (which should give only an 80% recharge). And in a climate which is both quite hot and quite cold during the year.

    Curb weight for the Leaf is 3354 pounds. That might be a more realistic comparison than the Tesla two-seater.

    • Ben

      The LiFePo4 battery should provide much greater longivity. I am not a chemist. My guess is that the iron formulation in the battery chemistry may have something to do with this. As another example, the old nickel-iron battery used in the very old electric cars Edison worked on have know to last nearly “forever”.

    • Breath on the Wind

      Each manufacturer seems to be taking a piece of the marketing pie. I have an EV cost article planned but it would be somewhat complex with lots of numbers so I am circling for the time being. The price of the E6 I have seen mentioned is about 35,000USD which would place it between the Leaf and the Volt. http://www.plugincars.com/byd-e6/price The Mitshubi Imiev is already priced at $27900 (below the Leaf) but it has less range.

      I am somewhat skeptical of the Taxi data as we can expect that it was gathered in a crowded urban setting with little open road, highway speed driving. The EPA has a way of significantly knocking the combined mileage. The Tesla EPA sticker gives it only about 130 miles on a charge while real world performance seems to be coming in at 150 to 225 miles with the record around 350.

      Granted curb weight of the Leaf is closer to the E6 but the point was battery size to weight therefore the Roadster with its 53 KW-hr battery was the better example.

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