What's your source for this data?RegGuheert said:Capacity of Li-ion batteries has been improving at a historical rate of 8%/year.
What's your source for this data?RegGuheert said:Capacity of Li-ion batteries has been improving at a historical rate of 8%/year.
Carlos Ghosn has been quoted as saying that is the rate of capacity improvement they are seeing, but I cannot find the reference.donald said:What's your source for this data?RegGuheert said:Capacity of Li-ion batteries has been improving at a historical rate of 8%/year.
Actually, it exactly supports my statement:donald said:That says too little about much.
RegGuheert said:Capacity of Li-ion batteries has been improving at a historical rate of 8%/year.
Go back and read the title of the thread. The Boeing 737 has ONLY ever been fitted with turbofan engines. Any discussion of propellers or piston engines is off-topic.donald said:That is not remotely like an improvement from the Wright bros. 5 kW piston engine to a modern 15,000 kW turbofan.
Much of the range change for the 737 over the years is due to turbofans with much higher [Edit: meant lower, but let's go with better] sfc owing to higher bypass ratios, closer tolerances, improved materials and more precise engine controls (DECUs). Much is due to improved wing design, and the rest due to lighter components. And we shouldn't forget FMS, GPS/INS and improved weather reporting as factors in real-world range.donald said:AFAIK, the specific thrust of the engines has changed very little, the additional range is down to being able to carry more fuel by being bigger.
The comparison with EVs, then, is the Tesla solution - more batteries, bigger car?
donald said:AFAIK, the specific thrust of the engines has changed very little, the additional range is down to being able to carry more fuel by being bigger.
The comparison with EVs, then, is the Tesla solution - more batteries, bigger car?
Not so. There are huge losses in an airplane traveling hundreds of mile per hour. You can increase the range by increasing the efficiency. For instance, Boeing increased the range of the 787-9 by about 1% by improving the laminar flow over the vertical tailfin using a system of tiny holes and a system to blow air out of them to reduce the wind resistance. They have made many aero adjustments to the design of the 737Max to gain a half-percent here and another half-percent there. Over the course of 50 years, thousands of such improvements have been made and the range is improved as a result. Yes, the fuel capacity has increased, but both the take-off weight and the range have increased by a much greater margin.donald said:One way or another, a plane with the same all-up mass at take-off would have much the same range. You wanna squash energy into a smaller space? That'll be more energy storage, then.
None. And this truth is eloquently communicated by my reference story about historical improvements in usable range while making no mention of batteries or jet engines. Simply put, none of us know by what means the range improvements will come about, but I can confidently say that they will happen because that is what the history of technology teaches me.donald said:If you could make a 3 tonne EV out of cheaper batteries and offer it at a substantial discount to a comparable 2 tonne Li-battery car, then what would you do? What difference that it weighs 3 tonnes if it is not substantially less efficient and goes 500 miles?
I'd agree with that, but I do hope that we are not all forced to pay the cost (both cash, and inefficiencies) of large battery capacities if we don't want them. Clearly, 22kWh is plenty for us folks here to have thought 'that makes sense'!RegGuheert said:Simply put, none of us know by what means the range improvements will come about, but I can confidently say that they will happen because that is what the history of technology teaches me.
Agreed. I don't think we'll be forced to do it. The market should provide differentiated solutions given time.donald said:I'd agree with that, but I do hope that we are not all forced to pay the cost (both cash, and inefficiencies) of large battery capacities if we don't want them. Clearly, 22kWh is plenty for us folks here to have thought 'that makes sense'!RegGuheert said:Simply put, none of us know by what means the range improvements will come about, but I can confidently say that they will happen because that is what the history of technology teaches me.
It will be interesting to see what Nissan (and others) do as they have access to a wider array of battery technologies/capabilities.donald said:In reality, you could add 50 miles for every 100kg of extra battery right now. The Leaf chassis wouldn't take much more, but a mid-sized car design/redesign could be easily constructed right now to take an extra, say, 400kg bringing the total to a, say, 250 mile, 60kWh capacity, but at a cost of some extra $20k, probably $30k after additional engineering of a heavier-duty chassis. That's why I think current battery capacity/range is an issue of cost, not technology, and why I'd say a lower cost technology rather than higher specific capacity is likely to win the day for EVs.
Actually, the Insight is only a couple percent better in total drag than both the current Prius and Model S, despite being significantly smaller.JeremyW said:Better aerodynamics is an area where we could seriously see improvements in range of smaller cars. Problem for the traditional automakers is that these aero requirements don't look like the traditional look. Tesla has shown it is possible to create something aerodynamically slippery but still look good. I recently acquired a first gen Honda Insight and that thing is pretty slippery. Unfortunately it was made during a time of very inexpensive gas prices. But something that looks like that with 20kWh under the floor could sell really well, if marketed towards long distance commuters.
http://www.caranddriver.com/feature...ns-performance-data-and-complete-specs-page-7The first-generation Honda Insight has the lowest drag area of any mass-produced car to date: 5.1 sq. ft., the product of its superb 0.25 Cd and its svelte frontal area of 20.4 sq. ft.
Model S DRAG COEFFICIENT = 2.4 FRONTAL AREA=25.4 sq. ft. DRAG AREA (CD X FRONTAL AREA) = 6.2 sq. ft.
You can't use the manufacturer's quoted drag number for reasons quoted in the C&D article. C&D tested the Insight themselves, and in their wind-tunnel it was no-where near 0.25 Cd. Look at the LEAF. Nissan says that it has a Cd of 0.28, but C&D measured 0.32.JeremyW said:25% difference between the Insight and S.
Current production vehicles shipping today already go outside of your range on both ends:donald said:So, all EVs will, and are going to be, in the range 125 to 155 Wh/km.
TonyWilliams with Reg's annotations in RED said:Range at 65mph (100km ground speed) on dry, hard surface level road with no wind or cabin climate control with new condition battery at 70F, battery capacity is "useable" amount, not advertised amount. All ranges are at the maximum permitted charge and all EPA values are also at 100% capacity.
Nissan
LEAF - 4 miles per kWh (250 wattHours per mile) (139 Wh/km) * 21.3kWh = 85.2 miles / EPA 84
GM / Chevrolet
Spark EV - 5 miles per kWh (200 wattHours per mile) (111 Wh/km) * 19kWh = 95miles / EPA 82
Mercedes
B-Class ED - 3.8 miles per kWh (263 wattHours per mile) (146 Wh/km) * 33.2kWh = 126 miles / EPA 104
Toyota
Rav4 EV - 3.4 miles per kWh (295 wattHours per mile) (164 Wh/km) * 41.8kWh = 142 miles / EPA 113
It already is greater than 30% (The least efficient of the four cars above uses 48% more electricity than the most efficient.) and the range of efficiencies will grow over time.donald said:You're simply not going to see the OOM sort of differences in EVs than between, say, a 7mpg Cadillac Eldorado and a 70mpg euro-diesel. It's only ever going to be a max. 30% energy-efficiency difference between the best and worst. So bigger range = more battery capacity. That's all it comes down to.
GM / Chevrolet
Spark EV - 5 miles per kWh (200 wattHours per mile) (111 Wh/km) * 19kWh = 95miles / EPA 82
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