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heavy so the big battery pack will not hurt so much in the weight budget. Wrong! Very wrong! More initial weight means more batteries needed in the first pla

by Vik1ng 12y ago

heavy so the big battery pack will not hurt so much in the weight budget. Wrong! Very wrong! More initial weight means more batteries needed in the first places, which means more weight and even more batteries because of that. Reducing weight on electric cars is really beneficial: Less weight => less batteries => less weight => less batteries...

dm2 12y ago
I'm sure weight matters a little but torque is what gets the vehicle moving and regenerative breaking puts more back into the batteries with more weight. Aerodynamics seem to be a more critical factor for electric vehicles. You want the vehicle to be able to cruise while using as little energy as possible, and weight doesn't matter as much for maintaining speed. It's the same reason that most modern trains are electric or diesel-electric rather than pure diesel. Many aircraft tow tractors are also electric these days, and they haul some fairly heavy loads.
- morsch 12y ago
  You realize of course that regenerative braking puts more* back into the batteries for heavier vehicles only because a lot more was necessary to speed them up in the first place?
  - dm2 12y ago
    I do realize that regenerative breaking does not 100% cancel out the energy required to accelerate the vehicle. The Model X will be ~10% heavier and Musk has stated recently that the range is expected to be ~10% less than that of the Model S. In other words, obviously a heavier vehicle will use more power than a lighter vehicle, that's true with any fuel source, but it's a small difference in this case. They could put a battery pack with 15% more capacity in it and the range would be about the same as the Model S, but they're probably going to use the same battery as the Model S for compatibility and manufacturing reasons.
eqdw 12y ago
The tyranny of the battery equation?
- maerF0x0 12y ago
  Its unfortunate that the liquid fuels are so energy dense compared to present battery tech. Adding 1L of gasoline gives a very large marginal gain in range, but adding 1 battery has rapidly diminishing returns. As batteries become more energy dense, we'll probably see people doing silly crap like VW did, big fuel tank and "Look! It goes 1000KM between fuel ups"
barrkel 12y ago
Electric vehicles aren't rockets; much of the energy expended to accelerate can be recovered through braking. The energy required to maintain a given speed is almost independent of weight. Most energy loss at speed is from wind resistance. Rolling resistance will be affected some by weight, but it's not the dominant factor at speed.

by Vik1ng 12y ago

dm2 12y ago

I'm sure weight matters a little but torque is what gets the vehicle moving and regenerative breaking puts more back into the batteries with more weight. Aerodynamics seem to be a more critical factor for electric vehicles. You want the vehicle to be able to cruise while using as little energy as possible, and weight doesn't matter as much for maintaining speed. It's the same reason that most modern trains are electric or diesel-electric rather than pure diesel. Many aircraft tow tractors are also electric these days, and they haul some fairly heavy loads.

morsch 12y ago
You realize of course that regenerative braking puts more* back into the batteries for heavier vehicles only because a lot more was necessary to speed them up in the first place?
- dm2 12y ago
  I do realize that regenerative breaking does not 100% cancel out the energy required to accelerate the vehicle. The Model X will be ~10% heavier and Musk has stated recently that the range is expected to be ~10% less than that of the Model S. In other words, obviously a heavier vehicle will use more power than a lighter vehicle, that's true with any fuel source, but it's a small difference in this case. They could put a battery pack with 15% more capacity in it and the range would be about the same as the Model S, but they're probably going to use the same battery as the Model S for compatibility and manufacturing reasons.

eqdw 12y ago

The tyranny of the battery equation?

maerF0x0 12y ago
Its unfortunate that the liquid fuels are so energy dense compared to present battery tech. Adding 1L of gasoline gives a very large marginal gain in range, but adding 1 battery has rapidly diminishing returns. As batteries become more energy dense, we'll probably see people doing silly crap like VW did, big fuel tank and "Look! It goes 1000KM between fuel ups"

barrkel 12y ago

Electric vehicles aren't rockets; much of the energy expended to accelerate can be recovered through braking. The energy required to maintain a given speed is almost independent of weight. Most energy loss at speed is from wind resistance. Rolling resistance will be affected some by weight, but it's not the dominant factor at speed.