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Electric Cars

  1. May 21, 2016 #1
    Lets say we have a car with no engine, just a shell. We want to create an extremely efficient electric vehicle. If we have unlimited resources and man power how would you go about making this vehicle?
     
  2. jcsd
  3. May 21, 2016 #2
    I would actually just start with a regular bicycle, strap the "shell" you're talking about on my shoulders like a football player puts on shoulder pads, hook up an electric "alternator" to my pedal wheels to power my headlight and warm my banana seat, and then go on a road trip! :woot:
     
  4. May 21, 2016 #3
    I'm not sure how to respond to that...
     
  5. May 21, 2016 #4

    billy_joule

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    I'd start by throwing the car shell away, it's not a good starting point. The goal of 'extremely efficient' does not coincide with most cars I've seen, they are all too often concerned with 'comfort', 'safety', 'styling' and 'performance' and other such distractions.

    Then, I'd ask for what any good engineering project starts with: a detailed design specification.
     
  6. May 22, 2016 #5

    russ_watters

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    I'm not sure how to respond to that...
     
  7. May 22, 2016 #6
    It appears iv bin to vague. Im looking for answers along the lines of " installing belt that will spin alternators to regenerate some of the energy from the wheels spinning" or "adding solar panels to the roof" i just want too see people creative ideas so lets hear em
     
  8. May 22, 2016 #7

    ProfuselyQuarky

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    DiracPool, if you want to do that, you've gotta eat a better breakfast than what you posted on that running thread :P

    Forget electricity. Go waffle-powered :biggrin:
     
  9. May 22, 2016 #8

    billy_joule

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    Yes, most definitely.

    That sounds suspiciously like a Perpetual motion machine
    https://en.wikipedia.org/wiki/Perpetual_motion
    Which are banned as they have no basis in science.
    https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/#post-3929007

    Unless you mean regenerative braking?
    https://en.m.wikipedia.org/wiki/Regenerative_brake
    Which doesn't improve efficiency at all, it improves fuel economy..

    Well, solar cells have relatively low efficiency (~20%), lower than a regular petrol engine, and lower again than diesel engines, so if your goal is an efficient vehicle then solar is not the answer.
    I'm being pedantic to make a point; in science and engineering we use terms that have precise definitions, this avoids any chance of ambiguity. If you want good answers you'll need to be specific. Your specs well determine whether you end up witha BMW i8, a prius, a tesla s, a bicycle or a solar racer.
     
  10. May 22, 2016 #9
    Okay well lets just start will a platform like a sheet of metal or board of wood. We put a large battery on it that has a full charge. The battery is connected to a motor that will spin 4 wheels ( one on each corner similar to a car). When the wheels spin they will pull on a belt that will spin copper coils inside a magnet field. The energy harnessed by this process will be routed back to the battery. I know this will not be perpetual motion being as that is not possible but it will bring a good amount of energy back into the battery the question would be the energy lost due to friction, heat, etc. What is a good mechanism to compensate for this loss in energy. Would solar panels produce this compensation for lost energy or is there another mechanism that would work better.
     
  11. May 22, 2016 #10

    jack action

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    And where do you think this energy will come from? What is the source?

    The electric motor is connected to the battery and any energy not used to maintain motion will go to your generator that will resend this energy to the battery ... Pretty useless feature. The bigger will be your generator, the bigger will need to be your motor!
     
  12. May 23, 2016 #11
    Electric cars are the future transportation. Because resources of fuel and gas are shrinking day by day. So, therefore, there is a big need of electric energy in the future. The benefit of electric energy is that this is eco-friendly. By the using of electric energy, enviornment is less damaged.
     
  13. May 23, 2016 #12

    CWatters

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    With such a huge R&D effort available it wouldn't take long to invent a super new battery technology allowing a 1000 mile range. The rest is easy.
     
  14. May 23, 2016 #13

    billy_joule

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    The race isn't over yet. The slow recharge times are still a major hurdle, it's a problem some of the competing technology like hydrogen, biofuel, compressed air etc don't have.
     
  15. May 23, 2016 #14

    CWatters

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    Slow recharge times wouldn't be such a problem if the range was much better.
     
  16. May 24, 2016 #15
    I disagree, it would not be useless at all. Think of a situation where you are rolling down a hill and don't have your foot on the gas or brake, your car would be moving due to kinetic energy from potential energy. Obviously the wheels would be spinning resulting the the belt spinning and energy being routed back to the battery. So if your wondering what the source would be you could say it is from our gravitational field in that situation.
     
  17. May 24, 2016 #16

    billy_joule

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    What you described is regenerative braking, Most electric cars already use it, follow the link in post #9 for more info.
    last time I checked it can increase range by up to only about 15% (~0% during highway travel as you rarely brake), you can only capture energy that'd otherwise be lost during braking, this is only a small fraction of the total energy lost during driving so the range increase isn't amazing. Of course, more economical driving habits (eg braking less) prevents this energy loss in the first place so can improve range more.

    The energy source is still ultimately the battery as the batteries energy was required to climb the hill in the first place. (Unless of course the car was built on the hill..)
     
  18. May 24, 2016 #17

    CWatters

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    No need for a separate alternator. The motor itself can be used to generate electricity. As others have pointed out most electric cars already do this, it's called regenerative braking.

    Using a seperate alternator just adds extra weight.
     
  19. May 24, 2016 #18

    jack action

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    Your machine will actually maintain the speed of your car constant while going downhill, because it will remove all the potential energy - that won't convert to kinetic energy - and store it in your battery.

    I have a simpler system to store energy that all my car had: When I'm going down a hill, I don't apply the brakes, the potential energy is converted to a speed increase and voilà, I can coast on free energy at the bottom of the hill until my car speed decreases to its original value. No complex machine, no added weight, no maintenance.
     
  20. May 24, 2016 #19

    berkeman

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    This is nonsense, and your thread is closed. We do not discuss pseudoscience here -- it is on the Forbidden Topics list in the PF rules:

    Please follow the links in the rules to learn more about why you can't get free energy out of your car design. Regenerative braking on the level or downhill when braking does increase efficiency. Trying to get energy out of your motion when going a constant speed on the flat does not.
     
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