General

Charging while driving

edited November 2014 in General
I will be the first to admit that I have no clue what I am talking about here so don't yell at me if this is a stupid question.

I know Tesla recently came out with the dual electric motor setup but before they did that I was thinking about the fact that all that rotational energy from the front wheels was essentially being wasted. Would it be possible to, instead of putting a motor in the front, put a generator in the front or run the front motor in reverse all the time so that as you drive you are drawing energy to power the rear motor but simultaneously using the front wheels' motion to generate electricity to recharge the battery. I realize that is basically what you are doing with regen braking, but my question is could you have it do that all the time? Or do the laws of physics just go NO and then proceed to give you a dope slap for even suggesting such nonsense?
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Comments

  • edited November -1
    The irritation was building, but thank you for being open to the answer there at the end. Yes, that would be a violation of laws of physics and conservation of energy.

    Generators don't spin freely with no effort. To generate electricity with them, they have some resistance to turning--it takes force to spin them around. In the application you are talking about, you can't just add a generator and not affect the motion of the car. The generator would slow the car down, or would require you to press the accelerator down harder, using more energy, just to keep up your speed. That is exactly why they use it for regenerative braking--generating any electricity with it slows the car.

    Remember that motors/generators just convert energy from electrical to kinetic or vice versa. The idea you are proposing is some conversions in a closed loop. Battery - motor - car motion - generator - battery. Motors and generators are at best a bit over 90% efficient, so any extra energy that you pull from the battery to put into car motion and then try to grab it back to put back in the battery is getting converted twice, and you lose about 10% each time, so the system would be running itself down just from that, not even considering wind resistance, tire friction, etc.

    So yeah, that's been thought of, but it is called a perpetual motion machine, and it provably cannot exist.
  • edited November -1
    Yup. Your last sentence is spot on.
  • edited November -1
    <i>. I realize that is basically what you are doing with regen braking, but my question is could you have it do that all the time?</i>

    You obviously could do regen while driving just like you can brake while driving, but doing that you would lose a lot more than you gain. You just deplete your battery faster.

    We can't create energy, nor can we destroy it. We can only convert it to different forms. No conversion is ever perfect, so in each conversion you lose some to non-usable forms of energy.
  • edited November -1
    Nothing impossible really .. You will need a car "organism" to do "regen" by letting it feed while it's moving .. sounds like a camel ride :)
  • edited November -1
    On the other hand, if you supercooled the magnets driving the front motor enough to approach zero rotational friction, you could recover nearly all of the energy imparted by the rear motor. This would allow for hundreds of additional miles . . . Omg, someone tell Tesla!
  • lphlph
    edited November -1
    A lot of people here are without proper education in basic physics. Timo is correct.
    A generator is simply a means of converting kinetic energy (energy from movement) to electrical energy which we then usually store in a battery. The process gives off heat (energy) due to friction of bearings etc mostly but other forms as well which results in loss of storable / usable energy during that process. All else being equal the fewer energy covertion steps we have the higher the efficiency of the whole system. No cheating is allowed or will work. This is the result of the law of entropy.
    Therefore this process cannot be even be100% efficient, let alone gain energy from nowhere. This is a zero sum process and some energy always leaks away leaving you with less total usable energy to use than you put in.
    If you want more energy you have to grab it from outside of this local system.
  • edited November -1
    No, it wouldn't. It would allow exactly the miles you get now, minus the penalty of every extra conversion loss you introduced. You can't win. You can't break even. You can't leave the game.
  • edited November -1
    Now if there were a solar panel on the roof of the car.............
  • edited November -1
    Solar panel on the roof, what a great idea! Then you could use the premium interior LED lights without worrying about range! Only during the day though.
  • edited November -1
    This would create a perpetual stopping machine.
  • edited November -1
    Solar panel onto roof, and each street light replaced with 40kW laser that shoots to that solar panel when car goes by.

    That would work, but you have to hope that their aim is perfect every single time.
  • edited November -1
    Just waiting for "inductive" charging....solar powered..My question is...what is the operating voltage of the Tesla battery ? solar panels are limited...say 44vdc...
    ...following Danfos Turbo cor....magnetic bearings...a small trailer...could hold a small generator...charging on the GO...Has anyone put a trailer hitch on a Tesla...In case you are in a prolonged power outage and need to get out of town...solar cowboy
  • edited November -1
    If a charge handle is plugged in the car will not move.

    So no the car is not set up to run off an auxiliary ....power....unit.....
  • Is this usually when someone mentions putting a "sterling engine" on the battery and motor to capture the heat energy? or maybe a power pot? https://www.austinkayak.com/products/15530/Power-Practical-PowerPot-V-5w-Portable-Generator.html?utm_source=feed&utm_medium=cpc&utm_campaign=Shopzilla&scpid=24&scid=scsho1504455&scr=11/

    :) lol.............
  • edited November -1
    Well since the battery only gets to about 30C ta thermoelectric generator won't do anything.
  • Your last phrase is identify on.
  • edited November -1
    Yours isn't.
  • edited November -1
    Kittykitty,

    Huh?
  • edited November -1
    @EmperorTytus it takes energy to cool things. Your freezer doesn't miraculously cool its contents if not plugged in (unless it is super cold outside already and the door is open).
  • edited November -1
    The only thing that gets charged while driving is the driver! Oh and your devices, maybe a cordless shaver which you can use on the highway in autopilot mode!
  • edited November -1
    Cables embedded in roadways charging vehicles on the fly via induction! Problem solved.
  • edited November -1
    Starventure, when we are able to keep up with potholes then we can start talking aboy ripping up 40000 miles of interstates for the convenience of 100000 evs.

    Or not.
  • edited November -1
    About not aboy. Phone. Sigh.
  • edited November -1
    ↑Incoherent nonsense. There is no separate engine, just a battery-driven motor.
  • edited November -1
    Batterybhai you need to be over in the chevy volt forum
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