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A question about electric cars

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  • 03-01-2015 11:45pm
    #1
    sblythe
    Closed Accounts Posts: 251 ✭✭


    I've been trying to work this out... Electric cars. Why can they not have two alternators? One to keep charge in the batteries, and another to pump more juice into them, to accommodate the extra use the batteries would have over a standard combustion engine car, thus charging them up, I can't see why this wouldn't work, I have been awake for 17 hours mind...


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    #2
    shanew
    Registered Users Posts: 2,777 ✭✭✭shanew


    An alternator on an electric car wouln't make any sense. Energy has to come from somewhere, and the only form of storage in a pure electric car is the batteries. You can restore some power to the batteries using regenerative braking, i.e. turning some of the kinetic energy back in to electric entry using the power motor in generating mode


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    #3
    sblythe
    Closed Accounts Posts: 251 ✭✭sblythe


    shanew wrote: »
    An alternator on an electric car wouln't make any sense. Energy has to come from somewhere, and the only form of storage in a pure electric car is the batteries. You can restore some power to the batteries using regenerative braking, i.e. turning some of the kinetic energy back in to electric entry using the power motor in generating mode

    Could it run off the drivetrain? I'm not sure if it's just me being thick, but it just popped up in my head, maybe if I've slept on it I'll find out why it wouldn't work, lol


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    #4
    shanew
    Registered Users Posts: 2,777 ✭✭✭shanew


    that's regenerative braking, but all that does is recover energy you already had to use from the battery or some other energy source anyway. Regenerative braking is used by pure-electric cars, and hybrids (include 2014 F1 cars), and I think also by Darts and Luas trains...

    Bottom line is the conservation of energy law - no such thing as energy for 'free', always some sort of cost - petrol, battery charge, potential or kinetic energy etc, otherwise perpetual motion machines would work


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    #5
    Seweryn
    Registered Users Posts: 4,487 ✭✭✭Seweryn


    sblythe wrote: »
    I've been trying to work this out... Electric cars. Why can they not have two alternators? One to keep charge in the batteries, and another to pump more juice into them, to accommodate the extra use the batteries would have over a standard combustion engine car, thus charging them up...
    Why would you need two alternators, rather than one doing the same thing?
    And what about four alternators, one on each wheel?


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    #6
    Dexter1979
    Registered Users Posts: 195 ✭✭Dexter1979


    Altenators are used to generate AC power. Electric cars run on DC power. You can't store AC. There is no alternator in an electric car.

    http://en.m.wikipedia.org/wiki/Alternator

    Get some sleep :)


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    #7
    shanew
    Registered Users Posts: 2,777 ✭✭✭shanew


    Petrol Cars have alternators, with built in rectifiers.. so produce a DC output. They're more efficient than dynamos


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    #8
    TheChizler
    Registered Users Posts: 9,439 ✭✭✭TheChizler


    No, what you do is you run the gas off the electricity and the electricity off the gas and you'll save over £200 a year.


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    #9
    zerohero2015
    Registered Users Posts: 7 ✭zerohero2015


    To generate any decent kilowatts to charge a EV battery you need a big dynamo. The motor of an EV does this when coasting or braking. As a poster said you cant get energy for free, you must use some to generate some.


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    #10
    reboot
    Registered Users Posts: 1,460 ✭✭✭reboot


    zerohero2015 wrote: »
    To generate any decent kilowatts to charge a EV battery you need a big dynamo. The motor of an EV does this when coasting or braking. As a poster said you cant get energy for free, you must use some to generate some.

    I think regen braking is confusing people, braking in this case is more akin to engine braking in an ICE vehicle although some EVs receive current from the actual brakes, but not a lot.
    It may be useful to check the Zoe motor/generator details on the net. I often find I am driving the Zoe at 50 mph, with my foot on the throttle pedal and the battery is charging, going down a slight slope. Hope this experience is of some help? It does change the way you may drive, if you drove a petrol car at a speed that put fuel into the tank, how weird would that seem?


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