Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Why can't this be done?


  • Please log in to reply
11 replies to this topic

#1 David Brown OFFLINE  

David Brown

    I said I work on them. I never said I fix them!

  • Senior Member
  • Contributor
  • Member No: 8570
  • 4,217 Thanks
  • 2,314 posts

Posted January 21, 2016 - 04:51 PM

If you don't know something, ask someone who is smarter than you.  That's why I always come here and I have a question that has been bothering me for a while now involving electric cars.  In a gasoline or diesel car, the battery is always being charged as the car runs so that it's always ready to go when you hit the key (at least theoretically).  However, electric cars run so long and die until they can be charged again.  My question is, why can't they develop a charging system for these cars?  They could run forever without stopping for a charge.  I bet they would catch on a lot faster too.  I am not an electrical guy (I know, shocking) but I am guessing it's one of two reasons.  1. It would take entirely too much juice to charge all the batteries in one of those cars.  More so than a portable unit could put out.  Or 2. Nobody would be making any money off of these cars other than the manufacturer (read that as not the electric company or the government).  Am I close?


  • oldedeeres and chieffan have said thanks

#2 MiCarl ONLINE  

MiCarl
  • Senior Member
  • Member No: 75926
  • 825 Thanks
  • 472 posts
  • Location: Livonia, MI

Posted January 21, 2016 - 05:02 PM

They have.  That's what a Hybrid is.  Of course the problem is you're using a gasoline engine to charge the battery which doesn't let you achieve the goal of eliminating the engine.

 

Here's why gasoline (or diesel) work so well:

 

1 - High energy density.  You can store enough energy for several hundred miles in a 20 gallon tank and it has modest weight.

2 - You can refuel in a matter of minutes.

 

The challenge for electrics is batteries have comparatively low energy density, they are heavy and they take quite a bit of time to recharge.


Edited by MiCarl, January 21, 2016 - 05:02 PM.

  • David Brown, boyscout862, oldedeeres and 3 others have said thanks

#3 Gtractor ONLINE  

Gtractor

    The Tractor Hoarder

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 782
  • 6,582 Thanks
  • 3,898 posts
  • Location: Chillicothe, MO

Posted January 21, 2016 - 05:02 PM

Most electric cars today are "hybrid".  You can drive on the gasoline or diesel engine while charging the batteries. Once the batteries are full you shut the engine off and run totally electric for a while.  Then repeat.

 

The real answer you are seeking is:

 

Nothing is 100% efficient.  If you have an electric motor belted to a generator, they won't power each other.  The motor won't have enough power/torque to turn a generator large enough to power the motor.  Its a "catch 22".


Edited by Gtractor, January 21, 2016 - 05:03 PM.

  • David Brown, KC9KAS, oldedeeres and 4 others have said thanks

#4 Eric OFFLINE  

Eric
  • Senior Member
  • Member No: 41778
  • 987 Thanks
  • 669 posts
  • Location: Wisconsin

Posted January 21, 2016 - 05:04 PM

The answer to your question lies in resistance and friction, as we all know it is not possible to make a perpetual motion machine. When burning gasoline you are spending energy for the alternator to make energy, at a loss I might add. In short due to friction and resistance you can not create as much energy as you spend while making said energy! A good example is a pendulum as it swings it slows ever so slightly due to friction, the energy you used to propel that pendulum can't be recovered so you operate at a loss. This is obviously the extremely short version but you should get the point.
  • HDWildBill, David Brown, boyscout862 and 3 others have said thanks

#5 David Brown OFFLINE  

David Brown

    I said I work on them. I never said I fix them!

  • Senior Member
  • Contributor
  • Member No: 8570
  • 4,217 Thanks
  • 2,314 posts

Posted January 21, 2016 - 05:26 PM

I guess I should have specified "no gasoline" in the mix.  I knew the hybrids were like that.  I don't know, it seems to me that in this day and age of innovation, someone could come up with something that would work.



#6 glgrumpy ONLINE  

glgrumpy

    Getting Out!

  • Senior Member
  • -GTt Supporter-
  • Member No: 8360
  • 6,647 Thanks
  • 6,460 posts
  • Location: Huntington, IN 46750 North East in State

Posted January 21, 2016 - 06:16 PM

Used to see articles on a flywheel run car. Electric motor started huge flywheel laying on side under car floor. Got it spinning and then had enough inertia to keep going with balance and on special bearings OR even riding on air space magneticlaly or ??  You could propel car for a bit, then motor had to come in at times to up the flywheel speed again and then off for more driving. I don't see them anymore. Think problem was finding material that could take a fast spin and stay together and not fly apart like a bomb. Still had battery for motor, but not used constant. Never did see any longevity specs for mileage or such on these proto-types.


  • David Brown and oldedeeres have said thanks

#7 Eric OFFLINE  

Eric
  • Senior Member
  • Member No: 41778
  • 987 Thanks
  • 669 posts
  • Location: Wisconsin

Posted January 21, 2016 - 06:24 PM

Laws of physics would prevent this from being able to happen, resistance and friction are always present and until someone breaks the universe and discovers frictionless bearings perpetual motion will remain a mystery and a figment of all of our imagination and dreams! We continually come up with more and more efficient ways of travel yet will never be able to recover the spent energy it takes to move our conveyance to its location. They even can recover braking energy and add in solar and still are not able to reach that all lofty goal of perfect efficiency, sorry to say it will always take more energy to move than gained from that movement!
  • David Brown said thank you

#8 MiCarl ONLINE  

MiCarl
  • Senior Member
  • Member No: 75926
  • 825 Thanks
  • 472 posts
  • Location: Livonia, MI

Posted January 21, 2016 - 06:30 PM

I guess I should have specified "no gasoline" in the mix.  I knew the hybrids were like that.  I don't know, it seems to me that in this day and age of innovation, someone could come up with something that would work.

 

The energy to charge the battery has to come from somewhere, the laws of physics dictate that you cannot get more energy out of a system than you put in.

 

As pointed out in the comments on perpetual motion - there is no free energy.


  • David Brown and Eric have said thanks

#9 KC9KAS ONLINE  

KC9KAS
  • Senior Member
  • Member No: 10038
  • 4,781 Thanks
  • 4,302 posts
  • Location: Holland, IN

Posted January 21, 2016 - 06:49 PM

I think that would take "perpetual motion"!


  • David Brown said thank you

#10 OldBuzzard ONLINE  

OldBuzzard

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 805
  • 6,480 Thanks
  • 4,633 posts
  • Location: Oberlin, OH

Posted January 21, 2016 - 08:04 PM

... My question is, why can't they develop a charging system for these cars?  ...

 

Actually they do...to a certain extent.

 

They are using regenerative braking, where the motor turns into a generator when the brakes are used.  That does recharge the battery a bit, but that will only extend the life, not do a total recharge.

 

https://en.wikipedia...enerative_brake


Edited by OldBuzzard, January 21, 2016 - 08:12 PM.

  • HDWildBill, David Brown and oldedeeres have said thanks

#11 toomanytoys84 ONLINE  

toomanytoys84

    Aaron

  • Senior Member
  • Member No: 45129
  • 8,227 Thanks
  • 5,069 posts
  • Location: Ohio

Posted January 21, 2016 - 08:16 PM

Top gear did it. They made a total electric car with a diesel generator in the back!

But what you are saying isn't possible. Nothing is 100% efficient. It takes battery power to run the engine. It takes power from the engine to charge the battery.

Regen brakes turns the cars kinetic energy into potential energy(electric stored in the battery)

I wish I could remember the law of conservation of energy. Something about energy can not be destroyed only transferred...so in my mind you transfer the electric into energy to spin the wheels you can't use the same energy to charge the battery. You can use regen breaking to recoup some of that back though.

Edited by toomanytoys84, January 21, 2016 - 08:19 PM.

  • David Brown and oldedeeres have said thanks

#12 karl OFFLINE  

karl
  • Senior Member
  • Member No: 38218
  • 1,032 Thanks
  • 768 posts

Posted January 22, 2016 - 05:01 AM

There is one I have seen on you tube, a guy in china made it. it has a fan blade in the front that spins the generator while in motion. thus never having to be pluged in .


Edited by karl, January 23, 2016 - 08:12 AM.

  • David Brown said thank you




Top