# Electric car hypothetical question **URL:** \ **Category:** In My Humble Opinion\ **Created:** [July 16, 2012, 5:48pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424 "2012-07-16T17:48:23Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![diggerwam](https://avatars.discourse-cdn.com/v4/letter/d/919ad9/32.png) [@diggerwam](https://boards.straightdope.com/u/diggerwam)\ **Post date:** [July 16, 2012, 5:48pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/1 "2012-07-16T17:48:23Z")
Granted I don’t know alot about the technology. But from what I understand the batteries are really the sticking point regarding technology. The batteries are simply big and expensive but all they do is store created electricity so the car can start going. Once the car is going then the generator generates enough electricity to keep the car moving forward. If all this is true what would the car buying public think about going back to a hand crank to get the car started. Some kind of manual manipulation to generate enough energy to start the car, then you wouldn’t need as many batteries on board. Am I nuts? ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [July 16, 2012, 5:56pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/2 "2012-07-16T17:56:25Z")
Eh, NO. Perpetual motion doesn’t exist. In a true electric, the batteries supply all the needed power until the next charging opportunity. You may have been confused by descriptions of fuel/electric HYBRID vehicles. In some of these, the batteries provide a power boost for initial acceleration and hill climbinb, and are eventually recharged by a fuel engine (usually gasoline) driven generator. ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [July 16, 2012, 6:00pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/3 "2012-07-16T18:00:30Z")
> [@diggerwam](#): > > Granted I don’t know alot about the technology. But from what I understand the batteries are really the sticking point regarding technology. The batteries are simply big and expensive but all they do is store created electricity so the car can start going. Once the car is going then the generator generates enough electricity to keep the car moving forward. If all this is true what would the car buying public think about going back to a hand crank to get the car started. Some kind of manual manipulation to generate enough energy to start the car, then you wouldn’t need as many batteries on board. Am I nuts? Regenerative braking and solar panels can generate some power, but not nearly enough to drive the car by itself. A hand crake wouldn’t add much, except perhaps a way to charge a dead battery- but it would probably take far longer to pump the hand crake to generate power to go a certain distance than it would to walk the same distance. ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [July 16, 2012, 6:17pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/4 "2012-07-16T18:17:31Z")
I am interested in the inherent inefficiency of hauling around 2000 lbs. of batteries-how does that make sense? In the 1990’s, there was talk of primary batteries for EVs-something like the zinc-air, or aluminum-H2O primary batteries. You use them once and replace-why is this not being considered? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 16, 2012, 6:20pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/5 "2012-07-16T18:20:11Z")
> [@ralph124c](#): > > I am interested in the inherent inefficiency of hauling around 2000 lbs. of batteries-how does that make sense? In the 1990’s, there was talk of primary batteries for EVs-something like the zinc-air, or aluminum-H2O primary batteries. You use them once and replace-why is this not being considered? Cost and infrastructure limitations. ---
**Author:** ![diggerwam](https://avatars.discourse-cdn.com/v4/letter/d/919ad9/32.png) [@diggerwam](https://boards.straightdope.com/u/diggerwam)\ **Post date:** [July 16, 2012, 6:42pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/6 "2012-07-16T18:42:00Z")
Not perpetual motion but the spinning of the wheels should easily spin a turbine and create energy, no? ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [July 16, 2012, 6:45pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/7 "2012-07-16T18:45:31Z")
> [@diggerwam](#): > > the spinning of the wheels should easily spin a turbine and create energy, no? Laws of physics require that the energy thus generated will always be less than the energy consumed to spin those wheels. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 16, 2012, 6:51pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/8 "2012-07-16T18:51:20Z")
> [@ralph124c](#): > > I am interested in the inherent inefficiency of hauling around 2000 lbs. of batteries-how does that make sense? Just for reference, the Nissan Leaf’s battery pack weighs in at [660 pounds,](http://en.wikipedia.org/wiki/Nissan_Leaf#Powertrain) and the Chevy Volt’s battery pack weighs in at [435 pounds.](http://en.wikipedia.org/wiki/Chevy_volt#Battery) And it makes sense because internal combustion engines have relatively terrible efficiencies; an electric car’s system (from the burning of fossil fuel at the power plant, to electrical transmission, to charging station, to battery, to wheel) doesn’t have to be awesomely efficient to beat them by a wide margin. Add in regenerative braking, which becomes possible when you have on-board energy storage systems (e.g. batteries), and the overall weight of the vehicle becomes somewhat less important than it is if the vehicle is equipped with conventional brakes. ---
**Author:** ![VunderBob](https://avatars.discourse-cdn.com/v4/letter/v/839c29/32.png) [@VunderBob](https://boards.straightdope.com/u/VunderBob)\ **Post date:** [July 16, 2012, 6:52pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/9 "2012-07-16T18:52:59Z")
> [@diggerwam](#): > > Not perpetual motion but the spinning of the wheels should easily spin a turbine and create energy, no? No. I’ve often joked that I should hook the TV to a treadmill generator so my wife would have a reason to get her ass off the couch, but a real life demonstration of a 100 watt incandescent lightbulb powered by a bicycle driven generator puts that fantasy to rest immediately. Quite simply, if you’re going to run a 100 watt load, you have to generate 100 watts. On a more practical level, because of friction and transmission losses, it’s more like 130 watts in to get 100 out. No hand crank mechanism could ever start an electric car. Regenerative braking can feed charge current back into the batteries, but it’s short term only. Batteries must be charged, and the only practical method is via a charging station hooked up to the grid, or a gasoline powered engine. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [July 16, 2012, 7:30pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/10 "2012-07-16T19:30:49Z")
> [@diggerwam](#): > > Not perpetual motion but the spinning of the wheels should easily spin a turbine and create energy, no? NO. What you are suggesting is exactly a perpetual motion machine: Motor turns wheels-\>wheels turn generator-\> generator supplies power to turn motor-\>wash-\>rinse-\>repeat. Due to inefficiency at each step, not to mention aerodynamic drag and power needed to climb hills, the power circulating in this loop falls to zero almost instantly…the car won’t move as far as it would have with no electrical system and free-spinning wheels with decent bearings. It takes mechanical power (rpm x torque) to turn a generator. That means that driving a generator adds drag or braking force to the wheels. This will stop the car. Adding a turbine (??) into the mix would only make things worse. ---
**Author:** ![diggerwam](https://avatars.discourse-cdn.com/v4/letter/d/919ad9/32.png) [@diggerwam](https://boards.straightdope.com/u/diggerwam)\ **Post date:** [July 16, 2012, 7:35pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/11 "2012-07-16T19:35:12Z")
Kinda figured I was missing something. Always hated hated hated science in school. Thanks for not smacking me upside the head and making fun of my ignorance. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 16, 2012, 8:04pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/12 "2012-07-16T20:04:04Z")
> [@diggerwam](#): > > Not perpetual motion but the spinning of the wheels should easily spin a turbine and create energy, no? Have you ever ridden a bicycle? Did you have to pedal on level ground? ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [July 16, 2012, 10:37pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/13 "2012-07-16T22:37:17Z")
> [@beowulff](#): > > Have you ever ridden a bicycle? > Did you have to pedal on level ground? Heck, for that matter have you ever ridden a bicycle with a generator/dynamo-powered light? Compare the amount of energy you had to use pedaling it with the light on (the generator making contact) vs. light off (not making contact.) ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [July 16, 2012, 11:39pm UTC](https://boards.straightdope.com/t/electric-car-hypothetical-question/628424/14 "2012-07-16T23:39:05Z")
> [@diggerwam](#): > > Not perpetual motion but the spinning of the wheels should easily spin a turbine and create energy, no? Lots of good answers already, but I’ll add one more, just another way to look at it: the spinning of the wheels \*could \*turn the generator, or they \*could \*propel the car forward. You can’t get the same amount of energy to do twice as much work at the same time.