Electric Car Discussion

reply to post by cutbothways




Charging while parked is a good idea, except that if it isn't sunny, you might not make it home. Or if you work at night, it's useless. And solar doesn't add much when you're actually going.

A fan charging a set of batteries will have both aerodynamic and electromagnetic drag, which will amount to far more energy than will actually get charged into the second set of batteries. IE- you'd be doing the same damn thing by using the first battery to directly charge the second battery electrically. And it wouldn't accomplish anything, you'd just be out a sizable amount of electricity lost to heat.

Using the motor as a generators while braking uses the negative aspects of this idea for a positive effect, but it's already widely done in hybrid cars.

Collecting static will do little, and switching to three phase 220v from battery voltage will actually net you a loss in power, unless you can't make as efficient a dc motor as an AC motor. Your currency is energy here, and so it doesn't matter if it's AC or DC, given motors of equivalent efficiencies. It's certainly not going to represent a huge leap in performance, if it increases performance at all. You need 745.6 watts to get 1 horsepower, and your battery provides a certain number of kWh. DC'll take it to the motor just as well as AC, and doesn't require an expensive inverter.


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[edit on 8-5-2008 by Jbird]

Originally posted by Karlhungis
Right now it just feels like the electric cars are only a carrot being dangled in front of our faces to make us feel like progress is being made. I can't think of a single affordable electric car right now. One came out for 25k but that is a pretty absurd price to pay for something that will only go 110 miles/charge and only 65mph.

The tech being used in the cars doesn't seem new at all. We hear of reports of huge strides being made in alternative energy like solar collection, yet these cars don't use it. We hear about strides being made in batteries as well (Japanese Pee battery comes to mind www.reghardware.co.uk...) yet, these still use old tech toxic batteries. The environmental toll of these cars is higher than a standard fuel burning car.

I am jaded and feel like we are all being taken for a ride.

That's rather your problem. The fact of the matter is, most claims about any new technology are overstated. Think popular mechanics. In at least most cases, technology isn't suppressed or anything, it's simply *not as good as advertised, to the point that it isn't useful*. Even if the performance is better, the cost may be prohibitive. Look at the Tesla roadster. It's merely got the best of well developed technologies, like a bank of Lithium batteries, and it's very expensive. Developing all new technologies far enough that they can be safely and reliably used in a car is very expensive.

Ultracapacitors can be charged in seconds to minutes, but they're expensive and don't hold as much energy per unit weight and volume as a battery. Batteries are more advanced than most of the rest of our knowledge of chemistry, but they're still far behind gasoline in terms of energy per weight and volume. Realistic, safe-esque vacuum enclosed kinetic flywheels are only about on par with batteries, but can be charged and discharged much faster, but aren't close to being developed enough for automotive use.

Solar cells are useful for charging cars when idle, but simply can't keep one going very well - there aren't that many square meters on the top of a car, and they're going to be pointing straight up on average, so you'll be lucky to catch 500W per meter square on a bright sunny day, and at about 15% efficiency, 4 square meters of solar panels is going to net you a little under ONE HALF HORSEPOWER (assuming 100% efficient electric motor, which isn't a bad approximation- I've seen ones that reach a 98% theoretical efficiency, for about a 95% actual efficiency.).


Electric cars may not make as much money in dealer repairs, of the engine, but they will have to have all the batteries replaced every six years or so, for a good 2000-6000+ dollars, which a dealer could stand to make a tidy profit on. Dealing with all the dead batteries is a real problem, one of the major obstacles with mass use of electric cars. And they may be far more energy efficient than an ICE, but, because we build few renewable energy stations, and no new nuclear plants, nearly all the extra power is going to come from coal and oil anyway. Combine that with the fact that energy companies will probably just buy battery makers.

And they may make overall economic sense, but the average American does not want, nor can afford, such a vehicle. They have a strict limitation on range, limited performance, a very high initial cost, and an inconvenient refuel cycle. Fuel economy is like the 12th highest concern, or something ridiculous like that. People loved that Rav4 electric car, or whatever it was called, but you'll note that the people who loved it were the kind of people who'd buy electric cars, not necessarily representative of people on the whole.

Despite all that, there are plenty of affordable electric cars on the market, they're just not highway capable. The government owns thousands of 'em, as fleet vehicles. They even sell 'em at costco sometimes. Ugly little things though.

reply to post by Apex Predator


I've heard of that too how great would that be if it was available on a wide scale. Like someone said before what about the danger of crashing when its made of such lightweight materials. Unless it was made of carbon fiber or something sturdy of that sort i woudn't want to have anything to do with that. I just cant see how car companies haven't slowly started applying batteries to cars to make something like the upcoming chevy volt. I know our technology now is somewhat limited, but im sure they could put in enough batteries to run a car 30 miles and then revert back to a normal gas engine. I cant remember where i heard this but i remember somewhere saying that most americans only dive 30 miles a day or something low like that. That woudn't really help the commuters, but at least its a start.

Originally posted by bgaty
reply to post by Apex Predator

 

I've heard of that too how great would that be if it was available on a wide scale. Like someone said before what about the danger of crashing when its made of such lightweight materials. Unless it was made of carbon fiber or something sturdy of that sort i woudn't want to have anything to do with that. I just cant see how car companies haven't slowly started applying batteries to cars to make something like the upcoming chevy volt. I know our technology now is somewhat limited, but im sure they could put in enough batteries to run a car 30 miles and then revert back to a normal gas engine. I cant remember where i heard this but i remember somewhere saying that most americans only dive 30 miles a day or something low like that. That woudn't really help the commuters, but at least its a start.

It's because as far as they know, the average consumer doesn't think that the extra 1000-2000+ dollars and consequent reduction in the car's performance under IC power due to the extra weight of the system is worth that capability.

It works out with hybrid cars, which already have batteries and specialized gearboxes with dedicated electric motor/generators, though people usually have to convert regular hybrid cars through a fairly simple DIY process. But to use a typical IC powered car like that would require a powerful electric motor and a power train that incorporates it. That's not exactly a standard feature.

reply to post by bgaty


In the videos of the aircar, it says the frames (and engine) are made of aluminum (or aluminium for my Briton and Aussie cousins) because of the weight factor. I guess it would be ok if everyone drove aircars because aluminum vs aluminum is better than aluminum vs cold hard steel. And as another poster stated, looking at the prototypes I don't think an aircar is for me at this moment, lots of glass and plastic. But, I think the tech has potential. Add some sort of alternator to charge a battery cell for an electric engine and then in turn have the electric engine run a compressor to "refill" the air tanks and you'd never have to pay for a fill up again. Of course I know the technology at this point in time is incapable (as far as I know) of doing that efficiently. But if you combine different technologies you might have something here. Air power and what? maybe a solar panel to charge the fuel cell, then the electric engine and the solar panel runs a compressor? I'm sure right now you would have to still replace the tanks with freshly filled ones but it sure would make a dent in the amount of time between refills. What do you guys think?

Originally posted by Apex Predator
reply to post by bgaty

 

In the videos of the aircar, it says the frames (and engine) are made of aluminum (or aluminium for my Briton and Aussie cousins) because of the weight factor. I guess it would be ok if everyone drove aircars because aluminum vs aluminum is better than aluminum vs cold hard steel. And as another poster stated, looking at the prototypes I don't think an aircar is for me at this moment, lots of glass and plastic. But, I think the tech has potential. Add some sort of alternator to charge a battery cell for an electric engine and then in turn have the electric engine run a compressor to "refill" the air tanks and you'd never have to pay for a fill up again. Of course I know the technology at this point in time is incapable (as far as I know) of doing that efficiently. But if you combine different technologies you might have something here. Air power and what? maybe a solar panel to charge the fuel cell, then the electric engine and the solar panel runs a compressor? I'm sure right now you would have to still replace the tanks with freshly filled ones but it sure would make a dent in the amount of time between refills. What do you guys think?

The problem is the inefficiency of compressed air. When you compress gas, it heats up, and when you decompress it, it cools down. In an adiabatic process, where no heat enters or leaves the system, that's reasonably efficient. But in a situation like an air car, the energy that goes into heat is lost because you don't immediately use compressed gas. There is time for heat to escape the air tank. when you decompress the gas, it's colder than room temperature, and therefore has less volume than it did when you put it in. Energy was lost in the form of heat, so your efficiency is greatly limited.

Electric motors and batteries are much more efficient than a pneumatic system, but pneumatics are cheaper and can last longer than batteries before being replaced.

There's no point in putting in second, electric hybrid system though, because just like an electric motor can be used as a generator for regenerative breaking, a pneumatic motor can be used as a pump for regenerative braking. It's inefficient, but that's probably made up for by the fact that it's very light.

Using an alternator to charge a battery to run a motor to drive a pump to refill the air tank is a HORRIBLE idea. Think about it. The pump compresses gas, which is inefficient. It runs on electricity, at about 90% efficiency. The electricity comes from a battery which charges at about 80% efficiency. The battery gets its power from an alternator, which has about 80-90% efficiency. The alternator draws ALL IT'S POWER FROM YOUR DRIVETRAIN, which means that you'd get way better power and driving range between refills by leaving that whole system out in the first place.

Ie, every unit of energy you get back into your air tank takes two or three from what you started with. You may as well drive with your brakes on all the time for the good it'll do you.

I'd like an air car just because I like mechanical systems better than electrical systems. (and I'm an electrical engineer! I'm weird!)

Nissan plans electric car in U.S. and Japan by 2010

New consumers in heavy populated developing countries where demand is expected lead, should have no problem supporting an 'affordable' electric car revolution. The average American consumer, with our established appetite for size, speed, and trendy design...may still require a bit of a re-education. In the new economic paradigm, $5 petrol may prove to be quite an effective teacher.

This has the earmarks of being a serious commercial move by Nissan