Why Lighter is Better In Electric Car Conversions
Reprinted with author's permission from Seattle Post-Intelligencer.
My previous post about an up-coming electric car conversion class here in Seattle got a lot of interest. I have been asked several questions; the main one being "can I convert my car?"
Well, here is an answer and some basic information.
I'm no expert on converting gasoline cars to electric, but it's my understanding that if you are going to do a conversion, you are better off using a light-weight vehicle instead of a heavy one. Now, what do I mean by light or heavy vehicle?
Think of compact and subcompact models as light-weight vehicles. Used cars like the Geo Metro, Honda Civic CRX, and VW Rabbit (all of which are no longer produced) are compact vehicles that are great for converting to electric because they each weigh less than 2,000 pounds.
Heavier cars such as the Toyota Camry, all Subaru models, and any other mid-size sedan are not ideal for a conversion. The 2008 Honda Accord, for example, weighs about 3,200 pounds. Subaru models not only are not compact, but are heavier by design because they carry the extra parts necessary for the All-Wheel-Drive system they all feature. The AWD parts weigh about 300 pounds. That is largely why Subaru models have a fairly low gas mileage. I owned a 1996 Subaru Legacy that would get an average of 19 MPG. I also owned a 2001 Impreza, and the gas mileage was better but not by much. I also owned an Acura Integra, which weighed only about 2,600 pounds. The gas mileage I got with the Integra was about 28 MPG. The conclusion here is simple: lighter vehicles require less fuel to move, generally speaking, so they are better for converting to electric.
To find out how much your vehicle weighs, I recommend going to the MSN Autos web site.
If you are thinking of converting a car to electric, a knowlegeable person who has done a conversion can help you choose a good car to convert. If you come to a SEVA meeting you will meet lots of people who can answer questions, and you will even be able to see lots of cars that were converted and have been running on electricity! These cars don't have an engine - they have an electric motor and a battery pack. By the way, if you convert a car at the present moment you can enjoy the benefit of being able to sell the engine for a decent price, and use the money to help pay for the conversion.
For now, just keep in mind that a small car is your best choice for converting to electric. Why?
Because it takes energy to move a car (or any other object), and the heavier the electric car the more batteries that will be necessary to move it. If you have a very heavy car, then you will have to load it with lots of batteries. And batteries add their own weight to the car. Batteries are much heavier than gasoline because nothing beats the high energy-density of gasoline (only nuclear power does). To use a drastic example for illustration: if you have a semi-truck and load it with lead-acid batteries in order to move the enormous amount of mass of the truck, by the time you load it with batteries the semi-truck will be so heavy that you probably won't be able to move it. If you do move it, rest assured your batteries will discharge very quickly.
This is a very interesting topic to me because it gets me thinking about how much energy is required to move mass. Almost all of us take the astounding amount of energy contained in gasoline for granted. With gasoline you can fill an airplane tank and fly it to another continent - that is how potent gasoline is (and yes, I'm aware that airplanes use a special kind of jet fuel and not the same gasoline we find at gas stations). You cannot load an airplane with batteries and fly it to another continent. There are experiments being done and electric airplanes do exist, but we go back to the same approach we use for cars: these planes have to be very light-weight.
Have you ever thought about how much energy is contained in gasoline and what it takes to move your car?
Did you know that about 75% of the energy contained in gasoline is wasted in the form of heat because the Internal Combustion Engine is very inneficient at extracting the energy contained in gasoline, which gets transferred to the wheels of a car. So your car is only using about 25% to 30% of all the energy that is in your gas tank, and it still allows you to drive at fast speeds and for a range of 300 miles or more... that gives you an idea how [b]much[/b] energy is in gasoline!
Do you realize that (generally speaking) about 95% of the energy in your gas tank is used to move the car itself and not you the driver? The car is one of the most inneficient ways to transport people - especially when there's only one person in the car.
Oil is a finite resource and one day we will no longer have oil or gasoline. This is an undisputable fact. And this day may come sooner than later now that Tata Motors is going to be producing the Tata Nano, a car that will cost about $2,500 in India, and China has plans to sell gasoline cars cheaper than anyone else.
When there's no more oil left, or a gallon of gasoline costs $20 or $50, then people around the world will have to find new ways to commute. It just may be that we will have to rely on mass-transportation systems and redesign our cities, and even electric cars won't do (the manufacturing of cars and auto parts also requires oil). Whatever the alternative may be, the time to switch is now while we still have the resources to build what we will need.
Some day we will look back in disbelief that we burned the most valuable natural resource through Internal Combustion Engines so individuals could have the luxury of driving everywhere they wanted to go. I think electric cars are the best alternative, at least as a transition to mass transportation because electricity can be generated through renewable energy sources.
I hope that more and more people choose to convert gasoline cars to electric so they can use electricity instead of gasoline, at least until there's a wide variety of new EVs to choose from. Notice that the new EVs that are coming out are also light-weight by design due to the issue mentioned above. The Tesla Roadster is extremely light-weight (about 1,600 pounds) and the battery pack alone weighs about 900 pounds. So the battery pack (or Energy Storage System, as Tesla likes to call it) on the Tesla Roadster weigh over 1/3 of the total weight of the car! And these are some of the most advanced batteries on the market - propriatery technology developed by Tesla Motors.
BTW, Martin Eberhard, one of the Tesla founders, recently installed solar panels in his home and will soon be receiving a new Tesla Roadster. So he'll be spending no money on fuel to drive his Tesla Roadster, and will have significantly reduced his environmental footprint this way. You can read more about it in Martin's blog.
I'd like to mention that clogged roads and freeways have become a problem in cities worldwide. The new EV revolution likely will have people driving smaller cars at first - at least until battery technology improves to a point where we get higher energy-density batteries - more energy and smaller sizes. But smaller cars are a good thing for society. Not only do EVs have ZERO tailpipe emissions (they do not even have a tailpipe), but if everyone is driving smaller cars, we can fit more cars on our currently busy roads and freeways, thus reducing traffic jams.
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