Electronic Design

What's All This Electric Car Stuff, Anyhow?

A few weeks ago I read a letter (published in EE Times) by our old friend, Jim Hansen of New Boston, N.H. He presented several reasons why an electric car would have problems achieving great popularity, even though several states have passed laws mandating that cars that make zero pollution, must be made available, for us to buy. If an electric car is to be made efficient, it must be very light yet very strong, he observed. This typically leads to a fairly fragile structure, which is not only expensive, but, if you get into one little accident, it is liable to be bent and crumpled and not repairable. One ding and it is smashed. These will not be inexpensive cars to own, when they start having accidents.

Also, he observed, an electric car is made of exactly the kind of materials (high-current batteries, bus bars) that one would use to make a welder. In case of an accident, the arc-welding begins.... Not a fun place to be in an accident. Also, if the battery cases crack, there will be battery acid all over the street. Messy. And what if there is an electrical breakdown in the control computer? You might have a healthy motor, and healthy batteries, but you still couldn't get home. And in cold weather, how do you run the heater? In hot weather, are you supposed to do without air-conditioning?

I sat down and started writing to Jim. The problem of welding can be solved if suitable fuses are built into the bus-bar paths. The problems of acid leakage might be alleviated if suitable neoprene or rubber or plastic bags surround each battery. Not all would be cut after an accident occurs. Also, packages of alkalines or buffers could be provided, to neutralize spills. As for the computer failure, you might be able to get a limp-home mode, when the primary controller/computer poops out.

Then I pointed out to Jim, none of these reasons are enough to cause me to not buy an electric car. Heck, I only commute 44 miles in the morning, and the same at night----not a big deal. But, while the initial cost of the batteries is bad enough, the cost of replacing them every 30,000 miles is significant, since I put on that many miles every 15 months. Many promoters of electric cars ignore or gloss over the costs and problems of finite battery life. They say their operating costs are only 3 or 4 cents per mile, much better than a "typical" gas-powered car at "8 cents per mile." Well, I sure as heck do not pay 8 cents per mile to run my VW to work. Maybe 5 cents per mile, including replacing the engine every 230,000 miles, whether it needs it or not.... If I bought an electric car and it saved me 2 cents per mile, I would have to run it for 20 years to break even, not to mention, get ahead on costs. No, the cost of replacing the batteries periodically, is a significant factor in keeping me from buying an electric car.

Then I commented on the heater problem. You could easily rig a little propane heater, as an add-on accessory. That would keep your feet warm, and your windshield clear for all cold weather. BUT I have done a LOT of driving in Massachusetts. Often, I would drive to work, and the snow would begin, and by the time I wanted to go home, the highways would be 70% clogged with snow, and 80% clogged with stalled cars. You would just KNOW that you could not start out on a trip of 30 miles in conditions like that, in a battery-powered car, and have any serious hope of getting home. So, in some parts of the country, an electric car would just be trouble looking for a time and place to happen.

 Then I began to muse about some of the rule-benders that my friends knew, back in Taxachusetts. When you buy a car there, first you pay Sales Tax on it, once, and then you pay "excise tax" on it, annually, forever. If you buy a car with a built-in radio, you pay excise tax on the radio forever, too. So a number of my friends would buy a car with no radio. Then they would buy a good after-market radio, and they would be able to avoid paying excise tax on the radio, forever. Maybe such a person would buy an electric car without a radio----and without a heater. Then after he gets it registered, he could drive down to Lechmere Sales and buy an after-market radio----and an after-market heater. That way he could have a perfectly non-polluting car----but a bolt-on, modular heater. Of course, the car would have to be designed to accept a modular add-on heater, air vents and controls, too. Well, that is a neat solution to that problem. Now, does that suggest anything else?

Well, yes, it does. I think I would like to buy an all-electric, non-polluting, battery-powered car, and then drive down to Lechmere, and buy an add-on, after-market gasoline engine, or maybe a propane engine, or a diesel engine, that I could use to re-charge the batteries. This would be a bolt-on engine-generator set, so any time I wanted to remove it, I could prove that I still had a pure, non-polluting electric car. But when I wanted to go on a long trip, such as to work, I would start down the street, and as I neared the freeway, I could start the little engine, and all the way to work, I could keep feeding charge to those batteries. If I got to a traffic slow-down, the batteries would just get better and better charged. As soon as I got to work, I could just leave the engine run a few minutes, and when the batteries got charged up, the engine would shut off automatically.

Hey, now there is a rule-bender! Even better than not having to pay excise tax on your radio, and your heater, and your engine, forever, you could drive a non-polluting car, and charge up the batteries when they needed it, and not discharge the batteries very much. Better yet, you could get along with 1/2 or 1/3 or 1/4 as much batteries as usual. And best of all, the batteries would never get discharged very low because you could keep feeding them charge. So, the batteries get MUCH lighter, and the battery never gets cycled low, so, battery life would be GREATLY increased. And all I have to do is find a modular 5 HP motor-generator.... because I know that a VW can cruise at 55 mph, on the flat, with no headwind, using just about 5 HP. That's about 10 X as much power as the cute little portable motor-generator sets. So, I will have to shop around for a suitable, compact engine-generator set.

Now, while every internal-combustion engine does generate some pollution, an engine designed to run at constant speed and constant load can be designed to run much more cleanly than an engine that has to be able to run at light or heavy loads, and at slow or fast speeds. So this car, while not as clean as a car whose batteries are recharged by wind-power or hydro power, can still be a lot cleaner than most gasoline-powered cars. Still, now there is no technical reason I cannot use a "battery-powered" car. Of course, the concept of this "hybrid" car has been around for many years----but, the modular approach seems to bring some new advantages.

Then my brain began to race----maybe I can patent this? I phoned my friend Al, in the Intellectual Property group. I asked him to run a search on this concept----a modular, removable engine to go in an electric car. Wow! I could be a hero!! I could be RICH!!!

The next morning, Al showed me a 1993 patent, U.S. patent number 5,225,744, for an electric car with a modular, bolt-in engine, by a couple of Japanese engineers. Well, I had a good idea, but these guys only beat me to it by 3 or 4 years. Sigh. Still, it is a good idea, even if I have to pay royalties to these Japanese guys. They deserve it. So, one of these days, a battery-powered car may indeed be really practical. Even if the snow slows you down, the little engine can keep the battery charged. You would be able to get home----without running your batteries down. Worst case, you could stop for coffee, and leave your motor-generator running.

Finally, I threw in one more idea to tickle Jim's fancy. There are some new flywheel modules made by Flywheel Systems, (Seattle, Wash.) that weigh 40 lb, and spin a carbon-fiber rotor up to over 100,000 rpm. When you put 20 of these magnetically-coupled flywheel modules in your car, you'll have enough energy to drive as far as 390 miles. (Estimated, best case.) Admittedly, these flywheels are just in the prototype stage, but they really do have a lot of advantages over batteries. They can be "recharged" many, many times, and you can draw a lot of power out of them without straining their longevity. They are easy to arrange to be modular in parallel, so if one or two quit, you have 19 or 18 to keep you going. Maybe if I combined those with a little 5 HP engine, I would need only 2 or 3 flywheel modules...??? Maybe if I wait just a little longer, I can get all these advantages, without having to design and build the car myself...  So, Jim, it sure sounds like fun, in the not-too-distant future.

All for now. / Comments invited!  RAP / Robert A. Pease / Engineer

Address:

Mail Stop D2597A

National Semiconductor

P.O. Box 58090

Santa Clara, CA 95052-8090

1. U. S. Patent 5,225,744: Masami Ishikawa and Yukihiro Minezawa; assigned to Aisin Aw Co., Ltd., Japan. Filed April 27, 1991; issued July 6, 1993.

 

Hide comments

Comments

  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Publish