I am NOT a fan of so-called Hybrid cars, as I see the potential
advantages to be minimal, far smaller than the public is generally
told. Everyone seems to overlook a basic Law of science called the
Conservation of Energy. Hybrid vehicles are presented as though
they CREATE new energy to become more efficient! No one seems to
notice that GASOLINE has to be burned to run the same gasoline engine,
but now to turn electrical alternators to make electricity which is
then stored in batteries and then later used to run electric motors
to drive the vehicle. The simple fact that the SAME gasoline has
to be burned in the SAME engine, pretty much eliminates any MAGICAL
accomplishments! In fact, each of the steps required for the hybrid
process has its own efficiency issues! So once the gasoline engine
has applied its 21% overall efficiency in converting the energy in
the gasoline into being rotary power, instead of using a transmission
and drivetrain to turn the vehicle's wheels, many additional
processes are necessary. Each additional process reduces the overall
efficiency even more, and NONE can magically INCREASE that overall
However, there is a concept that I gradually came up with that is technically a Hybrid vehicle. The generic 1985 V-6 Oldsmobile that I had started modifying was to keep the good gas mileage of its moderate-sized (3.0 liter) engine, and would have still LOOKED like the original car, but it was intended to be able to accelerate at a rate that dragsters would be proud of, using around 840 horsepower for extremely impressive hole-shots at traffic lights!
I would be willing to help Detroit or Toyota or someone else to build this practical vehicle and probably economically priced vehicle, which has some vague similarities to some parts of the Tesla electric sports car!
Long ago, I realized that NO driver ever actually USES the huge horsepower of the over-powered cars that are sold, EXCEPT for a maximum of less than 30 seconds at a time. In all the time I have owned my Corvettes, and an Austin-Healey 3000 and other sports cars, there has NEVER been any time where I had my foot to the floor for more than 15 seconds, and that was during a quarter-mile drag where the vehicle went from zero to around 120 mph in around 13 seconds. So it occurred to me that it really is foolish for people to buy cars that have giant engines that are advertised as 470 horsepower or 505 horsepower! At all times other than those few seconds, the driver has to be paying for gasoline that is being burned for the CAPABILITY of that power and acceleration.
In an entire year of owning and driving a Corvette, I doubt that there are more than a twenty times when I really use massive power for more than maybe three seconds at a time. I realized that meant that I actually USED all the power that Corvettes are known for, for maybe ONE MINUTE TOTAL per year!
During the Summer of 1992, I had started assembling an experimental vehicle, based on a 1985 Oldsmobile Cutlass Ciera 3.0 liter V6 front-wheel drive car I then had. (It was later vandalized beyond possible repair, so I have not yet again pursued the project with any other car [yet]). The car was mid-sized, capable of holding five or six people, a pretty standard vehicle. Its moderate-sized engine permitted tolerable acceleration but never anything really interesting (to a Corvette owner!)
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I also knew that even a STANDARD car battery can contain around 80 ampere-hours of electric power in it, which, at 12 volts, is about 1 kWh (80 * 12 Wh, as discussed above). That meant that the one standard battery could provide about 1.5 horsepower for an hour, but that also meant that it contained enough power to provide 1.5 * 60 or 90 horsepower for one minute, or 180 horsepower for 30 seconds, or 360 horsepower for 15 seconds! (A deep-discharge battery has even more energy capacity.)
So my experiment was/is to be a car like the generic Cutlass Ciera, with its standard 120 hp engine, but where EACH of the rear wheels was replaced by an electric-motor-driven wheel, driven directly from TWO(*) batteries in series. (Total, two motors, resembling car starter motors, and four standard car batteries in the trunk, a rather minimal added expense beyond the modest cost of the standard Cutlass Ciera!
Maybe it would represent adding $1,000 to the cost of NEARLY ANY front-wheel-drive car. And what would be the result?
In the process of turning the engine to start a vehicle, it can briefly draw around 500 amperes of electricity from a (single) battery. At around 10 volts, that is around 5,000 watts. Since each horsepower is equal to 746 watts, a normal starter has the capability of producing around 7 horsepower or so (ball park, each Make and Model and engine size is different, and with modern vehicles with tiny motors, they need less horsepower during starting so most MODERN starters have less capability.
Just adding 7 (times two) horsepower would not be worth the trouble. But starter motors are designed to be durable enough to reliably start the vehicle for many years. So long ago, people learned that in order to start engines that had really exotic camshafts, a standard starter and battery just didn't cut it, it didn't turn the engine fast enough to start. So what was their solution? You guessed it! They used the SAME starter motor, but ran it on 24 volts instead of 12! Two batteries in series! In Electrical Engineering, a standard formula is that the POWER is proportional to the SQUARE of the voltage, if all other variables are kept the same. Instead of the starter producing around 7 horsepower to start the exotic engine, it produces around 28 horsepower. So at dragstrips, you often hear starter motors which sound like dentist's drills because they are spinning so fast. BUT AN IMPORTANT FACT IS THAT THEY STILL LAST FOR A DECENT TIME!.
My experiment was to use that (conservative) arrangement in the Ciera, four batteries. The experiment would therefore be expected to add around 56 horsepower (28 * 2) extra to the 120 horsepower of the conventional engine. Not spectacular, but the total of 176 horsepower would actually have greater benefit than that, because the 120 horsepower RATING of the standard engine actually got far less horsepower to the wheels! So I figured that my rather economical experiment should provide GREATER THAN 50% faster acceleration, likely close to double the acceleration. Given that using 24-volts to power race car starters has long shown that the starter survives pretty well, I consider that a very conservative experiment!
Of course, the next step would be to try THREE batteries for each of the starter motors. I am not aware of anyone who has done that before, so it is not clear how long the starter could operate before becoming toast. However, the simple fact that it is NEVER intended to be powered for more than 3 to 10 seconds at a time, figures to allow the starter windings plenty of time to cool back down!
In any case, using three batteries for each starter motor should produce as much as 7 * 32 or 63 horsepower at each rear wheel, or 126 additional horsepower. I am suspecting that an innocent looking Cutless Ciera with a putt-putt engine should have impressive acceleration with 126 additional horsepower!
And of course, my sugar plum dreams would require at least TRYING four batteries for each! That would be 7 * 42 or 112 horsepower at each rear wheel, or 224 additional horsepower. Now keep in mind that these experiments would all use GENERIC STARTER MOTORS, and that the recent Tesla sports car uses a very exotic (and very expensive) motor and battery pack that has proven that even greater power could be had. Imagine if EACH of the rear wheels could provide 360 horsepower for 15 seconds, then that vehicle should have acceleration that would be beyond belief!
I intended to put an activating switch under the gas pedal, where when I would floor it, the Ciera engine might be producing its 120 hp, PLUS the horsepower from EACH rear wheel, or a total of a lot of horsepower (but for only 15 seconds max!)
Under all NORMAL driving, the Ciera would get the excellent gas mileage that its small engine could provide, and that engine could probably be even smaller, a four-cylinder instead. But for those few seconds when acceleration was desired, it could be spectacular!
Note that this vehicle was essentially ALREADY approved by the government safety testing and all the rest, so it would immediately be street-legal. The tire-grip might not permit it, but 0-60 in less than 3 seconds seems possible! FAR faster than ANY car on any road today!
And all from only maybe a $1,000 increase in the cost of the vehicle! Or the sky's the limit on cost for creative variants!
The giant vehicle manufacturers all design and build either under-powered tiny vehicles that get great gas mileage or they design and build vehicles with hyper-performing high-horsepower engines that perform great but which have lousy gas mileage. The approach I have described above is better than both, in that it combines the best of both general designs! And at a vehicle price that would not be much above their current under-powered offerings!
I guess that what I have described here is a sort of Hybrid vehicle, since the gasoline engine would drive several alternators that would recharge the batteries after a performance show. But it entirely different from what the vehicle manufacturers think is a Hybrid!
However, in my intent of modifying my Ciera, I was aware of two problems that seemed possibly hard to overcome. I knew that standard car starter motors only generate around 7 horsepower, where I wanted much more. The other problem is a result of that, in that a standard car battery is designed to have the energy drain rate of the standard starter.
I considered re-wiring a standard starter to have fewer windings of heavier wires, so that it drew a lot more current, and therefore generated more power. However, with my target of hundreds of horsepower, I was not really sure whether my modification of a starter motor would cut it! So I was quite excited when the Tesla came along and it has a single electric motor which they rate at 180 horsepower! And equally, their battery-pack is clearly capable of supplying the electricity very rapidly for such horsepower. So the Tesla apparently has the resolutions to BOTH of the issues that had concerned me! And where the Tesla needs to be able to withstand that level of energy flow continuously, all I would need would be a max of about 15 seconds worth. I suspect that would mean that less-expensive batteries might be sufficient and the motor could be designed to have an operating lifetime comparable to car starters, measured in minutes!
In any case, I believe my approach makes a lot more sense than what any of the giant vehicle manufacturers are now selling or designing, primarily since it can allow "nearly stock" vehicles, for both government safety approvals and for vehicle pricing that the public might be able to afford.
In a "don't do this at home" theme, there IS a possible safety issue. Say that one of the motors burned out or didn't start and the other one worked. Then ONE rear wheel would be producing a lot of torque and power, which seems likely to cause the vehicle to instantly go out of control. A bad deal! A related issue could be related to whip-lash injuries for occupants when all that extra power suddenly kicked in. If you have been in any high performance vehicle during a serious hole-shot, you know how you are thrown back into the seat! So this sort of concept would need a good deal of safety testing to make sure that unexpected things did not suddenly occur.
C Johnson, Theoretical Physicist, Physics Degree from Univ of Chicago