The Hybrid Electric Vehicle Michael Hackleman Copyright 1988 Michael A. Hackleman Transportation consumes 13% of America's energy budget. This relatively small figure easily disguises the difficulties we face in "cleaning up our act" in this one area. It's easy to monitor and control the emissions of one large, centralized power plant. Not so 6,000,000 tailpipes. This is a good time to take a hard look at the way we do transportation. Even a cursory glance suggests that it may be more practical to look hard at alternatives than to perpetuate the current trends. Or, as Jonathan Tennyson puts it, to design solutions rather than fight problems. Fortunately, there are good alternatives, and this article explores some of them. ^Every once in a while, I get a glimpse of the future. I'm not sure if it's the future that will be, or simply one that can be. Still, when I look at the vehicles zipping about on roads in this hypothetical future, what I see is elegant designs that are quiet-running and pollution-free. They are sleek forms that look and perform as though they are very light. Is this a flight of fancy? Hardly. The vehicle I've described is a high-performance, unlimited range, hybrid electric vehicle. And it takes no stretch of the imagination to see it, or believe that it exists, because it's here, right now. Admittedly, it's a bit scattered. Or, rather, the technology is. You've probably seen some pieces of it yourself. You may have an inkling of it if you saw the cover of Popular Science in November, 1976. Or if you've faithfully followed Tour de Sol (the solar car races in Switzerland) for the past 3 years. Or the 2200-mile, transcontinental race in Australia held in November of 1987. Or if you attended the 1st American Solar Cup (solar-electric) race held in Visalia in mid-September of this year. I am fortunate enough to have seen all of these pieces, and many more. Electric vehicles have fascinated me for years. So much so that, in 1977, I wrote a book on electric vehicles, publishing a 2nd edition in 1980 to describe the emergence of the hybrid EV. Why? You cannot talk about the power an engine produces without also talking about its speed, or RPM (revolutions per minute). Engine's produce their "rated" POWER at their "rated" RPM. For most engines, that's 6,500-8,000 RPM (to your ears, that's a roaring scream!). They do produce power at RPM lower than their rated RPM, but there's a lot less of it, and it's less efficiently generated. Engines are happiest and most fuel efficient when they maintain both a constant speed (near their rated power) AND a constant load. In a car, this condition exists ONLY at idle, or at 55 MPH on flat terrain with no head wind. At any other time, the engine is fuel INefficient, and much less powerful. FMotors have a useful voltage/power relationship. At half the rated voltage, the motor delivers half the HP -- that's 5 HP at 50, 500, and 5,000 RPM. At twice the voltage rating, a motor typically delivers twice the HP -- that's 20 HP at 50, 500, and 5,000 RPM. That's all a bit technical. The implications of these attributes can be translated this way: 1. Motors don't need transmissions. The motor works as well at 5 RPM as it does at 5,000 RPM. A two-speed transmission is handy to handle steep inclines at low speed, but it's not mandatory as it would be for an engine. aPaul Shipps, a longtime EV designer and builder, has published detailed plans for converting many types of vehicles to pure (battery-only) electric propulsion. Plans exist for the VW Beetle and Rabbit, Chevette, Datsun B-210, Pinto, Fiat 128, Honda Civic, and a few others. Paul also manufactured and sold adaptor plates for mating the stock 20-HP GE motor to the clutch housings in these vehicles. If you own or have access to one of these vehicles, this is an excellent start. If you'd rather convert a Fiero, Triumph, or other car, his book, EV Engineering GuideBook, will be a big help! His dedication, experience, and plain good sense, coupled with career work in aerospace structural design, is a solid asset. His publications puts all the relevant issues on the table, and he's got maddening detail to back it up. (See Sources and References, below.) 4. Have you designed, built, or owned an electric vehicle? Do you know of someone who has? Please let me know! I want a strong Letters from Our Readers section in the EV Networking Newsletter, and source material for feature articles. Please send photos or slides, too. Don't forget a phone number! 5. Ask what you will and say what you want, but please -- don't expect a personal reply. I find it difficult to resist doing this, but the personal toll -- time, energy, etc. -- is a major diversion, and a contributing factor in a burn-out I experienced a few years ago. I am willing to coordinate a newsletter that does widespread networking, disseminates information, and facilitates deployment of EV technology. If your letter isn't answered there, chances are you just need to make better use of the available material, finding the answers to your own questions! It's been fun writing this. I hope you enjoyed reading it. Michael Hackleman None of these issues are properties inherent in transportation itself. It's how we're doing it. While IC-engines do act like "atmospheric processors" in their current configuration in vehicles, they can play a more subjugate role in the hybrid EV . First, however, let's explore the characteristics of electric motors. Electric Propulsion & Vehicles Electric motors are well suited to transportation because of two primary attributes: their power curve and their voltage/power ratio. Motors have a flat power curve. Thus, motors deliver their rated power over their full range of RPM. Read that again. A motor rated at 10 HP (horsepower) delivers most of that at 50 RPM, and at 500 RPM, and at 5,000 RPM. All of this occurs at its "rated voltage". 2. Motors perform well if they're underpowered or overpowered. This suggests simplified control functions. That is, motor power is controlled by varying the voltage to it. It also means that motors can take some abuse. A 15HP motor will, by increasing the voltage to it, produce 2-4 times its rating (that's 30-60 HP) for short durations. It's ability to channel some hefty energy is just the ticket for occasional peak loads like heavy acceleration, climbing a steep grade, or passing another motorist. 3. Two motors, each rated at 1/2 of the total required vehicle horsepower, can be hooked individually to the wheels they power, eliminating the need for a differential assembly, and giving you a motor to come home on if one becomes inoperative. 4. A small motor replaces a big engine. This involves two parameters: HP rating and physical size. Typically, a 15-HP DC motor replaces a 100 HP engine! Remember, an engine must be built for a peak power need, and to offset inherent, low-RPM performance. An electric motor is rated for continuous performance, and has inherent characteristics that enables it to double or triple this output for short durations. Motors are physically small, too. A 15 HP motor is 1/6 the weight, and 1/20th the size of a 100-HP engine! 5. Motors in vehicles don't require clutches. A clutch is needed with engines to help shift gears in the transmission. No gears, no clutch. Again, a clutch can be useful in an electric vehicle -- as a disconnect for coasting or safety, for a smoother start, and to limit the initial inrush of current to the motor -- but it's genuinely an option. 6. Motors are simple. There's one moving part and, in normal service, only inexpensive brushes need replacement. No carburetors, timing, or valves to adjust. No fuel filters, air cleaners, spark plugs, or points to replace periodically. Engines are hard to pull out and put in, have bushels of parts that can go bad, and cost a small fortune when they do. Engines leak, too, and oil is a magnet for dirt. So, engines burn dirty, work dirty, and smell dirty. On the other hand, motors make for a clean machine. Why Aren't Electric Vehicles in Widespread Use? If they're so great, you might wonder, why aren't electric vehicles in widespread use? A good question! The best answer is: they haven't really been able to "show their stuff". Hybrid EVs, like the one I described at the beginning of this article, are very rare. A more common electric vehicle is the "conversion". Like the name implies, this is a car or van that has been modified to use electric propulsion. Typically, a 30 HP, 96-volt motor is bolted into a standard car that's had its engine pulled out (blown up, more likely, and then removed). Everything else that came with the car is still there -- transmission, differential, sometimes even the gas tank is left in place. Lead-acid batteries are added, lots of them, often filling every nook and cranny. Since there's only one energy source for the motor (the battery pack), this configuration is often referred to as the "pure electric". The end result is a heavy, cumbersome affair, slow to accelerate, limited in both range and speed. Go too fast, and the range is shortened further. Conversely, if you want maximum range, you accelerate slowly and limit your upper speed limit. When the inevitable battery recharge is needed, it takes a good 6-10 hours to accomplish. Every 18-24 months you must replace the batteries. Hope that nothing, minor or major, goes wrong with it. The local automotive service center won't know what your vehicle is, much less how to fix it. There were tens of thousands of electric vehicles on the roads at the beginning of this century. Many of them could outperform today's "conversions". Why? If you're building an electric vehicle, you "think" light. and slick. If you're building a car for a powerful engine fueled by super-enriched oil (gasoline), weight and aerodynamics are not issues. Today's manufacturers have discovered the merit of putting engines in lightweight, aerodynamic bodies. The formula doesn't work in reverse. Putting a low-power propulsion system in a heavy, non-aerodynamic body is "silly". The loss of engine weight is trivial compared with the tons of batteries you must add to power such a heavy brick . Understandably, the motor is always starved of power. It's penalized in each acceleration with a reduction in range. It's also easy to damage or destroy the complex electronics needed to control the high electrical loads. JThis is not my idea of an electric vehicle. I expect performance from a car -- modest acceleration, freeway speeds, unlimited range. You won't find it in the conversion. In all fairness, even in a lightweight and aerodynamic "environment", the electric motor is still somewhat restricted in performance (without investing in expensive batteries). The range is further, but it's still limited, compared with today's vehicles. Fortunately, BOTH the "conversion" and the "prototype" electric vehicles take a solid leap forward in performance AND range when configured as a "hybrid". 8 The Hybrid EV The hybrid EV combines the best features of motors with the best features of engines. The motor contributes its flat HP/RPM and variable-load characteristics, short-term high-power endurance, and its light weight. The engine contributes its high-power density and fuel availability. In the process, each offsets the disadvantages inherent in the other. The specific configuration is important. The OCU (or Onboard Charger Unit) is a small engine (i.e., 8 HP) coupled directly to an alternator. The alternator's output is connected to the batteries. The powered wheels are connected (through a single gear ratio) to the motor(s). Motor power is supplied through a controller, the input of which is tied to the batteries. Note that the engine is NOT coupled to the drivetrain mechanically. THere's how it works. Going shopping? You zip down to the store a few miles away on battery power alone, using energy you stored from utility power, a solar array, or your small hydropower setup. After a few stops, you head home, and plug the vehicle into its charging station. A bit later, you get a call from a stranded spouse. More distance is involved, so you light off the OCU. It hums along producing steady, consistent power. When you're stopped at the light or stop sign, all of the OCU's power is going into the batteries. When you're traveling down the road at 15 MPH, some of the OCU's power goes to the motors, and the remainder goes into the battery pack. At some speed, say 35 MPH, all of the OCU's output goes into the motors. At 50 MPH, the batteries supply the additional power (above the OCU's output) needed to reach and hold that speed. More generally, in this vehicle, anytime you go below 35 MPH, OCU power is diverted into the batteries. Anytime you go above 35 MPH, the batteries supply the difference. If you stop the OCU, the batteries take up the full propulsive load. 'Here are a few relevant observations: 1. Wheel RPM (and vehicle speed) functions independently of the OCU engine's RPM. The electric motor keeps pace with the wheel RPM. 2. Each electricity source -- batteries and OCU -- operates independently of the other. You can drive on battery power alone, or the OCU alone (at some modest speed, like 35 MPH). Like any good partnership, both the batteries and OCU work together well, or independently of each other. 3. The engine is relieved of the task of producing PROPULSION and assigned the task of producing POWER toward the propulsive effort, battery storage, or both. Thus, when the OCU is operational, the power it produces is never wasted. It's used or stored. Compare that to an IC-engined car stuck in a traffic jam or waiting for a signal light! 4. The OCU gives the hybrid EV "unlimited range". As long as you add fuel, you can operate the vehicle. When higher speeds are used, the battery pack will eventually be depleted. At this point, you may continue at a reduced rate of speed (equal to OCU output alone) or stop for a while, enabling the OCU's output to recharge the battery pack before continuing on at a higher rate of speed. 5. The OCU's engine should have a long service life. Constant load/speed operation of an engine promotes equal wearing of parts, ensuring the greatest engine longevity for the number of hours it's operated. 6. The OCU's engine is less complex than the one used in an IC-engined car. The OCU's engine is smaller, uses a simpler carburetor (a wonderful byproduct of the constant load/speed setup), and has fewer parts. There's less to adjust and go wrong, less expensive parts, and minimal labor for repair or overhaul. There's a lot less heat to deal with, too. 7. Operation in colder climes is made both feasible and comfortable. The OCU's air-cooled engine cannot freeze and crack. With some forethought, the heat it does generate can be routed to provide compartment heating (a real problem with pure EVs). As well, an early lightoff of the OCU in cold weather will warm the battery pack (charging full batteries produces heat), ensuring their optimum performance in operation (a must for lead-acid batteries). 8. An OCU-configured engine is less polluting. Since it is so small and operates efficiently all the time, the OCU engine needs minimal or no pollution-control devices. Furthermore, since pollution-control devices actually contribute to an engine's inefficiency, their absence further reduces exhaust pollutants. 9. More "miles per gallon" has an interesting converse: "less gallons per mile". By decreasing the amount of fuel needed to go the same distance, the hybrid EV design makes it immediately cost-effective to use alternative fuels -- i.e., alcohol, hydrogen, etc. This aligns itself better with the output one might expect in a small-scale alcohol production facility centered on a small farm or in small communities. 10. A hybrid EV makes lead-acid batteries a feasible choice for the battery pack. Lead-acid batteries have low power density and low efficiency compared with other battery types. However, they're inexpensive, readily available, and have a recycled industry behind them. The hybrid configuration offsets inherent lead-acid battery deficiencies in several ways: a. It minimizes the NUMBER and DEPTH of charge/discharge cycles the batteries must endure. This increases battery longevity, permits the use of batteries that cannot survive deep discharge, and limits the exposure of the battery to the effects of sulfation. b. It relieves the battery of the need to store a large amount of power at one sitting, and to ladle it out over the range of the vehicle in operation. The OCU should handle the brunt of the propulsive effort, while the batteries dish out or absorb energy as needed. In this configuration, then, the battery pack acts more as an "accumulator" than as a power source. 11. The OCU doubles as a mobile power source -- for use at or away from the homesite. For a small cabin or homesite, it can BE your power source. Or the OCU can charge your cabin's battery pack. Owning a Hybrid Electric Vehicle There's four ways to own a hybrid EV, like the one this article describes: buy one, convert an IC-engined vehicle, convert an electric vehicle, or prototype your one yourself. Buying a hybrid EV Where can you get a high-performance, unlimited range hybrid electric vehicle? I can't tell you. I know of no current source for one. Jonathan Tennyson's group (based on the big island of Hawaii) is working on a production commuter prototype that uses solar-generated electricity instead of an OCU. James Worden, the main person behind the MIT solar-electric car (and winner of the solar-car race in Visalia this past September), plans to do the same thing. My own design (battery, OCU, solar, and regenerative braking) is in a prototyping stage. All of us figure on limited production in 2-3 years, and full production in 5-6 years. My own scheme involves plans and kits for DIY'ers (Do-It-Yourself) following the prototype stage. 0No doubt, there's lots of folks out there, puttering away in old garages, fittin' this to that, working out similar schemes. Some folks, of course, keep matters like this a big secret, and you never hear a word until they're ready. Convert an IC-engined Vehicle You have the option of converting an existing IC-engined vehicle to electric propulsion, hybrid-configured or not. If you're sharp, good with your mind and hands, familiar with tools, have the shop and space, the time and patience, the money and fortitude, savvy about mechanics and electrics, you can do it. If you're shy on any of these, maybe you know someone who can fill in the missing pieces. Or do it all for you. Any vehicle you convert is already compromised in the areas of weight and aerodynamics, so start light and sleek. } Convert an Electric Vehicle There are many electric vehicles on the road today -- disguised as regular cars -- that will readily adapt to the hybrid configuration. These falls into two classes: industry-converted or home-converted. The EAA (Electric Auto Association; see Sources and References, below) is comprised of people who own, are building, have built, or dream of building their own EVs, and this is a good source of information, components (motors, controllers, etc.), and electric vehicles. Look for a chapter in your area, suscribe to their newsletter, find out when they're meeting (or rallying) in your area, and treat yourself. You'll see both homebuilt and industry-converted vehicles. Go for a ride, mingle with the crowd, learn the language, try not to salivate too much. This experience can turn you On or turn you Off, depending on your expectations. Modification of an electric vehicle to the hybrid configuration requires a careful analysis of what is possible, what you want, and what exists -- and how to bring the this trilogy to fruition. A clue: Basically, you're adding a standby generator, removing 1/3 to 1/2 of the vehicle's existing battery pack, and making some tough choices about the motor control system. See Sources and References, below. Prototype your own Hybrid EV Prototyping your own is a devilish temptation. Why? The propulsive requirements of a high-performance, lightweight, aerodynamic hybrid EV are absurdly LOW. We're talking about 2 to 4 HP for the drivetrain, a 3000-watt engine-generator, and a 72-volt, 100 AH battery pack! Of course, you must build an elegant environment for such a small powerplant, and that's not easy. If you want to succeed AND survive the experience, you must be real hungry. And possess: 1. The ability to define the relationship between any two of the following factors: performance, aesthetics, safety, acceleration, speed, hill climbing ability, range, environmentally-benign technologies, recycling, maneuverability, crashworthiness, aerodynamics, lightweightedness, cost/benefit ratios, and prototype development standards. A2. Knowledge of what sub-assemblies are lightweight or otherwise useful to your vehicle, i.e., Pinto or Baha Buggy steering/brake/suspension systems; shaft-driven, motorcycle rear ends; aircraft generators for propulsive motors; etc. 3. A smattering of knowledge about batteries, motors, control systems, engines, generators, alternators, steering, suspension, brake systems, fiberglass construction, electricity, and electronics. 4. Demonstrated skills in drafting, design, fiberglassing, survival, diaper-changing, massage, reflexology, and singing before hostile crowds. It helps to feel okay about being a half bubble shy of level, and having lots of friends that fit that description. If you don't have disposable income and a dedicated space, you get creative. What's creative? A strong ability to mesmerize curious skeptics and convert them into workers willing to perform menial, dirty tasks for long hours at no pay while retaining the feeling of how lucky they are to be working with you. The Huckleberry touch. Note: I am finishing a 2nd article that addresses issues of prototyping your own in extensive detail. If prototyping intrigues you, there's more on this topic in the next issue! Last Thoughts ^The hybrid electric propulsive system is new to vehicles, but it's not a new concept. Actually, it was successfully demonstrated during World War II in the American submarine! Testament to its success there is the current use of hybrid technology (without the batteries) in the diesel-electric locomotive, the mainstay of our railroad system. In essence, this says that the technology is, indeed, really here. If you found all of this interesting, but you really need to go wash those dishes, hey, I appreciate the time you took. If you find yourself a bit hungry for more, here's some possibilities: $1. Start reading. Electric Vehicles: Design and Build Your Own appears to be the only book in print on EVs. It has been out for a long time, so it's likely to be in your library. Check it out and read it. If the cover doesn't say Second Edition, you need to order the EV Supplement ($3) from Earthmind (address below); this will supply the chapter that was added to the 2nd edition. If you want your own copy of this book, send $10 to Earthmind, P.O. Box 743, Mariposa, CA 95338. 2. Order EV Sources & References. This publication lists: ^a. every book I have in my EV library, and describes what they cover. Most of these pubs are out of print. However, I will indicate their availability. (Note: This publication will be completed by the time you see this article in print. Currently, I am tracking down the publishers/authors of these books, discussing reprinting issues, and obtaining reprinting/publishing rights, if applicable.) At least, it'll give you some titles to run through your local library's computer. At most, I'll loan you a xerox copy of any of them. Inquire about this; you'll need to supply a deposit and pay 2-way postage. b. catalogs, companies, and other sources for EV-related components, new and used. This will be updated continuously through the EV Networking Newsletter (below). EV Sources & References is $3; see Mailing List, below, for ordering address. 3. Get on my mailing list. Send a SASE (self-addressed, stamped envelope) or send postage money to: Michael Hackleman, POB 1161, Mariposa, CA 95338. Why? Several projects are in progress; among them: a. An EV Networking Newsletter. b. A documentary video on EVs (featuring the Solar Cup race). c. A lending library for EV videos (Tour de Sol, National Geographics coverage of the Australian race, Solar Cup 88, etc). As these firm up, I'll have a way of letting you know -- IF I have your address! (Sorry the file is a little munged...came out of the text converter that way though...DCK)