AC Propulsion Honda

AC Propulsion Honda

A Preview of Alan Cocconi's spectacular new EV

Winter 1994

by Tim Considine

Yes, folks, the car you see enveloped in tire smoke is an electric vehicle! Drive it gently, and it is one of the most energy-efficient, easy to drive and maintain electric cars ever made, and gentle as a lamb. Tromp on it, and hold on. From zero-to-traffic school, this car will simply blow the doors off ANY gasoline-powered four-seater, except, perhaps, for a M-Series BMW or E500 Mercedes-Benz.

Though the first actual road test has been promised to ROAD & TRACK, Alan Cocconi agreed to let ELECTRIC CAR do a preview on his latest EV. We had two sessions with the car, the first, a short one on the highways around Monterey, California, only two days after it was finished. Our second stint was closer to home, on the mountain roads of Angeles National Forest, not far from the AC Propulsion "factory" in San Dimas. In all, we spent several hours behind the wheel, enough to get a good feel for what it's like to drive this unique vehicle.

Cocconi's converted Honda CRX set the stage in 1991. It and its five successors, all Hondas but for one Saturn conversion, have served as prototypes and mobile test platforms for the most advanced high-power, high-efficiency EV powertrain one can actually buy, and perhaps, in existence. With commercially available lead-acid batteries, the old prototype is still running strong after 42,000 miles and still, until this new one is officially tested, holds most of the records for electric car performance and range. Check that, one of James Worden's converted Geo Metro commuters did exceed the CRX's range mark, but it was using a half-million dollar nickel-metal-hydride prototype battery for power.

If Cocconi's original CRX was fast and efficient, it was also rough as a cob. To allow him to test various power packs, there was (and still is) no dedicated battery compartment. To a passenger, it means sharing foot space with the batteries that wouldn't fit behind the seats. To the driver, the less than ideal weight balance means high-speed handling that feels like attempting to corner a waterbed. Not so, with Cocconi's latest offering. It is a refined and well-balanced package. In short, a real car.

Once again, Cocconi has started with a Honda, this time, a 1994 Civic hatchback CX. Only on close inspection would one see any differences between the Cocconi car and a conventional Honda.

The intake opening for radiator air has been covered at the front, panels that make, with the bottom of the long central battery box, a full bellypan, and, of course, the absence of any tail pipe are the only exterior clues that this is an electric car. Well, there's also a rear license plate frame that says, "My other car pollutes" Otherwise, it looks like a perfectly normal Honda.

Inside, however, there are major differences. A large box section runs from the firewall, between the seats, all the way back into the Honda's small luggage area. Upholstered to match the rest of the interior, this forms the sides and top of the battery pack compartment. Inside, 28 sealed no-maintenance Optima lead-acid batteries are wired together to form a pack that can be lowered as a unit (with a simple handcrank) and replaced in less than 30 minutes. Unless there's a problem, this should only be necessary once every year or two, depending on one's driving needs, as the latest Optimas are giving 20,000 miles of service.

To accommodate this wide central tunnel, the standard Honda front seats were replaced with two slightly narrower and, in our opinion, more comfortable Recaro seats. They are certainly firmer than the originals, but offer much more support. Nestled within the normal instrument clusters and an extra one atop the battery tunnel is an impressive array of unfamiliar instruments, but strangest of all is the absence of a shift lever - of any kind.

Power comes from a 150 kW (200 hp) aluminum A.C. induction motor, which is connected directly to the standard Honda transaxle, sans every gear but 1st. Cocconi has found this a simple and efficient way to, as the car guys say, put the power down. The heart and electronic brain of the drive system, Cocconi's remarkable inverter and power system, is housed in a (small) suitcase-size gold-anodized aluminum box atop the motor assembly. The whole installation is quite neatly done, obviously the work of a good mechanical as well as electrical engineer.

Needless to say, with a weight of just 3100 lb, 200 hp and 165 ft-lb. of torque adds up to some serious acceleration, as the photographs show. While we took no watches, Cocconi's estimates of zero-to-sixty mph times in the six-second bracket seem realistic to us. Unlike a gas car, electrics develop maximum torque from rest. This one just explodes off the line and if you lay into it with Cocconi's traction-control switched off, you'd better have a good credit line with Goodyear. Even with capable Goodyear Invicta GLR 165-13s, under maximum acceleration, one is traction-limited until about 40 mph.

The solution, of course, is to leave the clever electronic traction-control switched on. This has a double benefit, as it also works like an electrical equivalent to anti-lock brakes with re-gen braking. Re-generative braking is that wonderful bonus, unique to EVs,. in which the motor becomes a generator when one lifts off the throttle. The result is a braking force, up to 75 ft-lb., which is not only free, but generates a considerable amount of juice back into the battery pack. Since the majority of normal braking is taken by the front wheels anyway, this is most effective with electric cars that are front drive.

A concern, however, is the possibility of too much re-gen braking on the front wheels, particularly in a curve or most critically, when it's wet. Should that situation occur, and the front wheels locked up, steering would effectively be momentarily lost. Tires that are not rotating do not know which way they are pointed. According to Cocconi, his traction-control system is the result of just such a scary moment. Pragmatic engineering.

So what's it like to drive this technological wonder? Strange, and wonderful. It's the old story, turn the key on and nothing happens except an orange 'Neutral" button, clustered with green "Forward" and red "Reverse" buttons at the left end of the dashboard, lights up. No sound. No vibration. With foot on the brake pedal, one simply releases the emergency brake (moved to the left side, between the seat and door) and - after groping vainly for a shift lever the first time - pushes the 'Forward" button shades of the old Chrysler push-button automatics. Still, nothing happens. The familiar automatic transmission "creep" of a typical gas car is absent. In fact, it's hard to believe the thing is on until you press the "gas" pedal.

A faint, turbine-like whistle, some gear whine, and tire noise are the only things heard as one moves easily forward. We found the throttle quite linear and easy to modulate - and very responsive. Accelerating, one feels that this must certainly be the smoothest automatic transmission ever. Of course, there is no transmission. That's the beauty of a 336 volt A.C. system. And the power can be felt all the way up to respectable highway speeds. An indicated 75 mph was effortless, but even more impressive, and unexpected in an electric vehicle, was the passing power at speeds over 50.

Re-gen braking does take a little getting used to. Of course, one can eliminate it completely or select the level wanted with a slide switch to the right of the main instruments. But after just a few minutes, you start getting a feel for the braking power and almost unconsciously begin anticipating it and modulating the accelerator pedal in both directions. In our tests we climbed 2200 ft. over a 10 mile stretch of mountain road. Coming down at a rather, shall we say, brisk rate really showed the value of re-gen. Winding down one downhill switchback after another, we never once had to use the brake pedal, but rather developed a relaxed rhythm and touch for the braking action. It made us realize how much effort we waste in conventional cars, switching from pedal to pedal. Re-gen braking is so easy - and practical. Up to 30% of the total energy can be put back into the battery pack with re-gen.

We didn't have the chance to personally use it, but Cocconi has also built a cruise-control into his new inverter. Unlike conventional gas car cruise controls, which are usually limited downhill by engine braking, his system works with re-gen and will maintain a set speed, no matter how steep the grade is. You can set it for 15 mph and go down a 20% grade. The car will stay at the selected speed unless overridden by your throttle foot.

We found the handling to be quite good, given that the car, at 3100 lb, is no lightweight. In spirited driving, it turns in quite well and, despite a bit of noise from the low-rolling resistance tires, has a decent amount of grip. We turned the traction control on and re-gen off and pushed it closer to the edge of the traction envelope. Predictably, there is understeer. But like many a fine sports car, at the limit, this can be reconciled with trailing-throttle oversteer. Liftoff and the tail will gently move out, balancing the push.

No, this is certainly no Porsche, but it is a good handling four-person sedan. Right now, Cocconi says the front/rear weight balance is about 50/50, not ideal for a front drive car. If the batteries were moved about a foot forward (possible, but not without fabricating new heating and venting ducts), the extra weight over the driving wheels would undoubtedly make it handle even better.

Another clever wrinkle that Cocconi has included is the ability to control the temperature of the battery pack. Obviously, batteries do not operate efficiently if they become too cold or too hot. Aside from good insulation, fans and a built-in heater, both of which also work if needed as the pack is being charged, insure that the batteries stay within reasonable temperature limits. This is probably the only electric car that can operate efficiently in cold weather.

Charging the battery pack is a snap. Just plug one end of the supplied charging cord into the car (under the "fuel" flap, of course) and the other to a 240 or 120 outlet, set the controls inside the car, and the built-in charger takes over, automatically turning itself off when the battery is fully charged. At the fastest 240 rate, which, for the sake of battery life, is not recommended all the time, a full charge can be achieved in two hours. Or in an emergency, at that rate, one can think of the distance that can be traveled as one and a half miles per minute of charge. Normally, though, with a usable range in excess of 100 miles, the overnight charge with normal house 120 should suffice.

This being an engineer's car, and one that will probably be used by some utility, or government agency, or car maker to gain specific knowledge about electric vehicles, there is remarkably comprehensive instrumentation on-board. One cluster of instruments and controls, situated where a radio would normally be, is dedicated to the batteries. Three knobs across the top allow the driver to set the maximum current to the batteries when charging, the maximum voltage (when the charger will be shut off), and a circuit breaker rating switch, to be set just below the rating of the outlet being used to charge. That means no blown fuses or circuit breakers.

Underneath these knobs, 28 LEDs, one for each battery, perform several functions. During charging, they light up as each individual battery reaches the maximum 14 volts. At the end of charging, all are evenly lit. While running, however, if a battery gets below 11 volts, its corresponding LED lights up. That way, a weak battery can be identified immediately. And if one battery gets dangerously low, an audible beeper goes off. One edge-volt meter to the left of the cluster can be set with digital switches below it to monitor the exact voltage of any battery, or of the lowest. Two similar edge-mount meters on the right measure exact line current and voltage during charging.

There's a 24-page owner's manual that comes with each car built, a good part of which is dedicated to understanding the instrumentation. Obviously, Cocconi knows the average end-user won't want to be concerned with such details. He's already working on a small computer like those on some upscale cars today. It will display basic information, with provisions for viewing more specific data through menus. In case of problems, a beeper will sound and the pertinent information will be displayed. For now, however, there's enough data to satisfy any engineer.

In the main instrument cluster, the original speedometer remains untouched. On either side, though, there are now EV- specific gauges within the original round displays. The top half of the gauge to the left is split into analog inverter and motor temperature meters. The bottom half is an analog voltage meter for the entire battery pack. The matching gauge to the right of the speedometer is also split, with fine and coarse ammeters on the top and bottom. These give a graphic display of what is being taken out of the battery pack at any moment. Back off and they drop, much like a conventional-car computer's mpg display increases if you back off the throttle.

A third instrument cluster, on the battery tunnel, has digital displays analogous to a conventional car's gas gauge. The left two track the battery pack's total capacity and what's been put back (by regen or charging) in amp-hours, and the two on the right, the amount of amphours taken out of the battery pack put 'back, in kilowatt-hours, on a trip. Below these are a control that selects the different battery heating modes and a battery temperature gauge, and to the right, current and temperature gauges for another clever Cocconi innovation, offered as a range-increasing option with his cars, the APU or Auxiliary Power Unit.

Until batteries come on line with a range of 500 miles or better, Cocconi reasons that if electric cars are to be practical, they must have help for long trips, a hybrid option. In 1992, he built a tiny 200 lb. trailer with a 16 hp catalytic muffler-equipped Briggs & Stratton RV generator on it. At 3600 rpm, it put out 9000 watts of continuous power, enabling Cocconi's CRX prototype to run all day at 55 mph without discharging the batteries. On a 700-mile round trip to Phoenix, while the APU was running, it got 42 mpg. Cocconi has recently been experimenting with a more powerful 14,000 watt module, good for 35 mpg at 70 to 75 mph. The hybrid option has untethered Cocconi's electric car.

Instruments and controls for hybrid operation are included in the $75,000 purchase price of a Cocconi vehicle, but the hybrid module itself is another $20,000. Sound a bit strong? Well, to put these prices in perspective, imagine what a hand-built version of your favorite gas car would cost. Needless to say, with any kind of multiple production, the numbers will be more realistic.

Alan Cocconi is still on the cutting edge. His latest EV is quite an accomplishment, a real-world, practical four seat electric car that can easily be driven every day - with existing lead-acid batteries. The Impact, the Ecostar, and other high-profile electric concept cars purport to be the future. Cocconi's car is today. It's also an absolute hoot to drive.