The Electric Wombat. Story and photos by Joe Greeves. December 2006 edition of Kit Car Builder: www.kitcarclub.com Click on a photo for an enlargement.

Andrew Schler is a computer engineer working for General Electric in Melbourne, Florida. In addition to being a conservationist and concerned about the environment, he also wanted to reduce his fuel bill, (and that was back when it was less than two dollars a gallon). Although it was only a 25-mile commute to his office, his full-size Ford pickup burned quite a bit of gas and he knew there had to be a better way. An expert in energy management systems, Andrew began investigating electric-powered vehicles.

Thanks to his father's mentoring, Andrew was particularly well suited for the task. He tells the story of rebuilding his first Volkswagen engine at the tender age of eight. He wanted to make sure he knew exactly how everything worked by the time he was 15 so he could get his license! Although he's owned half a dozen different cars in the past 20 years, it is interesting that he's come full circle with a VW.

Like most one-of-a-kind projects, this one began with a pencil, paper, and lots of research. Andrew had to source the rolling chassis, the electrical powerplant, and a body to join the two. He chose Electro Automotive, a company that has been providing automotive electric conversions since 1979. They offer a package that includes the electric motor, speed controller, circuit breakers, fusible links, gauges, charger and more, plus an adapter to connect the electric motor to the Volkswagen transaxle. Motor choices come in three varieties; 96 volts, 120 volts, and 144 volts. Choosing the middle ground, Andrew calculated that the 120-volt motor (about 80 horsepower) would be enough to propel the car and the weight of the batteries. The 120-volt motor required twenty six-volt batteries as a power source.

The next step was finding the running gear and the body. The Hummbug (since renamed Wombat) appeared to be the perfect choice with its full-length VW floorpan, steel subframe, Coremat-reinforced fiberglass body, and enough interior space to house the bulky collection of batteries. The front storage compartment, area behind the driver and passenger seat, and the rear compartment where the engine used to reside, could all be pressed into service.

Andrew purchased a $200 Bug rolling chassis from a salvage yard and began the reconditioning process. A new VW front end and a set of four coilovers, from the JC Whitney catalog, was the first step. The original front drum brakes were replaced with discs and the stock 22mm rear torsion bars gave way to off-road, 30mm versions. Andrew retained the VW transmission but uses only first and second gear. After bolting the electric motor to the transaxle, Andrew fabricated the component mounts along with a sliding rack mechanism that holds the five rear-mounted batteries. Next he created racks and boxes for the ten batteries inside as well as the final five batteries located in the forward storage compartment. All were wired in series to produce the necessary 120 volts. The VW gas pedal was connected to a potentiometer that controls engine speed by varying the voltage. Starting off in first, he shifts to second at about 20 mph, continuing on up to a top speed of about 65.

Since the car was designed as a commuter, Andrew rarely exceeds 45 mph during the 25-mile round trip between work and home. He estimates the range on a full charge to be about 45 to 50 miles. The Russco Engineering battery charger, behind the passenger seat, senses the level of charge in the battery pack and tapers the charging current accordingly. Plugging in at night brings the batteries up to full power but uses such a small amount of electricity that it is hardly noticeable on the family electric bill.

Although there are few frills to the car, the Wombat is equipped with headlights, taillights, side reflectors, wipers, and everything else necessary to be street legal. The stereo inside is a Panasonic CD player with Jensen speakers in the kick panels and Panasonics behind the seats. Jeep seats (also from Whitney) provide a comfortable ride and the side curtain doors have clear plastic windows that unzip for fresh air. The convertible top can also be removed for highway sun-tanning excursions. A separate 12-volt system runs the lights, turn signals, horn, and radio, drawing its charge from a DC-to-DC converter connected to the 120-volt main battery pack.

Gauges on the dash include a speedometer along with a 0-150-volt meter that, like a gas gauge, measures the voltage in the main 120-volt traction pack. When it starts dropping, you know you'd better plug in soon. The second gauge measures motor amperage and the objective is to run at high-voltage and low amps to maximize range. The unit is sensitive enough to detect head winds and tail winds. The final gauge monitors the separate 12-volt system. Everything else is quite straightforward with the exception that when under way, there is virtually no noise except for a little drivetrain rumble and the sound of wind rushing past.

Painted a Pewter Metallic to add an aggressive look, the Wombat sports a scaled-down brush guard and rear luggage rack as part of the kit. The heavy-duty spare tire rack continues the offroad theme, as do the large 15" wheels (JC Whitney) wrapped in Michelin X-series radial tires (235/75-R15), specially designed to minimize rolling resistance. Future plans include the investigation of a smoother, more aerodynamic body. Since both the original Hummer and the smaller Wombat have all the aerodynamic subtleties of a brick, Andrew feels that higher speeds and longer range could be achieved with something that presented a lower coefficient of drag.

How is the car to live with? The reception is always positive with guys thinking the car is 'cool' and gals thinking it's 'cute.' Both genders are impressed with the electric powertrain. How is it on the road? Andrew learned early about the concept of "growing gas," having run out of power several miles from home. Optimal driving techniques stretch the range of the vehicle but most of us are out of practice when it comes to driving economically. The story has a happy ending since in just a few minutes the batteries recovered enough so that he could resume his trip home. He has been driving the car for three years and there have been no maintenance requirements other than occasionally adding water to the batteries. He estimates they will need to be replaced approximately every five years.

Electro Automotive
Dept. KCB
PO Box 1113-W
Felton, CA 95018-1113
831/429-1989
www.electroauto.com