The
idea of a hybrid-electric car naturally evolves from
the basic attractiveness of the electric car
itself, which, unfortunately, is limited by a shortfall in battery technology. Town Car is
based on a VW Beetle chassis, which has been switched to electric power and fitted with an
on-board generator powered by a 3 kW, single-cylinder, industrial engine. A 72 volt, 6 kW
Baldor dc motor mounts directly to the VW transaxle using an adaptor plate. All gears,
including reverse, are operable.
The motor is controlled by an off-the-shelf 600 amp
chopper controller. In order to leave room for passengers at the center of the platform,
most of the car's 12, 6-volt lead/acid batteries are located at the ends - six in front,
four in the rear, and two between the rear passengers. The body is made of FRP/urethane
foam composite. For more information on body construction techniques, click on
One-Off Construction Using FRP/Urethane Foam Composite.
Town Car's platform offers opportunities for upgrading, depending upon the user's needs
and the level of sophistication one is willing to build into the vehicle. To evaluate the
options, it helps to first understand the conceptual underpinnings of a hybrid vehicle.
Initially, the hybrid was envisioned as essentially a battery-electric vehicle with an
on-board heat-engine-powered generator (genset) to extend the range. This implied that the
genset would be of minimal output in order to bias the system toward battery-electric
power and thereby gain the efficiency of using wall-plug electricity.
Today's thinking
runs more toward a systems approach in which battery power and heat-engine power are
designed as an integral system that continuously modulates the bias between the two power
systems according to the driving schedule. The battery pack serves more as an energy
reservoir, similar to a capacitor, to account for peak demands. The genset is typically
configured for higher output, usually equaling or nearly equaling the average power
required to drive the vehicle over a particular driving schedule. This approach results in
a smaller battery pack consisting of batteries designed for maximum specific power, rather
than maximum specific energy. The result is a more energy-efficient and cleaner vehicle
(compared to conventional vehicles), and better overall performance and range (compared to
battery-electric vehicles).
As shown in the plans, Town Car's power system is configured as a battery-electric urban vehicle with range augmentation from the genset, which is the most straightforward
and simple approach. A builder could, however, change battery, motor, and genset ratings,
and install an integrated control system, and thereby change the vehicle's performance
profile. Built according to the plans, Town Car has a top speed of 55 mph, a battery-only
range of 60 miles, and a genset-assisted range of 100 miles. With the genset operating (it
is switched on manually), fuel economy at 35 mph is 100 mpg. By changing battery, motor,
and genset ratings/specifications, Town Car's maximum speed, range, and fuel consumption
characteristics can be manipulated to suite different requirements.
Town Car's system is similar to the system in the new Volt.
For more information on electric vehicles and hybrid system control strategy, see
Electric and Hybrid Vehicles: An Overview of the Benefits, Challenges, and Technologies.
Town Car was featured on the cover of Mechanix Illustrated magazine, and it was used as a background vehicle in the movie Total Recall.
Specifications |
Dimensions and Performance
Length: 176 inches
Width: 72 inches
Height: 49 inches
Front Track: 57 inches
Rear Track: 58 inches
Tire Size: ER60-14 inch radial
Brakes: Drum
Curb Weight: 2500 lbs
Ground Clearance: 6-1/2 inch
Turning Circle: 36 feet
Seating: Four
Battery Range: 60-65 miles
With Genset: 100 miles
Max. Speed: 55 mph
Cruising Speed: 45 mph
Build Time: 400 to 600 man-hours |
Propulsion System font>
Motor: Baldor 7544D, 72-V,"C" face
Rating: 8 hp @ 3400 rpm
Weight: 145 lbs
Batteries: Twelve 6 volt, 244 ah
Controller: 400 amp, 72-v chopper
Genset: Baldor Spec. No. 28B162W132
Weight: 76 lbs
Output: 2500 watts
Engine: Briggs & Stratton #111232 type 0035
Weight: 24-3/4 lbs
Output: 4 hp @ 3600 rpm |
The New Edition of the Town Car Plans Includes:
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