Trade Secrets

Motor, Nov 2007 by Cerullo, Bob

There's very little that's really new in the world. Almost everything has been done before, if perhaps not quite as well. The resurgence in electric vehicle development is a perfect example.

I have been intrigued by electric vehicles for as long as I can remember. The Pilgrim Laundry Company in Brooklyn, NY, where my shop was located, used to run a fleet of electric trucks. I remember them being so quiet as they rolled up to die door to deliver my father's starched white shirts. They weren't as exciting as thè horsedrawn Borden's milk wagon that also used to pull up to deliver milk, but I marveled at the quietness of die electric laundry trucks and the old Baker Electric that a longtime customer drove to my dad's shop a few times each year.

For a while there, when GM's EVl electric vehicle was undergoing consumer testing I thought electrics would make a comeback. As I mentioned in my August column, I was disappointed when GM made a business decision to end the EVl program. But good ol' Yankee ingenuity has continued electric vehicle development. In Conneflsville, PA, one of the working police cruisers is an electric vehicle.

The plug-in police car is the result of a combined effort started more than two years ago by a fellow named Richard Oglevee. Oglevee heads a company in Pennsylvania's Fayette County called United First Responders LLC. First Responders makes all sorts of equipment for die military and emergency personnel, including training and fire equipment. Oglevee, a volunteer fireman himself for 37 years, came up with the idea of converting a conventional 2000 Chevy Impala to an all-electric vehicle.

Oglevee persuaded the Connellsville Police Dept. to provide him with a used patrol car that was about to be retired from its fleet. The car was turned over to Oglevee and a company called Coherent Systems International Corp. was given permission to convert it from a standard internal combustion system to an all-electric vehicle. Coherent Systems has electric vehicle experience dirough their work with a company called American Electric Vehicle in a project for the military's Special Forces. The agreement was that the Connellsville P.D. would run the electric patrol car in actual police shifts for diree years, dien evaluate the results.

The challenge was to convert the Impala over to all-electric while retaining the capability to do whatever a standard gasoline-powered patrol car does over the course of an eight-hour shift. A GPS monitor was installed on a standard cruiser and data was recorded regarding what the cruiser does during the shift. The engineers at Coherent Systems then went to work gutting the powerplant out of the Impala and installing all-electric equipment.

Coherent Systems project manager and systems engineer Jack Fagan determined the electric patrol car needed to be able to run for eight hours on a twohour charge from a 240-volt outlet similar to the outlet used for a home electric clothes dryer. In a pinch, a 110-volt outlet could be used for a slow charge. The goal was to create a car that would need only normal maintenance on brakes, rotors and tires and be equipped with a battery that would last five years.

Bob McGowan, vice president and general manager of Coherent Systems, which actually designed and built the car, said the cost to run a car on gasoline during an eight-hour shift is between $3 and $4. The cost of running an all-electric for eight hours works out to be about 35 cents. Unlike some other electric vehicles, this one does not lag when the accelerator is floorboarded.

The batteries in the police cruiser are lithium-ion polymer batteries made by LG Chem. There are a total of nine batteries that deliver 27.4 kilowatt-hours and are air-cooled. Battery packs were supplied by American Electric Vehicles. The transmission is a Honda Civic SI transmission that has been modified to optimize the gearing and produce a single-speed transmission.

An AC 150 EV Power System from AC Propulsion powers the vehicle. With a vehicle weight of 2430 lbs. (after removal of the motor, transmission, exhaust system and gas tank), the AC 150 provided the necessary power required to move the Impala. Fagan reports that the AC150 system delivers up to 15OkW (200 hp) motor output, yet maximizes vehicle operating range with high efficiency over a broad operating range. Comprehensive energy recovery is achieved through traction-controlled regenerative braking. The copper-rotor induction motor weighs 50kg (110 lbs.), including its cooling system, and produces 225 N-m (165 ft.-lbs.) of torque from 0 to 5000 rpm. The power electronics unit (PEU) weighs 30kg (66 lbs.), including the cooling system, and houses the traction motor inverter, 20kW bidirectional charger/grid interface and 100-amp, 13.5V accessory power supply. The 100-amp, 13.5V accessory power supply was beneficial for the police suite of equipment.

Oglevee says they really don't know yet how fast the car will go. They're planning to run it at wide-open throttle on a seven-mile section of soon-to-becompleted highway. So far, Oglevee said, the car has been run only at 127 mph at half-throttle. He's optimistic that top speed will be comparable to that achieved with a gasoline version.