The future was here a hundred years ago. Too many people think electric vehicles are new and unique and the natural progression from hybrids. What many people overlook is that cars like the Baker Electric (Fig. 1) were quite popular in the early 1900s. The top speed was about 22 mph. Jay Leno, host of The Tonight Show, owns one that is still operational.
There were even early hybrids before gas engines and cheap gasoline pushed out the electrics. Yet early electric cars, batteries, and chargers were quite advanced. The land speed record was held at one time by Walter Baker’s electric Torpedo. It hit 75 mph in 1902. It was also the first car to have seat belts.
Edison developed a nickel-iron (NiFe) battery with characteristics similar to lithium-ion (Li-ion) in terms of energy density and cost, although nickel is a bit pricier these days. These batteries can last for decades, and many have.
Fast forward to 2010, and every major car manufacturer has a glut of gas vehicles, a smattering of hybrids, and promises of electric cars. Upstarts like ZAP (Zero Air Pollution) and Tesla are forcing their hand (see “Electric And Hybrid Vehicle Technologies Charge Ahead”).
Of course, there are many other advantages to electric vehicles such as a lower center of gravity since batteries are often stored under the floor. One of the challenges today, though, is the availability of charging stations. In the early days, places like New York City had charging stations located throughout their limits.
THE CONTENDERS
ZAP has been turning out a range of electric vehicles for years. Its Zaptruck XL (Fig. 2) and matching Zapvan Shuttle have found quite a following even with their somewhat limited range of 25 miles. The Zaptruck XL comes in two configurations.
The lead-acid battery version has the 25-mile range and a top speed limited to 25 mph, although it’s rated and licensed to 40 mph. It uses a dc motor. Switching to Li-ion doubles the range—and the price of the batteries. The platform also switches to a more powerful ac motor. Regenerative braking is possible with this package, further extending the range.
Why two configurations? These vehicles tend to be a part of large fleets such as delivery trucks. The entire round trip for a day is often well under 25 miles, so the lower-cost solution is often sufficient. Likewise, much of the travel stop-and-go is ideal for electric vehicles of either configuration, but the worst case for gas vehicles. Recharge time is only one hour, and it’s even possible to swap batteries if necessary.
Convincing fleet owners to switch to electric vehicles is usually much easier than convincing consumers to switch because fleet requirements are typically well known and tracked on a regular basis. It is simply a matter of looking at the requirements, the performance of the vehicle, and the associated costs to see whether electric is more economical than the alternatives.
Consumer use, on the other hand, can be extremely variable—hence the initial assumption that a gas vehicle, with a longer range, will always be the best alternative. The average range required by most consumers on a daily basis is about 33 miles, which is well under the limit of most electric vehicles. The problem is that most consumers do not realize this or do not want to contend with planning for longer treks.
Consumers looking for a slick but inexpensive electric solution need look no farther than the ZAP Alias (Fig. 3). This three-seat, three-wheeled car is very stable. It will hit 60 mph in 7.8 seconds and has a top speed just over 100 mph. Also, it has a minimum range of 100 miles. At $35,000, it is on par with other electric cars in this market. And, it can be charged from a 110-V outlet.
The Li-ion battery packs (Fig. 4) sit under the passenger cage. The 216-V ac induction drive motors are in the front wheels. The frame includes a roll hoop. Also, the car has a double wishbone suspension system and Lambo style doors. The control electronics may be advanced, but the schematic for the Alias, like most electric vehicles, is very simple. Still, battery management and charging remain a significant portion of the system.
Another three-wheeled electric car in this class, the Aptera 2 from Aptera Motors, has a 100-mile range. A hybrid version has a 50-mile electric range and 350-mile gas range. Its aerodynamic design has a Formula One-inspired passenger safety cell, recessed windshield wipers, and low rolling resistance tires. It also uses boxed sandwich foam core composite structures and has a 45-in. front crumple zone. The Series 2 will use lithium-iron-phosphate batteries.
The Tesla Motors Roadster Sport (Fig. 5) is at the other end of the cost spectrum. It starts at $128,500 but will hit 60 mph in 3.7 seconds. It’s a high-performance sports car from the ground up. The car has a custom tuned suspension with driver-adjustable dampers and anti-roll bars. It also has forge alloy wheels.
Tesla spent a lot of engineering time and talent creating the motor and battery system. The hand-wound stator has a high density winding for lower resistance. It also has a higher peak torque that delivers the kind of performance expected from such an expensive vehicle.
The 375-V, three-phase, four-pole, ac induction electric motor in the Sport is air-cooled and has a peak of 288 horsepower. It weighs less than 70 lb and redlines at 14,000 rpm. The Power Electronics Module (PEM) is smaller on the latest incarnation.
The six-figure price also delivers a stylish interior and exterior with a resin-bonded and riveted extruded aluminum monocoque. The four-wheel independent suspension features upper and lower unequal-length wishbones with co-axial coil spring telescopic dampers.
The Sport has a 236-mile range. The battery pack is designed to last for seven years or 100,000 miles. The water-cooled microprocessor-managed battery pack has 6831 individual cells. It can be charged in 3.5 hours using a 240-V, 70-A supply.
Tesla Motors does not expect to sell a large number of Roadsters given the price, but the company does expect them to be profitable. Tesla also has been delivering Roadsters. The more affordable Model S (Fig. 6), set to be delivered in 2012, uses a 9-in. water cooler motor.