In the beginning of the modern electric era, there were Hybrid Electric Vehicles (HEVs)
You may recall the Toyota Prius when it first came out. It had both mechanical (gas engine) and electric (battery) propulsion, and it was able to automatically flip back and forth between those two power sources or combine them for extra oomph when it was needed. This was a smart innovation. Electric motors can generate maximum torque (oomph) at any speed, which means they are unsurpassed for accelerating a car from a standstill or at low speed. In contrast, an ordinary gas car (internal combustion engine or ICE) develops more power the faster the engine is turning, and therefore delivers maximum power only when the engine is fully revved up.
To enable a regular engine to accelerate a car from a standstill requires an elaborate series of gears (the transmission) to match the car’s speed to the required spinning speed of the engine (RPMs or revolutions per minute). A hybrid electric vehicle (HEV) like the original Toyota Prius taps into the best of both worlds. It combines the low-speed efficiency of an electric motor with the high-speed output of a gasoline engine. Furthermore, an HEV can regenerate power (charge the battery) whenever it is coasting or going downhill. Unlike a conventional vehicle—which turns any deceleration into waste heat—an HEV can recover some power whenever stopping for a stop sign, going downhill, or braking for any reason. This not only eliminates most of the wear and tear on the braking system, but the resultant battery boost and inherent hybrid efficiencies enabled the Prius to achieve fuel economies that were previously unimaginable.
Next there came Plug-In Hybrid Electric Vehicles (PHEVs)
It didn’t take too long for car manufacturers to figure out that by putting a little bit bigger battery in an HEV one could drive solely on the battery for at least short distances, as long as the battery could be recharged when the vehicle was not in use. (See Challenges of Charging.) A gas-electric hybrid car that can be plugged in when not in service is called a PHEV. The beauty of a PHEV is that one almost never has to worry about running out of fuel because the car can take either gas or electricity. Run the battery down and the car continues on gas. Run the gas tank empty and the car continues on the battery. At some point it would be wise to refill both of them!
Then along came Battery Electric Vehicle (BEVs)
The Tesla was the first widely available electric vehicle with no gas engine, sometimes called a “pure” or battery electric (BEV). BEVs are solely electric. As Tesla points out, when they took the gas engine out they removed 2000 moving parts and replaced them with 17. This not only saves a lot of weight and expense (and carbon footprint), it also enormously reduces the maintenance requirements of the car. No engine coolant, no oil changes, no belts to replace. There are now Teslas that have been in service for more than 500,000 miles with the original batteries and almost no repairs. Heavy-duty electric motors have one moving part and should easily outlive their owners. BEVs are simple, reliable, and durable. They accelerate faster than any comparable gasoline car, are miraculously quiet, and they don’t stink up the neighborhood with exhaust (there is none at all).
By Gordon Rodda and Sarah Kelly
Which EV is right for me? Check out our Four Corners EV Buyers Guide. (Coming Soon!)