We are not going to mince words here: we are on the cusp of a monumental push by global automakers to bring electric vehicles (EVs) to market. They have quite a history
, but our current energy situation means we need them now more than ever.
ZENN Electric Car
DriverSide explains what’s behind the technology and what it has to offer.
How Do Electric Cars Work?
There are overarching EV categories, all using electricity in some capacity to power the vehicle.
1. Battery-Electric Vehicles (BEVs), or pure electrics: Their main energy source comes from batteries. These can be plugged-in to recharge the battery and examples include the Tesla Roadster and neighborhood electric vehicles (NEVs) such as golf carts.
2. Parallel Hybrids: Currently your most recognizable type of partially electric vehicle, these have a combustion engine that is mechanically connected to the wheels and can provide power from the engine when necessary to move the vehicle. In essence, the electric motor and combustion engine work together (in parallel) to power the vehicle. The Toyota Prius is considered a parallel hybrid and we generally separate these cars from other EVs due to their different capabilities.
3. Range-extended Electric Vehicles (REVs), also known as serial hybrids: The combustion engine acts only as an on-board generator and is completely disassociated from the drivetrain, unlike current hybrids. While there are not any on the road at the moment, 2010 should see many making an appearance
To put it quite plainly, an electric car uses electricity to move an automobile’s wheels. Despite our lack of production EVs, the technology is actually far simpler than an internal combustion engine. Looking under the hood, you’ll immediately notice the differences. Belts and hoses are replaced by high voltage wires under the hood. And of course, for the battery electric vehicles, the gasoline engine is gone. In its place is the controller, which, as its name suggests, controls the electricity that moves the car. The controller sends power from the batteries to the car’s electric motor, which then converts the battery’s electric energy into kinetic energy to provide the power that makes you go. Turning the key in the ignition connects the batteries to the controller, giving the motor the juice it needs to get things moving.
The term “gas pedal” seems a bit of a misnomer in an electric car since it actually controls variable resisters, which tell the controller what to do. If you floor the accelerator, the controller simply sends all voltage to the motor. Taking your foot off means the motor receives zero volts, and pushing anywhere in between will return a variable amount of power. An electric water heater for the heat, and electric air conditioning unit, and “gas” gauge that displays the battery charge instead of gas level are just a few other features to which you may be unaccustomed.
Unfortunately, battery power has long been the thorn in the electric car’s body panels. The very toxic lead-acid batteries, like the ones found under the hood of current combustion engine cars and are still used in some NEVs are heavy and lack the energy density required to provide the kind of driving range consumers expect to migrate over from gasoline powered cars. Not many people are going to buy a car that has a driving range of just 50 miles. Road trips aren’t an option. And what if you are stuck in particularly horrendous traffic?
Some hybrids, like the Prius, and the GM’s second generation of the EV-1 use nickel-metal-hydride (NiMH) batteries, the same batteries found in electric toothbrushes and power tools, as their energy source (the first generation EV1 was powered by lead acid batteries). While these are comparatively longer lasting than lead-acid batteries, they are still toxic and have a “memory” that shortens their life as they are subjected to partial discharges and recharges.
The acceptance of lithium-ion batteries has taken some of the worry out of the equation. These have been powering your laptops and iPods for a while now, but they are just starting to make the transition into cars. The lag has been mainly because of their expense. These power sources degrade, are sensitive to higher temperatures and have to have a dedicated onboard computer to manage the whole shebang, which increases the cost even more. However, for powering EVs, the lighter lithium-ion batteries lose less charge over time and store energy more efficiently than lead-acid ones. And most importantly, they have no memory effect (you don’t have to let them run down completely) and are non-toxic, unlike the others.
To recharge the batteries on an electric car, you simply plug it in. Filling up the “tank” usually takes about eight hours on 110v (your standard U.S. wall outlet), but some can be close to full after four on 70 amp 220v circuit (like the dryer circuit in your garage). Put in an even higher voltage charging station in your garage (100+) and the time to full can be decreased considerably. Additionally, many EVs have roof-mounted solar panels available - though cars generally don’t have enough real estate on their roofs to power anything but accessories.