Not all of the hybrid cars on the market are of the plug-in variety. For example, a “full hybrid” is a car like the Toyota Prius which, at low speeds, it runs on only the electric motor that it is equipped with. When the vehicle goes over a certain pre-determined speed, the internal combustion engine kicks in and away you go.
A full hybrid never uses any electricity from the electrical grid. A plug-in uses the internal combustion engine only as a back-up in case the electric motor runs out of battery power, regardless of the speed that it is traveling, and it uses electricity from the electrical grid when it is being charged.
Most plug-ins have a range of about 30 miles before the battery runs out of power and the combustion engine kicks in.
How Do They Work?
As noted above, a plug-in hybrid has two means of propelling it forward – an internal combustion engine (like a regular car) and an electric motor that runs on a battery. After each use, the car is plugged into a household current and charged. If you forget to plug it in or end up with a dying battery while on the road, the internal combustion engine will kick in to power the vehicle. You can keep driving and the internal combustion engine will charge the battery. At this point, the plug-in hybrid is acting like a standard or full hybrid.
Because they reduce emissions and gasoline use so drastically, many people are hoping for plug-in hybrids to become more widely available and affordable. But the enormous cost of the lithium-ion batteries required to run the plug-ins makes them somewhat cost prohibitive. The Chevrolet Volt is said to require a 400-pound battery. Technology in this field is advancing however, and hopefully within several years will make these batteries much more cost effective for the average consumer.
Plug in hybrid cars are laid out like other hybrids in that they have a continuously variable transmission (CVT) that makes the transition from combustion engine to electric motor smooth. Plug-ins, like other hybrids, also shut off automatically at stop lights and start again when the driver takes his or her foot off the brake pedal. This reduces energy loss during idling.