Understanding plug-in hybrids

February 11, 2010
Plug-in hybrid electric vehicles (PHEVs) are coming, and fast, but how do you find the good ones and what makes them so different from traditional hybrids? The answer lies in the proportion of gas vs. electricity.

Getting best bang for your buck

If you’re looking to get the most bang for your buck, try to find a PHEV where the electric motor does all or most the driving. It should be able to reach 55 mph or greater without help from the combustion engine. Also try to make sure the range is at least 40 miles, or your normal commute. Otherwise, the plug-in feature will be much less meaningful.

Unfortunately, most of these features will probably only come in a series hybrid. I recommend BYD’s (Build Your Dreams) F3DM.

In a true series hybrid, the electric motor does all the work. A typical (parallel) hybrid uses the engine and electric motor side by side. As a result, you’ll be using both gas and electricity.

Series Plug-in Hybrids

It is the series hybrids that can greatly reduce, if not eliminate, gas needs. This is because the engine is simply an extension of an electric vehicle (EV).

In a true series hybrid, only the electric motor drives the vehicle. The engine generates electricity for the battery and electric motor, like a standby generator. You shouldn’t use any gas if you don’t travel far. It doesn’t matter how fast you go. It’s an extended range EV.

What’s Available?

BYD’s F3DM and GM’s Chevrolet Volt are examples of series hybrids. Besides these, there doesn’t seem to be any true series PHEVs available that don’t use the engine for higher speeds.

The BYD F3DM can work as a series-only hybrid OR a parallel hybrid. Hence the “DM” indicating the dual mode ability of their new F3 model. The Volt is a true series hybrid as far as I know, but it’s also an expensive luxury car.

Typical Plug-in Hybrids

Most up coming plug-in hybrids will be like an extension of a parallel hybrid, like the Toyota Prius. They’ll have a slightly larger battery and electric motor. These hybrids can reduce your gas needs, but not eliminate them. Check out a list on Eartheasy.

A good PHEV should closely resemble a series hybrid. This is why the battery is larger. You plug in your vehicle and let it charge. You don’t plug in a traditional hybrid because the battery is tiny.

Typical Parallel Hybrids

Traditional hybrids use a system of combined electric and gas power, but unequally. The electric motor is typically used for easy acceleration and coasting in low speed city roads. It’s the engine that does most of the work on the open highway. That’s because the battery and electric motor are small.

If you drive faster than about 30 mph, the engine takes over. Once it does, it will start charging the battery and driving the vehicle. It can save on gas, but not as much.

The focus of older hybrids was to make gas vehicles more efficient. The focus for PHEVs should be to give electric vehicles a longer range using gas. If you buy a PHEV, try to make sure its electric motor attributes outweigh its combustion engine attributes.