Hybrids: What is the Difference Between Traditional and Plug-in?
— Updated November 2015
Hybrid vehicles have become a very popular topic over the last few years. As hybrids continue their march towards mainstream adoption the amount of questions that are asked increase as well. The most popular question being, “What is the difference between a hybrid electric vehicle (HEV) and a plug-in hybrid electric vehicle (PHEV)?”
To answer this we can start with what is the same. Both hybrid vehicles use two propulsion methods, an internal combustion engine and an electric motor. The vehicles rotate between the two methods depending on the situation, and in times when extra power is needed they will draw from both sources. However, the key differences between the two systems are the primary source of energy and the overall energy efficiency of the two vehicle architectures. Let me elaborate below.
Hybrid Electric Vehicles (HEV):
At low speeds a hybrid will usually draw its power from the electric motor. When drivers increase speed they are calling on more power to propel the vehicle forward. To generate this increased need for power, the hybrid will switch to its internal combustion engine (ICE). This change causes the vehicle to shift from electric power to gasoline power. If the vehicle still needs more power (to scale a steep hill) both propulsion systems will work simultaneously to provide an added boost.
The main fuel source for these vehicles is still gasoline. However, the amount of gasoline required is notably less relative to a purely ICE vehicle. This is because the electric motor uses regenerative braking to capture energy and store it in the on board batteries. This stored energy is then used to provide power to the electric motor.
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Plug-in Hybrid Electric Vehicles (PHEV):
A plug-in hybrid uses its electric motor to power all aspects of propulsion. The vehicle will continue to use the electric motor until battery levels reach a predetermined battery state of charge (SOC). At this SOC level, the vehicle enters into a charge sustaining mode. The internal combustion engine, in some cases acting as a generator, then kicks in to supply power to the electric motor. A plug-in hybrid is essentially an electric vehicle that can call on gasoline to extend its range.
While in charge depleting mode, the main fuel source for PHEVs is electricity since they used stored energy that was sourced from the electricity grid. While PHEVs also take advantage of regenerative braking, the energy captured is not enough to sustain the electric motor as the main driving system.
Which is more efficient?
With more and more plug-in hybrids and battery electric vehicles (BEVs) hitting the market, the financial case is shifting away from hybrid vehicles. For example, according to InsideEVs, a 2016 Toyota Prius hybrid HEV would have to drive 242 miles before overtaking the Chevy Volt plug in hybrid in fuel efficiency, and is always less efficient inside 100 miles.
The Top Selling Hybrid and Plug-in Hybrid Models of 2015
We’ve put together a simple graphic showing the top 5 selling models of 2015. Just click the big box below to view it!
Monitoring Hybrid and Electric Vehicles
There are many aspects of electric vehicles and plug-in hybrids that are useful to monitor that are different from conventional vehicles such as battery SOC, electricity usage, and charging behaviors. FleetCarma has developed a monitoring system that was specifically designed and build for these advanced vehicle technologies, we call it electric vehicle monitoring.
Interested in monitoring your electric vehicles? Contact us to get a demo.
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