Types of Electric Vehicles (in a snapshot)

EV, HEV,PHEV, MHEV

Types of Electric Vehicles

 

There are four basic types of electric vehicles:

EV

(Electric Vehicle)

  • No IC engine
  • Only electric drive
  • Battery pack size is large (20-80 kWh)
  • Example: Nissan Leaf, Tesla Model S
  • Sub-category REEV (Range Extended Electric Vehicle) like BMW i3

HEV

(Hybrid Electric Vehicle)

  • Has IC engine and electric motor
  • The batteries get charged by the engine
  • Battery pack size is medium (6-12 kWh)
  • Example: Honda Civic Hybrid

PHEV

(Plug-in Hybrid Vehicle)

  • Has IC engine and electric motor
  • The batteries can be charged from an external source (plug)
  • Battery pack size is medium (6-12 kWh)
  • Example: BMW i-8

MHEV

(Mild Hybrid Vehicle)

  • IC engine and electric motor
  • Turns off the engine and switches to motor when coasting, braking and restarting quickly
  • Cannot be solely driven on electric motor
  • Example: Chevrolet Silverado Hybrid

 

In addition to the above four types, there is another class of Electric Vehicles called that FCEV or Fuel Cell Electric Vehicle. HONDA Clarity  and Riversimple’s RASA are examples of FCEVs. These vehicles require Hydrogen as fuel. The high energy density of Hydrogen takes away the range anxiety however the capital cost and the running cost of these vehicles is prohibiting their permeation in the market.

The pure EV also has a sub category. This is called the REEV or the Range Extended Electric Vehicle. The Range Extended vehicle has a small petrol generator. The generator simply tops-up the batteries when the charge on them is running low. As the electric generator is separate from the drivetrain it can run at a constant optimal speed. Electric Generators have achieved 40% efficiency fuel-to electricity efficiency in the past. The BMW i3 is an example of Range Extended Electric Vehicle.

The IC engine efficiency (fuel to torque) is less than 15% where as an electric motor can achieve efficiency of over 85%. Thus electric drive in terms of energy conversion is more than 6 times efficient. This also tells us that even if the batteries are charged from a coal fired powered plant, the electric drive is  still greener compared to its IC engine counter parts (Petrol/Diesel cars)  Non-plug-in Hybrid vehicles are getting phased out because they do not allow the option of charging batteries from a cleaner source.

Electric vehicles can also store a portion of the energy that is lost while braking. This feature in the industry is called regenerative braking.  This further improves their drive economy.

More details on electric cars can be obtained from the following video:

Further reading:

Lowest price electric vehicle

Coefficient of Drag Story

 

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