Electric Car Range Demystified

Written by Bryan Johannsen

The range of a given electric car can be a tricky subject. Sure manufacturers publish a range in their specifications and advertisments but it's worth looking in to what is the difference between the advertised range of a given car and it's actual range when used outside of the testing lab.

The range number defined in the specs is usually the EPA combined number which involves changing the batteries to their maxium level then running the car until it quits under optimal conditions. This means no aggressive accelleration, no air conditioning, heating or other battery draining accessories are running and no steep hills are climbed. THe car also isn't carrying a full load of passengers.

Just like in a gasoline or diesel powered car, "your mileage may vary" depending on your driving habits. Is it summer in Georgia and you've got the air conditioning cranked up keeping the interior about the temperature of a meat locker? You won't even come close to that published mileage figure. Hauling a car load of friends around the hills of San Francisco? Again, the published range is nothing like what you'll acutally see. Aggressive accelleration isn't something one thinks of in a neighborhood electric vehicle but if you're trying to test that 4 second 0-60 time in your Tesla Roadster your range will be significantly lower than the published figure.

The test numbers are also achieved using a battery fresh from manufacture. Like any rechargeable battery the capacity for a charge declines as the battery is cycled. Depending on use and battery technology the overall range of your electric car could drop up to 20% after a few years of use.

Lastly, batteries are very rarely charged to their maximum level and run down to being completely empty. In fact this is actually bad for the battery and can significantly lower it's lifespan. The charging systems in most electric cars will charge the battery to somewhere between 85%-90% capacity and then at the lower end the car will change to a low power mode to get the car home before the charge is completely expended.

When all is said and done you will probably see around 70% of the manufacturer's specified range in real world conditions and that range will decline as the batteries are cycled.

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