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Understanding Electric Vehicles: The Basics

April 14, 2020

Electric cars are becoming increasingly commonplace. These days, even in the middle of rural America, you’ll likely see a Tesla Model S humming around. Yet most people don’t understand how pure electric vehicles (EVs) work.


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How electric vehicles (EVs) work

Beneath the surface, electric vehicles are very similar to full hybrid vehicles. The primary difference is that a gasoline engine charges the battery of a hybrid, while an EV must rely on an outboard charger to replenish its battery.

Otherwise, hybrids and EVs share many of the same primary components, such as a high-voltage battery, inverter and electric motor. Let’s take a look at how these parts work together to propel an EV down the road.

High-voltage battery

The high voltage (HV) battery is the heart of any EV. HV batteries are typically rated at hundreds of volts and use lithium-ion technology. The HV battery acts as a storage device for high-voltage electricity and provides power to the motors (s) as needed.

12-volt battery

Many also have a 12-volt battery to power the low-voltage electronics. For example, on the first-generation Nissan Leaf, whenever the key is in the accessory position, the 12-volt battery powers all of the car’s accessories. Once the vehicle is up and running, the DC/DC converter takes over.

DC/DC converter

In a traditional gas-powered vehicle, the alternator, which is driven off the engine, recharges the 12-volt battery. Also, when the engine is running, the alternator provides power to the car’s electronics.

But an electric vehicle doesn’t have a gas engine to drive the alternator, so a device called a DC/DC converter recharges the 12-volt battery, instead. The DC/DC converter also supplies power to the low-voltage electronics under most conditions.

To make it all happen, the DC/DC converter reduces the voltage from the HV battery to a point that the car’s 12-volt system can use. In some instances, the device is integrated into the inverter, while in other cases, it’s a stand-alone unit.

Inverter (aka power control module, controller, etc.)

One complication that arises with the design of electric cars is that the battery stores DC electricity, while the motor (s) requires AC electricity. The inverter solves this problem by converting DC power into AC power.

On many electric vehicles, the motor can also act as a generator during deceleration and braking. During this scenario, the inverter works the other way by converting AC power into DC power. The DC power helps charge the HV battery.

Also, the inverter controls the motor (s) based on the information from sensors and modules over the data network.

Electric motor (aka traction motor)

The traction motor converts the electrical energy from the battery into the rotational force needed to drive the car’s wheels. Most electric vehicles use a single traction motor, though some use one at each axle for all-wheel drive capability.

Onboard charger (aka Battery charger control module)

Since EVs do not have an internal combustion engine like hybrids do, they must recharge their battery through an external source. Most EVs can hook up to either an AC charger (120-volt or 240-volt) or a DC fast charger.

Once the car is plugged into a charging station, the battery charger control module coordinates charging operations. If the car is plugged into an AC charging station, the device will also convert the AC electricity into the DC electricity that the battery can store. 

Electric Vehicle (EV) Charging Methods

There are three types of chargers to choose from: Level 1 (120-volt AC), Level 2 (240-volt AC) and DC fast charging (480-volt DC). Level 1 is usually found in homes, while Level 2 is often found in business parking lots.

Essentially all production EVs and plug-in hybrids can hook up to a Level 1 or Level 2 charger. And all automakers (except for Tesla) use the same adapter for these lower-level charging stations. The problem is, it takes several hours to get an 80% charge using one of these devices.

Since EV batteries store DC power, a DC fast charger can provide a quicker charge. There’s no need for the EV’s onboard charger to convert the AC electricity into DC electricity. As a result, vehicles that support DC fast charging can get an 80% charge in under an hour, when using an appropriate device.

The main drawback is that not all automakers use the same style adapter for DC fast charging. There are three plug styles used by different automakers – and that can make charging a hassle.

Should You Consider an EV?

EV technology is improving all the time. When battery-powered cars were first introduced, they had a very limited range. The 2011 Nissan Leaf, for example, could only travel around 70 miles on a single charge. By comparison, the long-range version of the Tesla Model 3 can travel over 300 miles per charge.

Because the technology is advancing so rapidly, even if you’re not ready for an EV now, you may be in the near future.