A rear view of an ID.4 in Dusk Blue Metallic at a charging station being charged by a woman.
Intro to Electric Vehicles

How do electric vehicle batteries work?

Intro to Electric Vehicles

How do electric vehicle batteries work?

4 minute read

Think of the power of your smartphone battery, multiplied by thousands

The battery system in an electric vehicle may be a distant cousin to the one in your smartphone, but it packs a lot more power and serves a very different purpose. If you’re wondering just what EV batteries do and how they do it, these key facts can help.

EV batteries drive the motor; the motor drives the wheels.
Electric vehicles carry a large battery pack (made of lithium-ion batteries, in most cases) that sends power to an onboard electric motor. The motor then drives the vehicle’s wheels to get you down the road. Separately, there’s an auxiliary battery that delivers power for vehicle accessories like heating and air conditioning.

EV batteries get charged in the same way as your phone, kind of.
You charge an EV by plugging the vehicle into a charging unit. Except this charger isn’t like that smartphone power cord, the one you can never seem to find when you need it. EV charging is often done either through a professionally installed home system like a Level 2 wall boxOpens an external link or a public charger like a Level 3 DC fast charger. EVs can also be charged by using a standard US electrical outlet, though charging through this method is significantly slower than using a Level 2 or Level 3 charger.

EV batteries work like every other battery cell.
Time to put on your physics hat, just for a minute. Each EV battery has two electrodes—the cathode (positive) and the anode (negative)—and a chemical substance between them called an electrolyte. When connected to an electric circuit, electrons travel from the anode to the cathode via the electrolyte. Ions, meanwhile, flow in the opposite direction, which creates an electric current. Physics lesson completed.

An EV converts AC to DC.
When you charge an EV from a standard U.S. electrical outlet, the electricity is delivered as alternating current (AC). EV batteries, however, operate on direct current (DC). Electricity from the outlet has to be converted to DC; this happens through the vehicle’s onboard converter. How long it takes to charge an EV is dictated by the fact that the converter can handle a certain amount of current at a time.

EV batteries store a lot of energy.
The battery pack in the Volkswagen ID.4 electric SUV holds 82 kilowatt-hours of energy. Given that the average U.S. home uses around 30.5 kilowatt-hours of energy a day, according to federal energy data, the amount of energy in an ID.4 battery pack is enough to power a home for about two-and-a-half days. To put it a different way: Imagine the power of a typical smartphone multiplied by 5,500.

EV batteries get re-energized when you brake
In an EV, braking actually restores energy to the battery. When you use the brake, or even take your foot off the accelerator, the vehicle stores excess energy for later use. It’s called regenerative braking, and it works by reversing the flow of energy: The vehicle’s slowing wheels turn the electric motor, which channels energy back to the battery.

An EV tells you when the batteries are low on power.
Just like a conventional gas-powered vehicle, an EV will warn you when it’s running low on power. The ID.4 has an onboard Battery Management System (BMS) that automatically helps protect the battery when it starts to run low, by switching to energy-saving mode.

An EV can start in cold weather with no problem.
Gas-powered vehicles aren’t the only ones designed to start easily in the cold. Technology in the ID.4 helps optimize heating efficiency while reducing the impact of cold temperatures on the vehicle. In other words, the vehicle prepares for those chilly winter mornings, just like you do with your first cup of coffee.

An EV battery pack is designed to last for many years.
EV batteries are built to provide usable power over many years of vehicle ownership. While a battery’s charging capacity can diminish over time, the battery in the ID.4 uses smart strategies like liquid cooling, energy reserves, and other processes to help preserve battery life.

A battery warranty helps bring peace of mind.
Along with Carefree Coverage, ID.4 owners get the benefit of a High Voltage Battery warranty that covers eight years or 100,000 miles (whichever occurs first)⁠.

The future of electric is here.

The Volkswagen ID.4 EV is truly something to behold. With a striking, aerodynamic road presence and a spacious, comfortable interior, it'll transform how you think about electric cars. Best of all? You can reserve it right now.