Although electric vehicles are primarily powered by high-voltage traction battery packs, 12V batteries also play a crucial role in their operation. These 12V batteries are responsible for powering various low-voltage electrical systems in the vehicle, ensuring the functionality of essential components even when the main traction battery is not in use.

In an electric vehicle, the 12V battery serves as the power source for the vehicle's auxiliary systems. These include the vehicle's lighting system, such as headlights, taillights, and interior lights; the infotainment system, including the radio, navigation, and display screens; and the vehicle's control modules, which manage functions like power windows, door locks, and climate control. Without a reliable 12V battery, these systems would not be able to operate, severely limiting the usability and comfort of the vehicle.

One of the key functions of the 12V battery in an electric vehicle is to provide the initial power required to start the vehicle's high-voltage systems. When the driver turns on the vehicle, the 12V battery supplies the power needed to activate the battery management system, the electric motor controllers, and other critical components. Once the high-voltage traction battery is online, it can then take over most of the power demands, but the 12V battery remains essential for maintaining the operation of the low-voltage systems.

12V batteries in electric vehicles also serve as a backup power source. In the event of a failure in the high-voltage system, the 12V battery can provide enough power to keep the vehicle's essential safety systems, such as the brakes and steering assist, operational. This ensures that the driver can safely bring the vehicle to a stop in case of an emergency.

Modern electric vehicles often use advanced 12V batteries, such as absorbed glass mat (AGM) or gel batteries. These types of batteries offer several advantages over traditional flooded lead-acid batteries. AGM and gel batteries are maintenance-free, have a longer lifespan, and are more resistant to vibration and extreme temperatures. They also have a higher charge acceptance rate, allowing them to recharge more quickly when the vehicle's alternator or regenerative braking system supplies power.