An electric vehicle’s most significant, most important, and most expensive component is its high-voltage battery pack. Many newer electric vehicles (EVs) are designed around their battery pack, with some even incorporating it as an integral part of the chassis structure.
This battery pack must store vast amounts of electricity required by an EV to provide enough power for daily driving and ensure a sufficient range, minimizing charging anxiety for owners.
The Role of the High-Voltage Battery
The high-voltage battery, also known as the traction battery, is the powerhouse of an EV. It stores dozens of kilowatt-hours (kWh) of electricity and operates at 400 or even 800 volts.
This high energy capacity can provide hundreds of miles of range and excellent acceleration, power household appliances for about a week, or support power tools for many hours through bidirectional charging.
Despite the massive power of the high-voltage battery, EVs still require a small 12-volt battery similar to those in conventional combustion cars. To understand why, we must delve into car batteries’ history and evolution.
A Look Back at Car Batteries
Cars have been around for over a century, initially without batteries. Early cars used a magneto, which generated electricity needed to power ignition coils and spark engines as long as the engine ran.
However, by the 1930s, the hand crank was considered outdated and dangerous, leading to the introduction of electric starters powered by onboard batteries.
Initially, these batteries had 6 volts, but by the 1960s, the industry-standard shifted to 12 volts to crank larger engines more effectively.
The 12-volt battery became essential for powering a car’s ignition system, and once the engine started, it was recharged by the alternator, powering all electrical systems in the vehicle.
Why EVs Need 12-Volt Batteries
Unlike their internal combustion engine (ICE) counterparts, electric vehicles do not need a 12-volt battery to crank an engine. However, they still require a 12-volt battery for several critical functions:
- Powering Auxiliary Systems: The 12-volt battery powers essential systems like lights, door locks, electric power steering, infotainment, and safety systems. These systems, borrowed from traditional combustion engine cars, typically operate at 12 volts.
- Waking Up the Vehicle: When an EV is turned off, its high-voltage traction battery is disconnected to prevent power leakage and ensure safety. The 12-volt battery powers the electrical contactors (electrically controlled switches) that reconnect the traction battery when the vehicle is turned back on.
- Regulating Voltage: Like an ICE vehicle, the 12-volt battery helps regulate voltage and provides additional power when needed.
The Unique Role of 12-Volt Batteries in EVs
In an EV, the 12-volt battery serves functions similar to an ICE vehicle’s battery but operates differently. It does not need to provide a burst of power to start an engine; instead, it maintains lower power systems.
A DC-to-DC converter steps down the voltage from the high-voltage battery to recharge the 12-volt battery, replacing the role of an alternator in an ICE vehicle.
When an EV is parked for an extended period, it periodically wakes up to recharge the 12-volt battery, ensuring it does not deplete.
If the 12-volt battery fails, the vehicle may not unlock or start, even if the high-voltage battery is fully charged.
How Long Does an EV’s 12-Volt Battery Last?
The lifespan of a 12-volt battery in an EV is similar to that in an ICE vehicle, typically lasting three to five years. Factors influencing battery life include battery quality, driving habits, climate, and maintenance.
What Happens When an EV’s 12-Volt Battery Dies?
A dead 12-volt battery in an EV can lead to various issues, such as the vehicle not starting, power doors not working, or lights not turning on.
This can be due to the constant power demand from various computer systems even when the vehicle is off. A dead battery can also result from a malfunctioning low-voltage charging system or a failing one.
How To Know if the 12-Volt Battery on an EV Is Going Bad
Signs of a failing 12-volt battery include dashboard warning lights, dimming or flickering lights, or malfunctioning accessories. If the battery repeatedly dies after being charged, it’s likely time for a replacement.
EV 12-Volt Battery Maintenance
Maintaining the 12-volt battery in an EV involves similar practices to those in an ICE vehicle:
- Clean the battery, terminals, and cables annually.
- Ensure all ground wires and cables are clean and tight.
- Secure the battery correctly.
- Replace the battery if it’s damaged or leaking.
- Use a battery maintainer if the EV sits for extended periods.
Wrap up
While the high-voltage battery in an EV gets most of the attention, the 12-volt battery plays a crucial supporting role. It powers essential systems, maintains safety features, and ensures the vehicle can start and operate correctly.
Understanding the importance of the 12-volt battery and how to maintain it can help EV owners keep their vehicles running smoothly and avoid unexpected issues. As EV technology continues to evolve, the role of the 12-volt battery remains a vital component of the overall electrical system.
