Do Electric Cars have 12V Batteries? (Lead acid vs Li-ion)

Last updated on March 24th, 2023 at 02:10 pm

Over the years battery technology is improving with pace. This has resulted in better ranges and performance in electric vehicles around the world. Earlier EVs were only imagined as vehicles for personal use. But with improved technology, we can now even see EVs in high-power categories like pickup trucks.

Do Electric Cars have 12V Batteries? (Short Answer)

Yes, many EVs have an extra 12V battery inbuilt into them. This battery is an essential part of the vehicle. As this battery is used to power the EV accessories like stereo, lights, and alarms.

Your Tesla might have the ability to drift with the dual motors but it is worthless in the absence of a 12V battery.

What is the use of a battery in your EV?

We will start with the primary reason for using these batteries. In EVs, batteries are majorly required for two purposes.

  • First is moving the vehicle forward (propulsion) which is handled by an expensive and big high-voltage battery.
  • Second is the electrical systems which require low voltage like stereo, lights, and alarms.

Note: An electric vehicle is not started up by the same battery used for propulsion. For all these purposes a 12V battery is used in the cars.

Why two different batteries are present in an EV?

You ask why? Though there are plenty of reasons to do that the primary concern here is safety. You don’t want 800 volts of charge coursing even through the systems where it is not required. When asked the Hyundai EV engineers about this, they responded that the separation allows the safe disconnection of high voltage and low voltage in the event of a crash.

The legacy situation has also a role to play in the continuing use of 12V batteries in vehicles. Since manufacturers and suppliers both know to make this 12V system work consistently and affordably. In the case of this battery drainage, it is easy to solve the problem in minutes. With all the financial constraints of an EV, it makes sense to use a 12V battery system.

How does the 12V battery gets charged?

This 12 Volt battery is not charged like the conventional batteries. The battery pack is charged by the electric vehicle itself. The electric motor’s motion during driving is used to charge this battery. They are often topped by the main battery via a converter to step down the voltage in most cars. 

In case your battery dies, the jump start is required, even in the presence of the main battery pack. The 12V battery powers the vehicle’s motor during start-up, which eventually starts the vehicle. To jumpstart the battery, the same process is followed which is used for IC engine cars.

Lead-Acid Vs Lithium-Ion Battery

Lead-acid battery
Lead-acid battery

For years the battery used for other purposes than propelling the vehicle is lead-acid ones. The simple reason is the price. They are much cheaper when compared to Li-ion batteries. The major advantages Li-ion batteries brings include compactness and lightweight (weighs around one-third of the lead-acid batteries).

Lithium-ion Battery
Lithium-ion Battery

They also have better energy retention even in conditions like cold weather. The EV giant Tesla is soon replacing the 12 V lead-acid batteries with Li-ion batteries slowly in their new vehicles. Li-ion batteries will take the place of lead-acid batteries just the way they themselves will get replaced by graphene ones. Read more on Li-ion batteries.

Will 12V battery become obsolete?

To phase out the 12V battery from the EV system, expensive engineering needs to be done. Hence it is required to find a safer way of using the main battery for this purpose. For example, one method would be the DC-DC conversion to step down the voltage from high voltages to 12V. The engineering required is enormous which seems unnecessary when there is a much cheaper and safe way available.

What are the other alternatives to a 12V battery?

It is also interesting to see whether the norm of using a 12V battery system is replaced by others say-14 or 24 or 48 Volts.  Manufacturers around the world are experimenting like the Ford Escape plug-in uses a 14.4kWh battery pack but even it powers up the lead-acid 12 volts bolted under the cargo floor.

Hyundai also tried something with jump-start by connecting the low-voltage systems to the large battery. This allows their cars to jump-start themselves by pushing the “12V Batt Reset” button on the dashboard. But the battery used for the purpose is the 14Volt Li-ion battery which is fitted inside the high-voltage battery pack.

But it looks like the 12V battery, as well as the system, is here to stay for a long time.

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Kanishk Godiyal

I have a keen passion for learning and understanding various concepts of electronics. Combining my knowledge with my SEO skills, my aim is to make electronics easy for every tech enthusiast out there.

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