Understanding Electric Vehicle Battery Terminology

As electric vehicles (EVs) continue to gain traction in the automotive world, understanding the terminology associated with their batteries becomes increasingly important. This article aims to demystify some of the most common terms and concepts you’ll encounter when researching EVs.

1. Lithium-ion Batteries

   Lithium-ion batteries are the most widely used battery technology in today’s electric vehicles. There are two types of lithium-ion batteries, NMC and NMCA.

   • Nickel, Manganese, Cobalt (NMC)
   • Nickel, Manganese, Cobalt, Aluminum (NMCA)

   These batteries boast higher energy densities, meaning they can store more energy for their weight or volume. Other battery types such as lithium-ion phosphate, are found elsewhere in the world, but their lower energy density mean they need to be bigger which is something most automakers want to avoid.

2. Solid-state Batteries

   Solid-state batteries are an emerging technology that promises higher energy densities and faster charging times compared to traditional lithium-ion batteries. Instead of using a liquid electrolyte, as in lithium-ion batteries, they use a solid electrolyte, which can also further reduce the risk of fires and improve overall battery performance. However, their cost is prohibitive at the moment for mainstream vehicle production. On the other hand, current solid-state batteries can often top 1,000 km of range, so there is certainly interest in further developing the technology.

3. Other Upcoming Battery Technologies

   Research is ongoing into alternative battery technologies that might offer advantages over current lithium-ion batteries. Some of these include lithium-sulfur, lithium-air, and flow batteries. Each has its own set of potential benefits and challenges.

4. Battery Capacity vs. Useful Capacity

   • Battery Capacity: This refers to the total amount of energy a battery can store. It’s often measured in kilowatt-hours (kWh).
   • Useful Capacity: Not all of the battery’s capacity is used in order to prolong its lifespan. The useful capacity is the portion of the total capacity that’s available for regular use.

   This is why you may see a particular electric vehicle have a 106-kWh battery, but then read that it has a usable capacity of 101.4 kWh. That’s because it is not advisable to use the full 106 kWh of energy stored in the battery and automakers engineer limits to prevent that from happening. So, in the example above, the 106-kWh battery is designed to have just 101.4 kWh of energy that can be used. Once that limit is reached, the vehicle will no longer function to protect the battery even if there is still 3.6 kWh of energy in the battery.

5. Voltage: 400-volt vs. 800-volt Systems

   Voltage in an EV battery refers to the potential difference between its two terminals. Higher voltage systems, like 800-volt, can often charge faster and deliver more power than 400-volt systems. The direct benefit here is that you can access faster charging stations, such as 200 kW or even 350 kW stations. They are also faster to charge all things being equal. Although usually found on more expensive electric vehicles, 800-volt systems are starting to find their way into more accessible models, and this should be something potential EV buyers look at when making their final decision.

6. kW (Kilowatt)

   A kilowatt is a unit of power. When referring to EVs, it often denotes the power output of the vehicle’s motor or the charging speed of a charger.

7. kW vs. Voltage

   While kW indicates the power of a system, voltage represents its electrical potential. In EVs, a higher voltage can lead to faster charging times and better performance. However, the actual power (kW) delivered also depends on other factors like the current.

8. Other Noteworthy EV Battery Technologies

   • Battery Management Systems (BMS): These systems monitor and manage various aspects of the battery, such as its temperature, voltage, and overall health, ensuring safe and efficient operation.
   • Regenerative Braking: This technology allows EVs to recover energy during braking and feed it back into the battery, extending the vehicle’s range.