Demystifying the terms and jargon around EV Batteries

Highlights :

  • Specifications of EV Batteries explained: Capacity, Energy Density, Range, Charging, Longevity
Demystifying the terms and jargon around EV Batteries

The ever-increasing craze of the adoption of electric vehicles (EVs) has led to the growth of the EV battery market as well. While the EV technology provides the latest sustainable mobility solution for customers, unlike conventional fossil fuel-run vehicles, it is unknown to many customers what specifications one needs to look at in an EV, and what do they mean. Fortunately, for any such vehicle, its battery forms the backbone. Thus, it is quite handy to have a basic handbook of specifications of EV batteries while sorting the list to buy your new sustainable ride.

Lithium-ion batteries are the most common battery types in electric vehicles. Li-ion batteries are formed with certain elements including carbon or graphite, metal oxide, and lithium salt. These elements make up positive and negative electrodes. Further, they are combined with the electrolyte, producing an electric current that makes the battery work, powering your vehicle to make the wheels turn. Now it is not some very novel technology in itself. It is the same battery that you will find in your everyday gadgets, such as mobile phones and laptops – just on a bigger scale!

The electric vehicle battery is a thing of beauty. Its 80 percent or more constituents are recyclable. So, when your battery has come to an end of its lifecycle, it can be stripped down to separate the raw materials to reuse them.

Fascinating, isn’t it? There are few more fascinating, yet important points to look for in EV batteries. Especially, at the time of buying your new EV. So, here’s a list of the most important specifications of EV batteries you need to know while choosing your ride, and simplifying what they mean.

#1 Capacity

The energy stored in a battery, called the battery capacity, is measured in either watt-hours (Wh), kilowatt-hours (kWh), or ampere-hours (Ahr). Perhaps, the most critical factor to consider amongst specifications of EV Batteries when shopping for an EV is the estimated range on a full charge. These batteries are specifically designed for a high ampere-hour (or kilowatt-hour) capacity. It is usually measured in kWh. It’s important to consider that while the kWh label represents the total amount of electricity a vehicle uses, kW reflects the rate of usage of electricity. In easier terms, how much energy will car need per unit time.

To understand what battery capacity is, let’s consider power requirement of a house. Say, a house consumes power of 2500W (2.5kW). Thus, 2.5kWh is energy requirement of each hour to run your appliances. Now consider an average battery runs for 4 continuous hours before a complete discharge. So, what will be the capacity of battery needed to do the job? In that case, if your battery goes 4 hours before a need to recharge, it must be providing a total of 10000Wh (10kWh). This is 2500W for 4 hours straight. Hence, this 10kWh is capacity of battery, whereas 2.5kW represents electricity usage rate.

#2 Energy Density

Simply, Energy density is the measure of how much energy a battery contains in proportion to its weight/volume. High energy density means the battery can deliver large amounts of current for high-power applications. In an electric vehicle, all the energy applications are fed by the same battery used for moving the vehicle. How much energy per volume or weight the battery can give also decides the range of EV as there’s only limited space or weight that an EV can concede.

Energy density is generally expressed in two ways: Volumetric energy density (watt-hours per liter (Wh/L)) and Gravimetric energy density (watt-hours per kilogram (Wh/kg)). Though, the first is more common. Gravimetric energy density can also be referred to as specific energy.

Li-ion batteries have one of the highest energy densities of any battery technology today (100-265 Wh/kg or 250-670 Wh/L). Tesla Model 3 cars have an energy density of 260 Wh/kg, one of the highest in the segment.

#3 Range

A higher range means that the electric vehicles would run more kilometers without recharge. The range of an EV depends directly on its Battery capacity. To calculate range, the battery size (capacity) is divided by the consumption. We arrive at a theoretical figure, which is what the manufacturer prints and advertises as the certified range. Yet, an EV’s actual range of charge can vary according to a number of factors.

Lead-footed acceleration or even driving at higher speeds tend to use more kWh. So does a full load of passengers and cargo. All else being equal, a heavier vehicle consumes more energy to reach and maintain a given speed than will a lighter one. In addition, weather conditions matter – it drains quickly in extremely cold or hot weather. Unlike a conventional vehicle, an EV’s climate control system relies solely on battery power.

For the 2021 model year, the median range for EVs was 234 miles against 259 miles for the 2020 model year. The median has likely dropped because of the introduction of a wide range of models with rated range of less than 250 miles. For instance, all the variants of the Porsche Taycan, the Volkswagen ID.4, the Polestar 2, and the Ford Mustang Mach-E.

#4 Charging

Charging comes down to two familiar resources: time and money. How long an EV takes to charge depends on its battery size and the voltage of the charger that the consumer uses. How much the charging costs, depends on when and where the vehicle is charged.

Depending on battery capacity it can take anywhere between 8 and 16 hours to achieve a full charge. Electric vehicles are charged at home mostly, either via a conventional 120-volt circuit (Level 1 charging) or a 240-volt line (Level 2 charging). If a local energy provider offers a discount for electricity during off-peak hours, you can save money by scheduling a charge in the middle of the night.

The cost of charging, meanwhile, depends on where the EV is driven. In addition, whether the car is refuelling during peak or non-peak hours also matters. That is, when the electricity provider incentivizes off-peak electricity consumption.

#5 Longevity

How long an EV battery lasts isn’t just a question of the daily range. The actual life of an EV battery is an important area to speculate. Longevity can be a measure of years of service of an EV battery. To that end, your car will not suffer a catastrophic battery death like an ageing mobile phone.

There are many cells in a typical EV battery. Thus, they retain capacity even after hundreds of thousands of miles. Although you can’t bet on them to perform as well as when box-fresh and new, they will be operational for many years. One can expect an electric car battery life of at least a decade. Safe to say, your car may fall apart before your battery fails!

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Junaid Shah

Junaid holds a Master of Engineering degree in Construction & Management. Being a civil engineering postgraduate and using his technical prowess, he has channeled his passion for writing in the environmental niche.