Mastering EV battery technology for sustainability and performance

EV batteries power our journeys with clean energy but have you ever wondered how they work, how to maximise their performance and lifespan? Understanding EV batteries can help you become an efficient and eco-friendly EV driver.

Basics of EV batteries

Electric car’s motor and all the onboard electronics are powered by specialised rechargeable batteries using electricity stored in the battery. This electricity is converted into mechanical energy by the electric motor, propelling the vehicle forward.

EV batteries can be recharged from the electric grid or even from renewable energy sources like solar panels.

The battery pack is formed by numerous smaller battery cells assembled and grouped together. The brain behind the battery pack - Battery management system (BMS) - performs critical functions including tracking the battery’s voltage, current, temperature, and state of charge.

Types of EV batteries

The type of battery affects your EV’s range and performance but also its environmental footprint.

Lithium-ion batteries

Lithium-ion (Li-ion) batteries are the cornerstone of the modern EV industry, powering the majority of electric vehicles on the road today.

Pros:

• High Energy Density: Enables longer driving ranges on a single charge.
• Quick Charging: Facilitates faster recharge times, making EVs more convenient for daily use.
• Lightweight: Contributes to better vehicle efficiency and performance.

Cons:

• Temperature Sensitivity: Performance can degrade in extreme temperatures, requiring sophisticated thermal management systems.
• Ageing: Capacity fades over time and with use, although advancements continue to mitigate this issue.

Nickel-metal Hydride batteries

Before the advent of lithium-ion technology, nickel-metal hydride (NiMH) batteries were a popular choice for rechargeable applications, including early electric and hybrid vehicles.

Pros:

• Good Energy Density: Though not as high as lithium-ion, it’s sufficient for many applications.
• Durability: Resistant to overcharging and less prone to memory effect, making them reliable over many cycles.

Cons:

• Weight: Heavier than lithium-ion batteries, impacting vehicle efficiency and performance.
• Lower Energy Density: Results in shorter driving ranges compared to lithium-ion batteries.

Solid-state batteries

Solid-state batteries represent the cutting-edge of EV battery technology, with the potential to overcome many limitations of current battery types. By replacing the liquid electrolyte with a solid electrolyte, these batteries offer improvements in safety, energy density, and lifespan.

Pros:

• Higher Energy Density: Promises longer ranges without increasing the battery size.
• Increased Safety: Reduced risk of leaks and fires due to the solid electrolyte.
• Longer Lifespan: Less degradation over time and use, leading to longer-lasting batteries.

Cons:

• Manufacturing Complexity: Production processes are more complicated, affecting scalability and cost.
• Cost: Currently, high production costs limit their adoption in mainstream EVs.

Optimising battery performance

Maximising your EV battery’s efficiency, lifespan, and performance revolves around three key areas - your driving habits, temperatures and charging practices.

How your driving habits affect the EV battery

Being mindful of your driving habits can help preserve the battery’s health and extend its life.

Aggressive driving

Is your driving style rapid acceleration and hard braking? Maybe in a petrol car but not in your EV because it can drain your battery excessively and increase wear on the battery system.

Frequent driving at high speeds

Are you a regular on motorways? If you are regularly driving at speeds significantly above the average you could be reducing your battery’s efficiency over time. That’s because at high speeds the battery depletes more quickly while being under stress due to the sustained high power output.

Using air-con or heating excessively

Frequent use of air conditioning, heating, and high-speed cruising can drain the battery more quickly and put additional load on the battery. Be sensible and think twice before using any of your EV’s high power consumption features.

Inefficient route planning

You should avoid stop and go traffic, steep inclines, hilly terrain or areas with frequent stops whenever you can. It can lead to higher energy consumption and reduced battery life due to the constant demand for power.

How can temperature affect your EV battery

Temperature extremes can affect EV battery’s performance and lifespan because they impact the battery’s ability to store and release energy.

However, it’s not only the extremes that can influence battery behaviour; even moderate deviations from the optimal temperature range can impact battery performance.

The optimal temperature range

EV batteries perform best within a moderate temperature range, typically between 20°C to 25°C (68°F to 77°F). Outside of this range, even if not at extreme temperatures, the battery’s performance can begin to deviate from its optimal efficiency.

As a general rule high temperatures can cause the battery to degrade faster while low temperature reduces the battery’s efficiency (less range, slower charging).

Impact of cold temperatures

• Reduced Range: In cold weather, the chemical reactions within the battery cells slow down, reducing the battery’s ability to deliver power. This leads to a decrease in the EV’s range because more energy is required to maintain the same level of performance.
• Slower Charging Rates: Charging times can increase significantly in cold temperatures. The lithium ions in the battery move more sluggishly through the electrolyte, making it harder for the battery to accept charge quickly.
• Increased Energy Consumption: To keep the cabin warm, EVs must use energy from the battery to power the heating system, which can further reduce the vehicle’s range.

Impact of hot temperatures

• Accelerated Battery Degradation: High temperatures can cause the electrolyte in the battery to break down faster than at cooler temperatures, leading to a loss of battery capacity and a shorter overall lifespan.
• Increased Self-discharge Rates: Batteries tend to discharge themselves more quickly in hot conditions, even when the vehicle is not in use. This phenomenon can lead to a gradual loss of charge over time.
• Thermal Management System Activation: EVs equipped with thermal management systems may use additional energy to cool the battery in hot weather, slightly reducing the overall efficiency and range.

Many modern electric vehicles come equipped with thermal management systems (TMS) to regulate the temperature of their batteries, ensuring optimal performance, efficiency, and longevity. These systems can cool or heat the battery pack as needed to maintain it within the ideal temperature range.

Some notable EV brands known for their thermal management systems:

• Tesla Model S, Model 3, Model X, Model Y
• Chevrolet Bolt EV
• Nissan Leaf (from 2018 onwards)
• Audi e-tron
• Ford Mustang Mach-E
• Volkswagen ID.3, ID.4, and others in the ID. series
• Hyundai Kona Electric and Ioniq Electric
• Jaguar I-PACE
• Porsche Taycan

Best practices for charging

The key to prolonging the health and efficiency of your EV battery is understanding the balance between fast charging and slow charging, along with maintaining an ideal state of charge (SOC).

Fast charging (rapid charging)

Fast charging is a convenient way to charge your electric car, especially on long trips. However, frequent use of fast charging can put stress on the battery due to heat generation and can lead to shorter lifespan.

Slow charging

Slow charging is gentle on the battery and it’s recommended for daily use - overnight charging at home or during the day at work.

Ideal state of charge (SOC)

You can optimise the longevity and performance of your EV battery by maintaining the battery’s charge level within the ideal state of charge. The most common recommendation is to keep the battery’s SOC between 20% and 80%.

Charging your battery to 100% (unless planning an immediate use) and allowing the battery to deplete entirely increases the risk of damaging the battery’s health over time.

Charging an EV battery in various weather conditions

Heatwaves

Charging an EV during a heatwave is generally safe, as EVs and chargers are designed to operate within a broad temperature range. However, extreme heat can affect the charging efficiency and may lead to slower charging speeds, as the battery management system (BMS) works to protect the battery by regulating its temperature.

• Park and charge your EV in shaded areas
• Use the car’s thermal management system, if available, to help maintain optimal battery temperatures

Rain

Charging in the rain is safe due to the stringent safety standards that EV charging equipment must meet. Connectors and charging ports are designed to be waterproof, and there are multiple layers of protection against short circuits or electric shocks.

• It’s always wise to handle charging cables and connectors with dry hands
• Make sure that the charging port cover is securely closed after disconnecting

Snow

Charging an EV in snowy conditions is safe. Charging equipment is built to withstand low temperatures and moisture. However, cold weather can reduce charging efficiency and battery performance, as batteries are less efficient in cold conditions.

• Charging your EV in a covered area can protect the charging equipment from snow accumulation
• Preconditioning the battery (heating it up before charging) can help improve charging efficiency

Thunderstorms and lightning

Charging during a thunderstorm comes with a theoretical risk of lightning strikes. However, modern charging stations are equipped with surge protectors to mitigate this risk. It’s generally safe but if you’re concerned, you may choose to unplug during severe storms.

Floods

Avoid charging your EV in flooded areas. Submerging charging equipment or the vehicle’s electrical components in water can be dangerous and may damage the vehicle.

Repairing or replacing EV batteries

A common myth about EV batteries is that they need to be replaced frequently due to a short lifespan. However, modern EV batteries are designed to last for many years and are often covered by warranties for up to 8 - 10 years or more. While it’s true that EV batteries degrade over time, the rate of degradation is much slower than many people assume. When you know how to optimise your driving habits, charging and maintaining your battery you can extend its lifespan for many more years.

Yes, as you may have guessed, EV batteries are one of the most expensive components of an EV. A full battery replacement can still represent a significant expense, thousands or even tens of thousands €, particularly outside of warranty coverage. Some manufacturers offer battery refurbishment or module replacement options, which can be a more cost-effective solution compared to replacing the entire battery pack.

Repair costs for EV batteries are generally lower than replacement costs and can range from a few hundred to a few thousand €, depending on the issue.

Never replace or repair EV batteries yourself and always consult with a certified professional to diagnose the issue accurately, as some problems might be covered under warranty or might not require a full battery replacement.

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EV battery maintenance tips

Regular maintenance of your EV battery is crucial if you want to prolong its performance and reliability.

Visual inspections

Check the battery pack for any signs of damage, corrosion, or loose connections.

Software updates

Update the software regularly to have the latest release installed. Manufacturers release updates that can improve battery management system functionality, optimise charging algorithms, and enhance overall battery performance and longevity.

Professional inspections

A certified technician can assess the battery system, perform diagnostics, and identify issues that may not be apparent to the average owner.

Built-in battery health information

Many EVs provide access to battery health information through the vehicle’s dashboard or a connected app. You can easily check and monitor data on the battery’s health, capacity, range, and any diagnostic codes.

Smart charging

Use smart charging to schedule charging sessions during off-peak hours or when temperatures are cooler. This not only benefits the battery but can also take advantage of lower electricity rates. Many electric vehicle manufacturers have started integrating smart charging capabilities into their models, either directly or through compatible charging equipment and mobile apps.

The pivotal role of EV batteries in shaping the future of transportation is becoming increasingly clear. From powering our drives with cleaner, renewable energy to pushing the boundaries of range and efficiency, these technological marvels stand at the heart of the electric vehicle revolution. As the cost of EV batteries continues to decline and charging infrastructure expands, the barriers to EV adoption are rapidly diminishing.