MG and Geotab give insights into what determines EV battery life

As electric vehicles (EVs) grow in popularity, drivers and fleet managers alike are increasingly concerned with one crucial question: how long will an EV’s battery last? While EVs offer several benefits, such as reduced emissions and lower fuel costs, the longevity of their batteries remains a key consideration. Reports from MG, an automaker with a growing range of EVs, and Geotab, a telematics company specialising in data collection for the transport sector, provide valuable insights into what determines an EV battery's life and how drivers can extend it.

Understanding EV Battery Lifespan

There is no one-size-fits-all answer to the question of EV battery life. Battery longevity is influenced by a wide range of factors, from the frequency of charging cycles to the specific make and model of the vehicle. These variables make it difficult to offer definitive guidance on how long a battery will last. However, there is a growing body of research and real-world data that provides useful insights.

According to Geotab, which has analysed data from over 6,000 electric vehicles, EV batteries degrade at an average rate of 2.3% per year. This means that after five years, an EV batteries will typically lost about 11.5% of their capacity. For a vehicle with a range of 150 miles, this would translate into a loss of approximately 17 miles of accessible range. Although this decline may seem significant, it is unlikely to have a major impact on most drivers' daily needs. In fact, in many cases, the battery will last longer than the vehicle itself.

Factors Affecting Battery Life

Several factors can influence the lifespan of an EV battery. Both MG and Geotab highlight the importance of careful management of the battery’s state of charge, the environment in which the vehicle operates, and the frequency and type of charging.

1. Charging Cycles: One of the key determinants of battery life is the number of charging cycles it undergoes. A charging cycle refers to a complete discharge and recharge of the battery. The more cycles a battery goes through, the more its capacity will degrade over time. However, it’s important to note that battery degradation is not necessarily tied to the age of the vehicle. A 10-year-old EV that has been driven sparingly may have a battery in better condition than a five-year-old vehicle that has seen heavy use.
2. Battery Management Systems: Many EV manufacturers, including MG, implement measures to extend the life of the battery. For example, MG’s come with a buffered battery, meaning the vehicle’s software restricts access to the full capacity of the battery. This prevents the battery from undergoing unnecessary cycles, which helps reduce degradation. Additionally, MG vehicles feature systems to prevent “bricking”—a situation where the battery becomes so depleted that it can no longer be charged.
3. Temperature Control: The performance of an EV battery is closely linked to temperature. Batteries operate most efficiently in temperatures between 15 and 25 degrees Celsius. When exposed to extreme heat or cold, the battery's ability to hold a charge diminishes. MG addresses this issue by including temperature management systems in its vehicles. For instance, MG can use a heat pump to regulate the battery’s temperature, helping to maintain optimal performance regardless of external conditions. Geotab’s research also indicates that vehicles driven in hotter climates show higher rates of battery degradation, making temperature control an essential factor in prolonging battery life.
4. Charging Methods: There has been some debate over whether fast charging (also known as DC charging) is harmful to EV batteries. According to MG, repeated fast charging does not significantly degrade battery health because the vehicle's system monitors the battery during charging and adjusts the speed if necessary to prevent overheating. However, Geotab’s data reveals that while the occasional use of DC fast chargers is unlikely to cause significant harm, frequent use—especially in hot climates—can accelerate degradation. For this reason, both MG and Geotab recommend prioritising Level 2 (AC) charging for everyday use.
5. State of Charge: Keeping the battery at an ideal state of charge is another way to prolong its lifespan. Both MG and Geotab suggest maintaining the battery between 20% and 80% charge whenever possible. This reduces stress on the battery and helps prevent degradation. For instance, manufacturers can allow drivers to set a target charge level, so the battery does not exceed a certain percentage. This flexibility gives drivers more control over their battery’s health.

Real-World Battery Performance

Geotab’s analysis of 6,300 fleet and consumer EVs offers a detailed view of how batteries perform in real-world conditions. Their data suggests that while all batteries degrade over time, the rate of degradation varies significantly between different makes and models. For example, vehicles with better thermal management systems, such as those used by Tesla, exhibit lower degradation rates compared to those with less sophisticated cooling systems, like the Nissan Leaf. Set a Supercharger destination into a Tesla's satnav and it will immediately start to condition the battery for optimum charging.

One of the key findings from Geotab’s research is that EVs used intensively do not necessarily experience faster battery degradation. In fact, the data shows that vehicles used frequently and for long periods maintain similar degradation rates to those used less often. The main caveat is that high-use vehicles relying on frequent DC fast charging may degrade faster, particularly in hot climates.

How Long Will EV Batteries Last?

According to Geotab, if current degradation rates hold steady, the majority of EV batteries will outlast the useful life of the vehicle. On average, an EV battery would take 15 years to degrade to 70% of its original capacity. This is a promising figure, considering that many EVs on the road today are only a few years old. However, it’s important to remember that battery degradation is not entirely linear. While the initial drop in capacity may be noticeable, it typically slows down after the first few years, only to experience a more significant decline towards the end of the battery’s life.

Both MG and Geotab emphasise the importance of manufacturer warranties as a safeguard for consumers. Most automakers offer warranties of around eight years or 100,000 miles for EV batteries, providing peace of mind to drivers concerned about the longevity of their battery. After gaining many years of information about degradation, MG is now looking at ‘lifetime' warranties for its EV batteries. Others will surely follow.

Best Practices for Maximising EV Battery Life

While EV batteries are built to last, drivers can take several steps to extend their battery’s lifespan. Following best practices can help ensure that the battery performs well throughout the vehicle’s life cycle.

Checklist: How to Extend the Life of Your EV Battery

• Maintain a State of Charge between 20-80%: Avoid letting the battery discharge completely or charge to 100%, as this can accelerate degradation.
• Use DC Fast Charging Sparingly: Fast charging can generate excess heat, which stresses the battery. Prioritise Level 2 charging whenever possible, especially in hot climates.
• Manage Extreme Temperatures: Park in the shade on hot days and consider using climate control systems to keep the battery within its optimal temperature range.
• Avoid Prolonged Storage with a Low Charge: If you plan to leave your EV unused for an extended period, ensure the battery is at least 50% charged to prevent it from becoming too depleted.
• Use Manufacturer-Provided Battery Management Tools: Many modern EVs allow you to set a maximum charge level or control when the battery charges. Utilise these tools to maintain the battery's health.
• Monitor Battery Health Regularly: If your EV comes with battery health monitoring features, check them periodically to stay informed about the state of your battery.

Conclusion

The life of an EV battery is influenced by many factors, but with proper management, most batteries will last well beyond the usable life of the vehicle. Advances in battery technology, combined with effective thermal management and charging practices, mean that drivers can confidently adopt electric vehicles without worrying about battery replacement costs. By following best practices, drivers can maximise their battery’s longevity and ensure that their EV continues to deliver optimal performance for years to come. One thing is for sure, with all of the new battery technologies coming to market, Nio's EV battery swap system is never likely to see the light of day, in the UK. MG came into this market with the ZS EV and a range of around 163 miles in 2019. Now you can get an affordable MG4 that will deliver double that range on a single charge. Things are moving quickly.