Does frequently fast charging your EV damage its battery?

Welcome to The Switch, Euronews Next’s new mobility series for people considering making the switch to an EV.

As the pace of electrification quickens amid a growing climate crisis and an uncertain economic outlook, we’ll be your companion as you make the transition from your fossil-fuelled car to electric. 

Each week, we’ll offer guidance and insights from industry experts as well as aim to demystify the process and dispel misinformation.

For many, electric vehicles (EVs) represent the future of transportation and a means to reduce emissions, but they have also heralded a new lexicon of maintenance concerns. 

Chief among these considerations is whether frequent use of direct current (DC) fast charging impacts the lifespan of EV batteries. 

While early industry wisdom suggested that regular fast charging might degrade battery capacity over time, recent research is challenging this assumption, particularly for models equipped with advanced battery management systems.

New findings on fast charging’s impact

In a recent study, Recurrent researchers analysed data from over 13,000 EVs to assess the effects of frequent fast charging. 

Contrary to laboratory predictions, data from over 160,000 real-world charging events revealed no significant difference in battery range degradation between Teslas that fast-charge frequently and those that do so sparingly. 

However, the study primarily includes data from newer vehicles (2018 onwards, with most from 2021 or later), covering only about five to six years of usage. Therefore, long-term effects of fast charging remain uncertain. 

All lithium-ion batteries experience gradual range loss over time, and Tesla’s batteries – fast-charged or not – show expected range degradation regardless of charging habits. Real-world range loss may vary due to factors like terrain and weather.

How modern EVs combat battery degradation

The sophistication of battery and thermal management systems in EVs has evolved to a point where many vehicles can handle fast charging without significant degradation. Several factors contribute to this resilience.

Firstly, advanced battery management system (BMS) technology monitors and adjusts each cell’s voltage, current, and temperature in real-time. 

Through this constant observation, the BMS ensures these parameters stay within safe limits, preventing overheating and overcharging. If temperatures rise too high, the BMS slows down charging or activates the cooling system to protect battery health.

Heat is a battery’s enemy, especially during high-speed charging. Modern EVs use thermal management systems (TMS) – liquid cooling or even air conditioning – to keep battery cells at a stable temperature, reducing the strain fast charging can place on the battery. 

Liquid cooling systems, for example, allow cells to remain at a safe temperature even during extended fast-charging sessions. 

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Working alongside BMSs, TMSs enforce current limits and mitigate risks like thermal runaway, extending battery life, and making fast charging both safer and more efficient.

Battery chemistry is also highly influential. Different battery chemistries exhibit varying degrees of resilience under fast charging conditions. 

Lithium Iron Phosphate (LFP) batteries, increasingly adopted by Tesla and others, are particularly robust under high charging rates. 

Nickel Manganese Cobalt (NMC) batteries, by contrast, are more prone to wear, especially in high-heat conditions. However, carmakers are making strides with both chemistries, employing a BMS to offset some of the stress from fast charging. 

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Ultimately, selecting the right chemistry involves balancing fast-charging capability, durability, and energy density. The focus is on developing batteries that can handle higher power inputs without degrading quickly, while also being cost-effective and environmentally friendly.

When fast charging can stress EV batteries

While fast charging is generally safe for most EVs, some conditions may still pose risks to battery longevity.

Charging in extreme temperatures – either very hot or very cold conditions – can increase battery stress, particularly if the battery isn’t preconditioned. Data from Geotab shows that fast charging in hot conditions can accelerate battery degradation.

Batteries face more resistance when charged from very low or nearly full states, which can contribute to degradation so avoid fast charging when your car battery is extremely hot, freezing cold, or at a high or low state of charge. 

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For this reason, many manufacturers recommend avoiding fast charging when the battery is almost empty or close to 100 per cent.

High-mileage usage is also a consideration. Vehicles undergoing fast charging multiple times daily over high mileage may experience slightly more wear, although the impact is usually minimal if the BMS is functioning well.

Consistently fast-charging to 100 per cent puts more strain on the battery than stopping at 80 per cent, as the final charging stage tends to heat the cells more. To maximise battery lifespan, many manufacturers suggest limiting fast charging to around 80 per cent.

Preconditioning the battery – heating or cooling it to an optimal temperature before charging – enables a gentler charging process. Fast charging without preconditioning, particularly in extreme temperatures, can be more harmful.

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Top tips for minimising battery degradation

On balance, to further protect EV batteries during fast charging, you should try the following:

• Precondition the battery in extreme weather before charging.

• Avoid regularly charging to 100 per cent; aim for 80 per cent instead.

• Balance fast charging with slower Level 2 charging when possible.

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• Follow manufacturer recommendations for optimal charging practices.

The future of fast charging

Recent studies suggest that frequent fast charging may not significantly degrade EV batteries, challenging prior assumptions. 

Today’s EVs are equipped with advanced BMS, improved thermal management, and resilient chemistries like LFP to combat degradation. 

Ultra-fast chargers, soon exceeding 350 kW, could cut charging times dramatically, reaching 80 per cent in as little as 15 minutes. 

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With ongoing advances in lithium-ion, solid-state, and lithium-sulfur batteries, alongside smart charging infrastructure, EVs are poised to become faster, safer, and more reliable to charge.

Geraldine Herbertis the motoring editor for the Sunday Independent newspaper and an e-mobility expert.