- Health of batteries in latest EV models degrades on average by 1.8% per year
One of the biggest concerns about switching to electric cars is the longevity of their batteries, with some even fearing they could need to be replaced at a high cost.
But a new report has attempted to quash these fears by stating batteries in new EVs are good for 20 years or longer.
In fact, the investigation based on 5,000 real-life modern EVs says batteries show slower signs of degradation than components used in internal combustion engine (ICE) cars.
A new report claims that batteries in the latest EVs generally outlast components used in internal combustion engines. As such, an electric car’s battery should be good for 20 years or more
The bold claims are made by Geotab – a leading firm in fleet and business telematics, which involves tracking vehicles and connecting them to the internet.
The company says it has carried out analysis of the battery health of almost 5,000 fleet and private EVs, using 1.5 million days of telematics data to explore how the latest battery technology holds up to the rigours of daily use.
The data suggested that EV batteries in current models degrade, on average, by 1.8 per cent annually.
When it carried out the same study back in 2019, it found that the efficiency of batteries was declining at a rate of 2.3 per cent per year on average, suggesting advances have been made in the last five years to extend the lifespan of the technology.
The report went on to say that EV batteries now ‘generally degrade more slowly than internal combustion engine drivetrain components’.
David Savage, vice president for the UK and Ireland at Geotab, added: ‘With these higher levels of sustained health, batteries in the latest EV models will comfortably outlast the usable life of the vehicle and will likely not need to be replaced.
‘However, we still see battery reliability being used as a stick to beat EVs with.
‘Hopefully, data like ours can finally put these myths to bed.’
The report says an average 1.8 per cent decline in battery health is ‘unlikely to have a significant impact on most driver’s daily vehicle needs’.
It adds that this degradation should decline in the future with the arrival of new EV models and further advances in batteries, such as solid-state battery tech.
‘People should feel confident that many current EVs are suitable and cost-effective to replace a range of light, medium and heavy-duty ICE vehicles,’ David went on.
One of the biggest concerns restricting the drivers switching to electric cars is the longevity of their batteries and how often they could need to be replaced at a high cost
How the EV battery analysis was done
Geotab calculates degradation by using telematics data gathered during charging.
It takes the kWh added during a charging session and divides that value by the change in the State of Charge increase for every qualified charge event.
This calculation, taken over recent charges, provides an estimate of the current battery capacity, which creates a ratio when divided by the vehicle’s starting battery capacity (battery capacity for that make/model as new).
It then takes the weekly or monthly mean for each vehicle to create a data point over time.
Geotab uses curve fitting by make-model-year for all weekly mean points for each vehicle model.
The data is based on 21 different EV models with best-performing posting annual battery degradation at a rate of just 1 per cent.
Potential contributors to why batteries in some vehicle models, on average, degrade faster than others are battery chemistry and thermal management of the battery pack.
‘While current EVs mostly use lithium-ion batteries, there are many different variations of lithium-ion chemistries and this will influence how it responds to stress,’ Geotab’s report said.
‘In addition to cell chemistry, temperature control techniques differ across vehicle models.’
Another major distinction is whether the battery pack is cooled and/or heated by air or liquid.
One surprising finding from the research is that high-mileage EVs did not show significantly accelerated battery degradation than others.
‘This should be welcome news to fleet operators in particular since EVs offer better value the more they are driven,’ the report added.
Geotab’s report suggested that EV batteries in current models degrade, on average, by 1.8% annually
What is battery degradation – and should it stop you switching to an EV?
Battery degradation is a natural process that permanently reduces the amount of energy a battery can store or the amount of power it can deliver.
The batteries in EVs can generally deliver more power than the powertrain components can handle.
As a result, power degradation is rarely observable in EVs and only the loss of the battery’s ability to store energy matters.
An EV battery’s condition is called its state of health (SOH).
Batteries start their life with 100 per cent SOH and over time they deteriorate.
For example, a 60kWh battery with 90 per cent SOH would effectively perform like a 54kWh battery.