Whilst the driving satisfaction of EVs has long been accepted, concerns over batteries has remained.

In addition to problems of range and charging, the length of their usable life has also been an area of discussion and negative opinion.

How many times can an EV battery be charged before it becomes unviable for practical motoring?

The power drain

With a degradation rate of just 1.8% per year, a new study suggests that the vast majority of electric vehicle (EV) batteries will outlast the usable life of the vehicle.

The data published by Geotab indicates EV batteries will now last 20 years or more.

The company analysed the battery health of almost 5,000 fleet and private EVs.

It represents nearly 1.5 million days of telematics data, and it explores how the latest battery technology holds up to the rigours of daily use.

This data highlights how batteries degrade, on average, by 1.8% per year – compared to 2.3% when Geotab last performed a wholesale analysis of EV battery health in 2019.

Compared to internal combustion engine (ICE) drivetrain components, this rate of decline is a lot more favourable.

Reliable future

David Savage, vice president for the UK and Ireland at Geotab, explained: “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, he said: “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 fact is that a 1.8% decline in battery health is unlikely to have a significant impact on most driver’s daily vehicle needs, and this number will only come down further with new EV models and improved battery technology.

“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.”

In charge

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% SOH and deteriorate over time.

For example, a 60kWh battery with 90% SOH would effectively act like a 54kWh battery.

Charging on

The best-performing EV models in the updated Geotab analysis posted a battery degradation rate of just 1%.

Potential reasons for degradation variability include 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 they respond to stress.

In addition to cell chemistry, temperature control techniques differ across vehicle models. A significant distinction is whether the battery pack is cooled and/or heated by air or liquid.

Another potentially surprising insight from the Geotab research is that high-use EVs did not show significantly higher battery degradation than others.

This should be welcome news to fleet operators, particularly since EVs offer better value the more they are driven.