One thing prospective EV buyers are concerned about, is battery range.
While electric vehicles do offer a multitude of measures to slow down the process of battery degradation, it is inevitable. EVs are proven to have considerably lower ownership costs than petrol cars, but battery longevity it still something that causes concern.
How long a battery will last is a question not only asked by consumers, but the manufacturers too. Atlis Motor Vehicles CEO, Mark Hanchett, says “every single battery is going to degrade every time you charge and discharge it.”
Essentially, any rechargeable lithium-ion (Li-ion) battery will lose capacity over time. But the rate at which this process happens is the unknown variable. There are lots of factors that’ll affect your batteries long-term energy storage, from your charging habits to the chemical makeup of the cell.
And while there are many contributors to the equation, there are four main elements to consider.
Fast charging in itself doesn’t necessarily aid in the accelerated degradation of the battery, but an increased thermal load can damage the internal components of the battery cell.
This internal damage can lead to fewer Li-ions being transferred from the cathode to the anode. But the rate of this degradation isn’t as high as you’d think.
In 2014, the Idaho National Laboratory tested four 2012 Nissan Leafs, two charged on a 3.3 kW home charger and the other two strictly charged at 50 kW DC fast stations. After 40,000 miles (around 64,374 km), the car charged on just the DC had 3% more degradation. 3% will certainly affect your range, but the ambient temperature appeared to have a much more significant influence on the overall capacity.
Interestingly, colder temperatures have been shown to slow down an EV’s charge rate and temporarily limit its overall range. Warmer conditions tend to be more beneficial for rapid charging, but prolonged exposure to hot temperatures can cause damage to the cells.
Try to leave your EV plugged in if it’ll be sitting for extended periods of time through summer. If possible, park in the shade (especially if you have an EV that doesn’t have a liquid-cooled battery).
Like any rechargeable Li-ion battery, the more charge cycles, the more wear on the cell. Tesla reported that after around 40,000 kms, the Model S will see around 5% degradation, with an additional 5% degradation after 201,200 km. Of course, there’ll be outlier that aren’t shown in the stats, but in general this is what’s to be expected.
Unlike mileage, time typically has the most significant affect on batteries. In 2016, Mark Larsen reported that his Nissan Leaf lost about 35% battery capacity after eight years. While this is a rather high percentage, we know that early Nissan Leaf cars suffer more severe degradation. Liquid-cooled battery options should see much lower percentages of degradation.
Today, the battery technology we have is far more advanced than it was a decade ago. So if you’re in the market for an EV, it’s better to spend more on a newer EV than to pay for an out-of-warranty batter repair on an older car.