“We see differences across vehicles and models,” Argue continues. There are other factors as well. “So far we haven’t seen a significant impact of high mileage on degradation rates, so you shouldn’t be afraid to use an electric vehicle.” This finding is consistent with the P3 study.
“However, we have observed a correlation with the frequency of DC fast charging,” warns Argue. “In cars that are frequently fast-charged, a noticeable increase in degradation rate has been observed.”
Balmy weather is also a factor affecting durability. “The worst-case scenario was three times that for a particular model used in hot climates and using frequent fast charging,” says Argue. This would mean a loss of 5.4 percent of battery capacity per year. However, “in the best cases, degradation averaged 1 percent per year. This is definitely a positive trend we are seeing.”
“When the electric vehicle market was emerging, there was great concern about factors that could lead to increased battery degradation,” says Neil Cawse, CEO of Geotab. “For example, full discharge, charging in cold and warm weather, using fast charging versus slow charging. However, battery technology has improved significantly, particularly with management systems – for example, ensuring that lithium-ion cells are properly charged when cold.”
Better battery performance can provide a longer warranty with greater remaining capacity. Toyota already offers a 10-year warranty on electric vehicle batteries, and MG is experimenting with it lifetime warranty in Thailand. “You still generally have a warranty of 70% health after eight years, but the degradation we see with these batteries is much less,” Wallace says.
Your electric vehicle can still be functional even after 20 years
However, previous research has relied on how car systems report battery health. “I would take all of these values with a grain of salt,” Wallace says. “The reported health status on the dashboard that a customer sees is often significantly different from what they see actual health condition results from this battery.” According to the report published by Elizja in 2023, the actual health status may differ by up to 9%. from the administered one.
Another issue is the buffer that manufacturers leave in their batteries, i.e. the difference between net and gross capacity in kWh. “OEMs are oversizing these batteries,” Wallace says. However, Argue explains that “there has to be some sort of safety buffer because we know from battery science that if a battery stays fully charged or completely empty for a long time, it causes more stress. Having a buffer protects the battery from degradation.”
Wallace believes this buffer is too conservative given the low degradation seen with EV batteries. “They don’t need that much excess capacity,” he says. “Smaller buffers mean smaller batteries, which lowers the cost of electric vehicles.” The problem is that Wallace believes that many time-honored automakers don’t yet have the necessary data about their batteries to take this step.
However, if batteries continue to function, as P3 and Geotab’s research suggests, electric vehicles could be in better shape than combustion engine vehicles of the same mileage and age. The rest of the electric vehicle is also cheaper to run. “Maintenance costs are much lower,” says Cawse. “You maintain the brake pads and replace the wipers – and that’s it.”
A 10-year-old EV may be almost as good as recent, and a 20-year-old still very useful. It could mean another disruption to the automotive industry, which after 15 years relies on cars that mostly end up in scrapyards.