New study of 1,300 EVs busts battery degradation myths, Kia and Tesla top the list

We are getting some critical new data on battery health from a large-scale study in Sweden, and it’s a massive blow to EV naysayers.

The Swedish used-car marketplace Kvdbil conducted a large-scale test analyzing the “State of Health” (SoH) of over 1,300 used electric cars and plug-in hybrids (723 of which were all-electric).

The main takeaway? The persistent myth about rapid battery degradation is just that — a myth.

The study found that an impressive 8 out of 10 of the used EVs tested retained over 90% of their original battery capacity.

Unfortunately, they didn’t share the average mileage required to retain this capacity, as they virtually tested all used EVs that came through. Nonetheless, this is a fantastic result that should give used EV buyers a ton of confidence.

Martin Reinholdsson, test manager at Kvdbil, commented on the findings:

“The degradation of a car battery occurs slowly thanks to advanced technology and smart design, including cooling of the battery cells. This result also disproves the myth that used cars’ batteries wouldn’t last long.”

When looking at the top-performing all-electric models, the list is very interesting. Kia impressively took the top two spots with the EV6 and the Niro Electric, which have consistently shown strong battery performance.

Right behind them, the Tesla Model Y secured a strong third-place finish. Considering the Model Y is the highest-volume vehicle in the bunch, that’s good news.

Here is the full top 10 list of EVs with the best average battery health:

1. Kia EV6
2. Kia e-Niro
3. Tesla Model Y
4. Opel Mokka-e
5. Mazda MX-30
6. Audi Q4 e-tron
7. Fiat 500e
8. Volvo XC40 Recharge
9. Citroën e-C4
10. Volkswagen ID.4

Tesla. When ranking brands overall (including all their EV models), Tesla ranked fourth, just behind Kia, Audi, and Opel.

However, I’m concerned that this might be due to the average age/mileage of Tesla vehicles compared to those of these other brands. The data needs to be normalized for mileage.

The study also confirmed what most EV owners already know: the best way to maintain battery health is to follow good charging habits, such as limiting daily charging to 80% and minimizing the use of DC fast-charging.

Electrek’s Take

For years, a major talking point against EV adoption has been the unsubstantiated fear that the battery pack will be useless after 5-8 years, resulting in a five-figure replacement cost.

Battery replacements indeed remain expensive, but the myth that they would be needed is getting busted.

It is starting to look like batteries will outlast the vehicles themselves.

Modern, liquid-cooled battery packs are incredibly robust. Seeing 80% of all EVs tested retain over 90% of their capacity should help build confidence in the nascent used EV market.