Battery degradation is certainly a very valid question to ask. This isn’t leasing or renting, I got a loan at the bank, and purchased the car. So yeah, battery degradation is an issue, however to me battery degradation basically means that I would just have to charge more often.

All current figures I can find mention degradation between 0.5% and 3% per year. Taking the worst case of 3% and compounding it over 10 years, means my 77,4 kWh battery turns into a 57 kWh battery, that is a total of 73% of the original capacity, at 20 years this reduces to 54% of original capacity. At present I only use around 20-40% of my battery on an average day, which would mean that I would still be able to fulfill my daily driving needs. In the best case of 0.5% degradation, the total capacity would only have decreased to 73,6 kWh, 95% of the original capacity, or 90% after 20 years. The warranty on the battery ensures that the battery can’t lose more than 30% of its original capacity in the first 10 years, so it seems reasonable to think that Hyundai isn’t expecting the degradation to exceed 3%, and they likely have built in a good bit of margin into that warranty, as they obviously don’t want you to replace your battery free of charge.

It’s very important to understand what causes most of the battery degradation, though.

The main killer of batteries is heat. If the thermals of your battery isn’t managed well by the car your battery will degrade much much faster. This is why laptops and cellphone batteries don’t last very long. Most modern EVs has liquid cooling loops that keep the battery at the correct temperatures, both when driving and when charging. Many of the early EVs didn’t have this, and suffered for it. So many of the statistics about battery degradation are from the earlier EVs which didn’t manage temperatures well.

Charging to 100% wears the battery much more than charging to 80%, which in turn also wears more than charging to 70%. Depleting the battery and then charging to 80% again and again wears your battery more than staying between 40%-70%. Even better if you can keep your battery at a lower state of charge constantly, but that obviously means you have less range at your disposal. Charging faster also causes more wear. So with the right behaviour you can reduce your battery wear quite significantly. I have set my car up to only charge to 70% for normal days, and only increase the limit when I know I’m going on a long trip. I also almost exclusively charge at home, which means a nice and slow charge rate during the night when the outdoor temperatures are low. I only use more than 40% of the capacity between charges on very rare occasions.

My Ford Fiesta was 8 years when I sold it, and at 10 years it’s timing belt should be changed. Something that would cost about 1/3 of the market value of the car… And if the belt decides to give up before then, then I would have been looking at rebuilding the whole engine, which could easily be as expensive as the whole market value of the car. Besides that, there’s all the other bits in a combustion vehicle that needs maintenance, such as spark plugs, oil changes, transmissions, clutches, cylinder head gaskets, exhausts wearing trough. Even brake pads last longer as most of the braking is done by regenerative braking. EVs does however need the battery coolant changed, and does wear the tires quicker.

In the end battery degradation is a gamble that I have chosen to take. I personally think the benefits outweigh the risks, and even at 54% capacity after 20 years, the car would still be useful to me. I do however understand that this doesn’t work for everyone, and many others won’t be willing to take the same risk.

As a small follow up, new research seems to suggest that current EV batteries might last 40% longer than any predictions have expected, due to the real-world use of them causing very different wear on them than the heavy duty testing in labiratories:

https://lemm.ee/post/49902192