Fred Lambert, writing for Electrek:

Battery degradation is one of the biggest concerns for electric car owners and potential buyers, but data from Tesla battery packs have been very reassuring so far.

Now the latest data shows less than 10% degradation of the energy capacity after over 160,000 miles on Tesla’s battery packs […]

The data clearly shows that for the first 50,000 miles (100,000 km), most Tesla battery packs will lose about 5% of their capacity, but after the 50,000-mile mark, the capacity levels off and it looks like it could be difficult to make a pack degrade by another 5%.

The trend line currently suggests that the average battery pack could cycle through over 300,000 km (186,000) before coming close to 90% capacity […]

Meanwhile, Nissan has issues with the Leaf:

A recent study shows that with the original 24 kWh pack loses about 20% of their capacity over 5 years and Nissan’s more recent 30 kWh battery pack loses capacity more quickly than the older pack […]

The next few years will be interesting for car buyers. We haven’t had to worry about engines as much so far — they’re more or less reliable enough and don’t lose much power over the years — but battery packs directly influence the usability of an electric car. I privately wanted a Leaf as a city car, but if its pack degrades as quickly as the study above shows, then I will have to reconsider it as an option.