When I mention buying an electric vehicle to people, one of their first questions is: “how long will the battery last?”  Followed by: “how much does it cost to replace it?”

It’s a tough series of questions because of the unknowns and the potential downside.  Generally we can say that most automakers will insure the battery for 8-10 years, while battery costs are coming down.

But when you tell people a new battery can cost tens of thousands dollars and that ‘we really don’t know’ how long they’ll last, it can be a quick turn-off for potential buyers (and may explain the popularity of EV leases).

EVs have now been on the road in sizeable numbers for about five years though, so we’re starting to get some good data.  And as Electrek reports, the news is pretty good, at least for Tesla batteries:

Data shows that the Model S’ battery pack generally only loses about 5% of its capacity within the first 50,000 miles and then the degradation significantly slows down with higher mileage. Plug-in America’s data shows several vehicles with over 100,000 miles driven and less than 8% degradation.

And anecdotally:

CEO Elon Musk once referred to a battery pack Tesla was testing in the lab. He said that the company had simulated over 500,000 miles on it and that it was still operating at over 80% of its original capacity.

This is all encouraging to hear, as that kind of degradation is relatively minor. And as noted, prices are coming down on batteries.  It’s unclear if Tesla’s success though will translate to other EVs, as each company is using different chemistries and technologies.  But the news on at least newer Nissans, for example, looks promising, too.

For some people it will take a lot more data like these to reassure them.  So it’s nice to get some early returns and to see that the initial reports are generally positive.  Otherwise, time will tell.