The current go-to technology for EV battery packs is batteries based on lithium ion (Li-ion) chemistries. Li-ion batteries offer a lot of advantages including cost and energy density but one downside they have is, over time, their ability to hold a charge degrades.
While this is an inescapable characteristic of Li-ion batteries, there are things manufacturers can to do slow the rate of degradation. Tesla has invested significant R&D on managing pack degradation and employs multiple strategies to ensure your battery pack is coddled. While much of this happens begin the scenes, some visible examples include how the rate of charge tapers during Supercharging, how the heat or AC will automatically kick on to ensure your pack stays in its ideal operating temperature range and the 8-year unlimited mile battery warranty.
Typically, owners see a drop of a few miles of rated range at around the one year mark, which can seem a bit disconcerting, but degradation is not linear. After the first big drop, pack capacity reduction seems to follow a much more gentle trajectory. This chart is from data collected by a Tesla owners group in Europe. As you can see there is a quick drop then a shallow taper. Their data suggest a drop of about 1% of capacity every 30,000 miles.
My own experience is I have lost ~6% of capacity after ~100,000 miles on my P85. To be honest, I really don’t miss those miles. If you are interested in a bit more information on pack longevity, check out this post in the “EV Myths” section.
There are a few things you, as an owner, can do to improve pack health and slow degradation:
You will find there is no shortage of urban legends around coaxing the most out of your pack. My advice is to relax, enjoy your car and trust Elon and his engineers to do their jobs. If you ever have questions about the health of your battery pack, call Service and they can remotely take a look at your car and see if there is any case for concern.