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How to check your Tesla's battery health: the built-in test, what the result means and how to slow degradation4 min

How to check your Tesla's battery health: the built-in test, what the result means and how to slow degradation

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Teslas can now measure their own battery health. A step-by-step guide to running the test, reading the percentage, and the charging habits Tesla recommends to keep your battery healthy.

Every lithium-ion battery slowly loses capacity, and a Tesla is no exception. The good news is that you no longer have to guess how much yours has lost: Teslas have a built-in battery health test. Here is how to run it, how to read the result, and what actually helps a battery last.

How much do Tesla batteries degrade?

Tesla's 2022 Impact Report said its Model S and Model X batteries had lost about 12% of their capacity on average after 200,000 miles (about 320,000 km). In other words, they kept around 88%. Tesla has published less data for the Model 3 and Model Y, which use several different cell types.

The battery warranty sets a floor: at least 70% capacity over 8 years, with a mileage limit of 100,000 to 150,000 miles (160,000 to 240,000 km) depending on the model.

How to run the battery health test

Tesla added the test to its software in 2025. According to Not a Tesla App, it works like this:

  • Find it: go to Controls, then Service, and scroll to Battery Health. The screen lists the requirements and your last result.
  • Start low: the battery should be at 20% or less.
  • Plug in at home: use a Wall Connector or Mobile Connector that delivers at least 5 kW.
  • Check the basics: the car must be in Park, online, with no software update scheduled and no battery or thermal alerts.
  • Be patient: the car drains the battery almost empty by running its motors and heating system, then charges it fully. This can take up to 18 hours, and the fans can be loud.

When it is done, the Tesla app sends a notification and shows the result under Service, Battery Health. The test can be run once every six months.

How to read the result

The result is shown as a percentage of the original capacity. Not a Tesla App reports that most cars land between 10% and 20% degradation, so a reading in the 80s is normal for a car that is a few years old. If a car under warranty shows 70% or less, contact Tesla service.

Two side effects are worth knowing. Your displayed range may change after the test, because the battery management system recalibrates; the real range does not change. And the car ends the test at 100%, so drive it soon afterwards if it has a battery that should not sit full for long.

Habits that help a battery last

Tesla's owner's manual gives simple advice:

  • Daily limit: if your car recommends a daily limit of 80%, keep it around there and charge to 100% only before long trips.
  • LFP batteries are different: Tesla advises keeping the limit at 100% even for daily use and fully charging at least once a week. You can tell you have one if the charge screen shows "50%" and "100%" instead of "Daily" and "Trip".
  • Avoid the extremes: do not leave the battery near 0% or 100% for long, and never let it run completely flat. Damage from a full discharge is not covered by the warranty.
  • Stay plugged in: the battery works best when charged regularly. For long parking, Tesla suggests about 50% and leaving the car plugged in.
  • Supercharging is fine: the manual says frequent fast charging can slightly reduce peak charging speed over time, but it does not tell owners to avoid it.

Buying a used Tesla? Ask for the test

For a used car, battery health is the one number that tells you most about future range. Ask the seller to run the test before you buy, or to show a recent result in the app. Compare it with the car's age and mileage, and check how much battery warranty is left. A car with 85% after five years and 100,000 km is doing well; a much lower figure on a young car is worth questioning.

What to keep in mind

The test is a snapshot. Results can vary a little between runs, and a single reading a few points lower than expected is no reason to panic. What matters is the trend over time, and whether the car still has the range you need.

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