How to Check Your Tesla's Battery Degradation Using the Built-in Battery Health Test

One of the most common concerns for EV owners is battery degradation. How much range will you lose over time? Is your battery healthy? With software update 2025.8.3, Tesla introduced a built-in Battery Health Test that gives you a definitive answer.

In this guide, I'll show you exactly how to run the test, the prerequisites you need to meet, what the results mean, and share my own real-world results after 5.5 years and 95,000 km of ownership.

What is the Tesla Battery Health Test?

The Battery Health Test is a diagnostic feature that measures your battery's current energy retention compared to when it was new. It gives you a percentage that represents how much of your original battery capacity remains.

For example, if your test shows 89%, it means your battery can hold 89% of its original capacity. If your car originally had 500 km of range, you'd now have approximately 445 km at full charge.

You can view an initial evaluation anytime by going to Controls > Service > Battery Health. But for a more accurate measurement, you'll want to run the full Battery Health Test.

Prerequisites for Running the Test

The Battery Health Test has strict requirements. All of these must be met before you can start:

• Software version 2025.8.3 or later
• Plugged into an AC charger (at least 5 kW)
• At least 14-18 hours of plugged-in time without any interaction with the car
• Vehicle must be in Park
• No active alerts or pending software updates
• Less than 20% battery remaining
• Connected to Wi-Fi or cellular

If any of these conditions aren't met, your car will show an alert explaining what's missing.

How to Run the Battery Health Test

Once you meet all the prerequisites, here's how to run the test:

Step 1: Navigate to Battery Health Test

On your Tesla's touchscreen, go to Controls > Service > Battery Health Test.

Step 2: Start the Test

Read the popup information, then tap Start Test. The test requires a Wi-Fi or cellular connection to begin.

Step 3: Wait for Completion

This is the important part — the test can take up to 24 hours to complete. During the test:

• The touchscreen will show progress
• The battery may discharge below 10%
• Climate control will be disabled — do not leave occupants unattended in the vehicle

Step 4: Don't Interact with the Vehicle

This is crucial: don't interact with the vehicle or the Tesla app during the test. If you need to cancel, do so via the touchscreen or app — but don't unplug the car without canceling first.

Step 5: View Your Results

Once complete, the touchscreen displays your battery's energy retention percentage compared to when it was new. Your range estimate may also be recalibrated based on the results.

Which Tesla Models Support the Battery Health Test?

• Model 3 & Model Y: Available with software 2025.8.3 or later
• Model S & Model X: Available on 2021+ models with matrix headlights and software 2025.8.3. Older models may not support it.
• Cybertruck: Not currently available in the main user interface

Why You Might Not Be Able to Run the Test

If the Battery Health Test isn't available or won't start, here are common reasons:

• Software version: Pre-2025.8.3 software doesn't have this feature
• Hardware limitations: Some older models or variants may lack compatible hardware
• Post-test lockout: After running the test, it's unavailable until the battery management system detects a significant change
• Connectivity: The option won't appear without Wi-Fi or cellular connection
• Prerequisites not met: Vehicle not plugged in, battery above 20%, or other conditions not satisfied

Understanding Your Results

What's a "good" battery health percentage? Here's a general guide:

• 95-100%: Excellent — Typical for cars under 2 years old or with low mileage
• 90-95%: Very Good — Normal for cars 2-4 years old
• 85-90%: Good — Expected for cars 4-6 years old or with higher mileage
• 80-85%: Fair — Getting older but still functional
• Below 80%: Consider service — May be eligible for warranty replacement if under 8 years/192,000 km

Tesla's battery warranty covers degradation below 70% capacity within 8 years or 192,000 km (whichever comes first) for Model 3 and Model Y.

If energy retention impacts your usability, you can schedule a service appointment directly through the Tesla app.

My Real-World Results: 5.5 Years and 95,000 km

I ran the Battery Health Test on my Tesla, and here are my results:

• Age: 5.5 years
• Odometer: 95,000 km
• Battery Health: 89%

I'm really happy with this result. An 11% degradation over 5.5 years and nearly 100,000 km is well within the expected range — and honestly better than I expected.

Based on various studies and real-world data, Tesla batteries typically degrade about 10-15% in the first 5 years, then the degradation curve flattens significantly. My 89% puts me right in that sweet spot.

Tips to Maximize Battery Longevity

Want to keep your battery healthy as long as possible? Here's what I do:

1. Keep the car plugged in when not in use — Tesla recommends this for battery health
2. Set daily charge limit to 80% — Only charge to 100% before long trips
3. Avoid frequent fast charging — Supercharging occasionally is fine, but daily use may increase wear
4. Pre-condition before Supercharging — Use navigation to warm up the battery
5. Park in shade during hot weather — Extreme heat is harder on batteries than cold

Quick Alternative: Battery Degradation Calculators

If you don't want to wait 18-24 hours for the official test, or if your car doesn't support it, there are online calculators that can give you a quick estimate based on your car's age and mileage.

These won't be as accurate as the official test, but they can give you a ballpark figure to see if you should be concerned.

Final Thoughts

The Battery Health Test is a welcome addition to Tesla's software. It gives owners transparency and peace of mind about their battery's condition — something we've wanted for years.

Yes, the prerequisites are strict (14-18 hours plugged in, under 20% charge), but it's worth the wait for accurate results. My 89% after 5.5 years and 95,000 km confirms what I've always believed: Tesla batteries are built to last.

If you haven't run the test yet, plan ahead — let your battery drop below 20%, plug in overnight (or longer), and run the test when you won't need the car for a day. The peace of mind is worth it.

Happy driving! ⚡🚗

Related: How to Create and Apply Custom Wraps to Your Tesla's Display