How Tesla's Regenerative Braking Works

Tesla offers three stopping modes

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Braking is essential to the driving experience, but not all systems are created equal. A regenerative braking system (RBS) is the most significant difference people notice the first time they operate an electric vehicle.

Regen, as commonly referred to, makes it possible to drive a Tesla and never touch the brake pedal (along with some brake blending for slow speeds), not only reducing wear and tear on braking components but putting energy back into the battery. There are some estimates that regenerative braking can add 10 percent more range and extend the life of braking mechanisms by more than 50 percent.

What is Tesla's Regenerative Braking?

Unlike traditional brakes, which rely on friction to stop the wheels from turning, regenerative braking uses the vehicle's electric motor to create resistance to slow down the vehicle. In addition to slowing the vehicle down without the use of brakes, the motor running in reverse acts as a generator and captures the kinetic energy that would typically be lost as heat and converts it into electrical energy, thereby increasing your vehicle's range.

How to Activate Regen in a Tesla

In a Tesla, the regenerative braking system is activated by lifting your foot off the accelerator. The more you ease off the accelerator, the stronger the braking force and the more energy is captured.

Tesla's Power Meter (Regen bar)

Tesla's power meter, also known as the regen bar or line

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All Teslas feature a power meter either in the instrument cluster (Model S and X) or the center screen (Model 3 and Y) that displays the amount of energy being captured through regenerative braking, or the amount of energy being used by accelerating the vehicle.

The center of the line is considered neutral. Anything to the left of the center point means energy is being captured, while anything to the right means that energy is being used.

The further the line grows to the left, the greater the amount of regenerative braking is taking place, and the more it moves to the right, the greater the amount of power is being used.

The regenerative braking line is green, while the power line is black (or white when in dark mode). You may occasionally also see a gray line on the left side. This will appear if the vehicle has the 'Apply Brakes When Regenerative Braking Is Limited' feature turned on. This feature introduces a consistent braking experience when lifting your foot off the accelerator pedal when regenerative braking is limited.

You may also see the gray line appear on the left side of the power meter if the vehicle is in Autopilot. This helps the driver understand when the vehicle is using regenerative braking or physical brakes to slow down.

How Does Regenerative Braking Work?

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Without getting too deep into Physics, kinetic energy is energy in motion. Therefore, anytime a car slows down, the kinetic energy that is produced has to go somewhere. With traditional brakes, that is heat from abrasion generated from the brake pads squeezing the rotors. But this energy can be used in a different way. In the words of a Tesla engineer, "kinetic energy stored in a moving vehicle is related to the mass and speed of the vehicle by the equation E = ½mv²."

You can see this equation play out every time you drive your Tesla by looking at the vehicle's power meter.

The motor controller manages the torque of the motor. This action helps with both driving and regenerative braking. The position of the accelerator pedal tells the motor controller how much torque is needed. The motor controller then changes this into a voltage or current that produces the correct torque. The rotating force can be positive or negative. When it is negative, it means the vehicle is slowing down, and energy is returned to the battery.

Regenerative Braking Explained

Regenerative Braking Extends the Life of Your Brakes

One of the benefits of regenerative braking is that it can help to lengthen the life of your brakes. Regenerative braking slows the car reducing the work of your traditional braking system. In fact, Tesla estimates that their cars experience 50 percent less brake wear than conventional gasoline cars. Elon Musk predicted that Tesla's Semi would have brake pads that would "literally last forever" because the regenerative system would save those pieces from being used extensively.

It's estimated that regenerative braking captures up to 70 percent of the kinetic energy usually lost during braking and is put back into the battery. As described above, that energy can then extend the range between needing to charge.

Does Regenerative Braking Activate Your Brake Lights?

During regenerative braking, Tesla will still activate the brake lights when the vehicle is slowing down, even if the brakes aren't being used at all. Tesla determines whether to turn on your brake lights based on your vehicle's rate of deceleration. If you're unsure if your brake lights are on, look at your Tesla screen, the car in the display shows the brake lights lit up when the brake lights are activated.

Levels of Regenerative Braking

It's important to note that regenerative braking cannot be turned off. There are two regenerative braking modes for 2020 and older models — low and standard. Tesla recommends that you use standard to maximize your vehicle's range. At some point in 2020, that choice was taken away, presumably to use all the benefits of regenerative braking all the time. However, there were some concerns, as regenerative braking can slow down the car rapidly; therefore limiting traction, the vehicle could slide. Tesla has this warning on its website: In snowy or icy conditions, Model S may experience loss of traction during regenerative braking.

Tire Configuration

The company also notes that installing winter tires may temporarily reduce regen. But the vehicle's systems are constantly recalibrating, so the feel of the vehicle will return to what the driver is used to after a few miles or trips.

You can speed up the calibration process by selecting the type of tires your vehicle is using. To select the type of tires your vehicle is using navigate to Controls > Service > Wheel & Tire Configuration > Tires and choose the appropriate tire type.

Regenerative Braking Limited or Reduced

Regenerative braking is not available or can be limited during certain conditions. If this happens, you may see a dotted line in the vehicle's power meter. If the battery is fully charged, there is nowhere for the kinetic energy to go. Consequently, regen won't work. It also has limited usage during cold weather due to a cold battery. In these cases, you can choose to activate 'Apply Brakes When Regenerative Braking Is Limited' to provide a consistent slow down experience. Tesla stated, "Your car can now automatically apply regular brakes for consistent deceleration when regenerative braking is limited due to battery temperature or state of charge." But the company did leave this as a preference, and the option can be turned off. You can activate it under Controls > Pedals & Steering.

Stopping Modes

Regenerative braking works best at certain speeds, if you're traveling too slow, regenerative braking may be limited or not available at all.

In a Tesla, your vehicle will use regenerative braking whenever you lift your foot off the accelerator pedal. However, if you're using Tesla's 'Hold' stopping mode, which allows you to drive with a single pedal most of the time, the vehicle will automatically blend in the vehicle's brakes when traveling 4 MPH (6.5 KPH) or slower.

If you're using Tesla's 'Creep' or 'Roll' stopping modes, the vehicle will never apply the brakes when lifting your foot off the accelerate, which means the vehicle will continue to roll at slow speeds when regenerative braking is no longer effect.

A Brief History of Regenerative Braking

Tesla used regenerative braking in its first car — The Roadster, in 2008. A year later, the same mechanics of the system were implemented in Formula 1. It is called KERS, which stands for Kinetic Energy Recovery System. It provides such a horsepower boost that it was banned for a season before being regulated the following year. However, this advanced system dates back to the late 1800s.

The Sprague Electric Railway and Motor Company is the earliest known use of the technology in 1886. General Electric used regen in 1936 in its locomotives, and Oerlikon, a Swiss company utilized some components of the system in its gyrobus. The Amitron, a concept electric car created by the American Motor Car Company included regenerative braking in its designs. Toyota introduced the technology to its brand with the Prius Hybrid in 1997 and GM's EV1 had regen when the company sent the cars to the crusher.

Regenerative braking is now a staple of the electric vehicle experience, not only reducing maintenance costs but also improving the vehicle's range and letting drivers accelerate and slow down with a single pedal.

How to Run Tesla Battery Health Test & Check Degradation

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Tesla offers owners an easy-to-use battery health tool, which allows users to view the degradation of their vehicle’s battery and improve the range estimate.

Battery Health

Like all batteries, electric vehicle batteries naturally degrade over time as a result of the chemical reactions that occur during charging and discharging cycles. Other factors also play a role, but the number of charge cycles and how long the battery stays at low or high states of charge play one of the biggest roles.

Your battery’s health refers to how much of its original energy capacity remains. For example, a battery at 85% health has lost about 15% of its capacity, meaning your vehicle will deliver roughly 85% of the range it had when new.

Battery Degradation

Battery degradation is worst in the first few months of ownership, and you will see the steepest degradation (1-3%) as your vehicle settles in. Part of this initial decline is due to the Battery Management System (BMS), which recalibrates to provide a more conservative and accurate estimate of your vehicle’s range and charging capacity.

According to Tesla, vehicle batteries generally degrade at a rate of about 15% per 200,000 miles, with the first year of ownership accounting for approximately 5% of this degradation. Battery degradation is less of an issue in modern EVs than many people think, because the BMS systems have become much more accurate and intelligent.

You can read more about the factors that impact the longevity of a Tesla battery.

Tesla’s Battery Warranty

Tesla offers a long warranty on its vehicles, covering both the battery and the drive units. These warranties cover up to 70% pack retention, meaning that if your battery health degrades below the 70% mark while under warranty, Tesla will replace your battery pack.

Tesla provides a drive train and battery warranty on its vehicles, which is longer than the standard vehicle warranty. This warranty guarantees the battery will have at least 70% of its original capacity within the given time period. If your battery health drops below that threshold during the coverage period, Tesla will replace the battery pack.

The warranty varies slightly based on your Tesla model and configuration, which is outlined below:

How to Test Battery Health

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While you can usually get a fairly accurate estimate of your Tesla’s battery health by calculating the amount of miles the vehicle could travel when charged to 100% and comparing that to the vehicle’s original range, Tesla has also added a tool to give you a better estimate.

Tesla has a user-friendly method of testing your vehicle’s battery health. The tool is practically identical to the one available through Service Mode, and the test and results are the same.

In order to test your vehicle’s battery health, you can navigate to Controls > Service, and then scroll down and select Battery Health. Upon tapping the button, the vehicle will display requirements for the battery test and the date and health of your last battery test.

Battery Health Test Requirements / How Long It Takes

Your vehicle will need to plugged in to a Wall Connector or Mobile Connector for up to 18 hours to run the battery test. The charger will need to be able to provide at least 5 kW of power, which is roughly about 20 amps at 240v.

The total amount of time the test will take will vary based on your vehicle’s battery size, your charging speed and the current battery level. If you’re unable to finish a battery health test and need the vehicle before it has completed, you can stop the test at any time.

Your vehicle will also need to be at a 20% or less state of charge, so you’ll need to plan accordingly.

The other requirements should be straight forwar and are listed here:

• Vehicle is in Park

• Battery level is at 20% or less

• Vehicle is connected to the Internet

• No software updates are scheduled

• No battery or thermal alerts are active

• Vehicle is connected to an AC charging station

• AC charging equipment can provide at least 5 kW of power

Running the Battery Test

During the battery test, your vehicle will discharge and charge your battery to calibrate the BMS. Therefore, the lower the state of charge, the quicker the test will run and less energy will be wasted.

Your vehicle will run the motors and heat pump or heater to help discharge energy until the batteries are nearly empty, and then begin charging.

During the test, you may hear your vehicle’s fan run at maximum speed and become very loud, especially in an enclosed garage while the vehicle is discharging. This is normal and your vehicle is just using up energy.

Battery Test Results

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Once the battery test has completed, you’ll receive a notification in the Tesla app. You can check the results in the vehicle or in the Tesla app by navigiating to Service > Battery Health.

Most vehicles will have a degradation range between 10-20%, depending on your charging habits, age and use of your battery.

If you receive a result that’s 70% or less and are within the warranty period, you should reach out to Tesla for a replacement.

Since your battery test will recalibrate the vehicle’s BMS, you may see your vehicle’s range adjusted after the test. Keep in mind that the range of your vehicle hasn’t been affected and the vehicle is simply displaying a more accurate estimate of its range.

Note: Once the battery test completes, the vehicle will keep your battery at 100%, which isn’t a good practice for battery health. It’d be a good improvement if Tesla used up energy to bring the battery level back to the charge limit if the vehicle isn’t used after an hour or two.

You should not leave your vehicle at 100% unless you have a LFP battery. Plan to go for a drive shortly after the battery test completes. If you can’t drive, we recommend running the climate system to use up some energy.

Test Limitations

Since Tesla’s battery test uses up energy and discharges your battery to near 0% and then charges it to 100%, it’s best not to perform it often. Tesla also only allows one battery test every six months, unless you go into Service Mode to perform the battery test.

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Tesla Adds Improvements to Tow Mode and Tire Service

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Tesla offers users some specific tools under its service menu (Controls > Service). These tools include features such as Car Wash Mode and Tow Mode. Just like other vehicle features, these are also updated and improved over time.

In a recent undocumented change in update 2025.2, Tesla has improved its Tow Mode feature and it’s Tire Service menu.

Tow Mode Improvements

As Tesla vehicles use electric motors, towing them with any wheels on the ground could cause the motors to backfeed energy, generating considerable amounts of heat. If done for an extended period of time, especially at higher speeds, it could cause damage since the vehicle isn’t running its coolant loop to dump waste heat.

To help solve this problem, Tesla provides Tow Mode, which breaks down the steps needed to tow a Tesla. It also provides an easy way to put the vehicle in neutral and disengage the parking brake.

The improvement to Tow Mode now displays a checklist similar to Car Wash Mode. Each item in the list will light up green or red, depending on whether it’s already in the correct setting for Tow Mode.

Tesla has also added a readout of the low-voltage battery. While this could be useful for anyone wanting to check the current on their LV battery, it’s an important detail to be aware of if you’re towing because the vehicle’s high-voltage battery has been run down. All of the vehicle’s electronics are powered by the LV battery, and depleting it could cause the display to not turn on, as well as prevent access to certain vehicle features.

The vehicle shown in the diagram is also unique to the vehicle you are driving - a Model 3 will display a Model 3, while the Cybertruck will display a Cybertruck - just a subtle touch of Tesla precision to the entire presentation.

You can activate or check out Tow Mode from Controls > Service > Tow Mode.

Tire Service Improvements

Tesla has also improved its Tire Service menu, which is now tied into Maintenance History. These menus allow you to switch the wheels and tires your vehicle is using. It’s important to note that the wheel is not only used in the vehicle’s visualization, but also has impacts on the vehicle’s ability to accurately predict its range.

In the Tire menu, Tesla has added a Service Type dropdown, allowing you to select why you’re switching your tires. You can choose whether you’re rotating your tires, replacing them, or swapping them out for seasonal tires. This change will then be recorded in Maintenance History, allowing you to track the maintenance of your tires, including the date of the last maintenance and the ability to see the mileage on your current set of tires.

You can navigate to the Wheel and Tire menu by going to Controls > Service > Wheel & Tire.

The updated Wheel and Tire menu

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Cybertruck

As a note, the Tire Service improvements are not fully implemented in the Cybertruck in the primary menu. If you wish to mark a Seasonal Tire Change in your Cybertruck, you’ll need to head into Service Mode and add a Correction Code for Seasonal Tire Change from there.

We expect Tesla to fix or add this in an upcoming update for the Cybertruck.

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