How Tesla's Regenerative Braking Works

By Kevin Armstrong
Tesla offers three stopping modes
Tesla offers three stopping modes
Not a Tesla App

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
Tesla's power meter, also known as the regen bar or line
Not a Tesla App

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?

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.

Tesla's Dojo Project Faces Leadership Shakeup

By Kevin Armstrong
Dojo Leadership Shake up
Dojo Leadership Shake up

Ganesh Venkataramanan, Tesla’s project lead for its ambitious Dojo supercomputer project for the past five years, has left the company. Bloomberg reported this development, stating that the news was confirmed by sources familiar with the matter. Peter Bannon, a former executive at Apple Inc. and a director at Tesla for the last seven years, has now taken the helm of the project.

Venkataramanan's departure from Tesla last month is now stirring conversations about the potential impacts on Tesla's future initiatives. His contributions to the Dojo project have been pivotal, especially in designing the custom D1 chip that powers the supercomputer. Venkataramanan, with his extensive experience, including a significant tenure at Advanced Micro Devices Inc. (AMD), was a crucial asset in setting up Tesla’s AI hardware and silicon teams in 2016.

Dojo: A Cornerstone for Tesla’s Self-Driving Aspirations

The Dojo supercomputer is a critical element of Tesla's strategy to enhance its self-driving capabilities. Designed to train machine learning models integral to Tesla's autonomous systems, Dojo processes vast amounts of data captured by Tesla vehicles. This rapid data processing is essential for improving the company’s algorithms, with analysts suggesting that Dojo could be a significant competitive advantage for Tesla. In a recent estimation by Morgan Stanley, the project could potentially add $500 billion to Tesla’s value.

Elon Musk has been vocal about the company's commitment to the Dojo project, planning an investment exceeding $1 billion by the end of 2024. The project's importance was underscored in Tesla's decision to shift from relying on Nvidia Corp.’s supercomputers to developing Dojo, poised to rival systems from Hewlett Packard Enterprise Co. and IBM.

Looking Ahead: Impact and Future Prospects

The recent leadership changes raise questions about the future direction of the Dojo project. Venkataramanan's exit, coupled with the departure of another critical artificial intelligence player from Tesla last year, Andrej Karpathy, signals a transition period for the company’s AI and self-driving teams.

However, Tesla's robust talent pool, blending experienced and emerging professionals, offers a silver lining. Bannon's promotion to lead the Dojo project is seen as a strategic move, leveraging his experience and insights gained from his tenure at Apple. Moreover, the recent installation of Dojo hardware in Palo Alto, California, marks a step forward in centralizing and enhancing the project’s capabilities.

Tesla’s ambitions for Dojo extend to making it one of the world’s top supercomputers. The company envisions reaching a computational capability of 100 exaflops* by October 2024, a testament to its commitment to advancing artificial intelligence and self-driving technology.

* Confused about "exaflops?" "Flops" stands for Floating Point Operations Per Second. It's a way to measure how fast a computer can process data. "Exa" means a billion billion, or 1, followed by 18 zeros (1,000,000,000,000,000,000). So, when we say a computer can perform 100 exaflops, it can do 100 billion billion calculations per second. That's incredibly fast!

New Parking Visualizations and Custom Locking Sounds Also Coming in Tesla's Holiday Update

By Kevin Armstrong
Tesla is adding a new 'High Fidelity Park Assist' feature in this year's Holiday Update
Tesla is adding a new 'High Fidelity Park Assist' feature in this year's Holiday Update

Following initial reactions to Tesla's 2023 Holiday Update, Elon Musk acknowledged the need for improvement, stating, "We need to step up our game." His post on X was followed by Tesla shedding more light on the Holiday Update than what was in the initial leak.

Call me old, but I remember a time when you bought a car, and that was it; the dealer and manufacturer didn’t give you anything else. So is the Tesla community acting a little bit spoiled here? Absolutely. But it also shows how high Tesla has set the bar with its previous Holiday Updates.

Initial Release and Feedback

The initial release of the 2023 Holiday Update, version 2023.44.25, received mixed reactions from the Tesla community, with some owners expressing disappointment over the lack of groundbreaking new features. But the newly announced features may serve as better stocking stuffers.

The initial rollout included something owners have been asking for, the blind spot monitor. The camera that turns on when you change lanes will now have a red color added if there is something in your blind spot. It’s not clear whether it will be accompanied by a tone.

Here are other features in the leaked update that are being tested by employees:

Navigation and Safety Features: Including symbols for speed cameras, stop signs, and traffic lights in navigation, and the automatic 911 call feature in case of an accident.

Trip Planning via Tesla Mobile App: Allowing for more detailed trip planning, including multiple stops and charging points.

Apple Podcasts Integration: Allowing users to sync with Apple devices for a seamless podcast experience, directly addressing the demand for a richer in-car entertainment system.

New Games and Enhancements: The update brought updates to Tesla Arcade, with Beach Buggy Racing and Polytopia Diplomacy updates, as well as the Vampire Survivors Chilling update.

Light Show Improvements: There’s a new light show that’s included with your vehicle. You’ll also be able to upload several light shows on a single USB drive and pick one from the vehicle, instead of having to use multiple USB drives, one for each light show.

More Live Sentry Mode Cameras: You will now be able to view the B-pillar cameras directly from the Tesla app. This brings the number of viewable cameras in the app up to seven. The only ones still missing are the alternative front-facing cameras that are telephoto and wide-angle, which wouldn’t bring much additional value. Although the B-pillars are viewable in the app with this update, they will still not be used to record during Dashcam or Sentry Mode events.

High-Fidelity Park Assist

Tesla's High Fidelity Park Assist
Tesla's new parking assist feature will dynamically recreate scenes in real-time

In response to the feedback and Musk's statement, Tesla unveiled additional features in its updated holiday update, including an improved park assist with enhanced visualizations.

This feature provides a 3D reconstruction of the vehicle's surroundings while parking, akin to a 360-degree camera system found in other high-end vehicles. The system is clearly leveraging improvements to Tesla Vision to create the surrounding environment, such as cars, pillars and walls.

This feature also appears to change the color of objects depending on how close they are to your vehicle. In the image we can see the pillars are orange, but if we look closer, the object behind the vehicle is also orange near the bottom. The sides of the vehicles next to the Tesla also have a slight hint of orange, indicating their proximity.

However, it looks like this feature may be even better than it initially looks. The vehicles in the image aren’t just predefined 3D models that Tesla created, like the ones used in Autopilot visualizations. These models appear to be dynamically created using vision, so that no two cars would look alike, much more similar to what LiDar is able to achieve. The visualization provides a true representation of the environment around the vehicle. You can see that each vehicle is made up from layers and have blurred edges toward the rear, where the camera would have a hard time seeing.

These 3D models could be a sneak peek at the future of FSD visualizations.

High-Fidelity Park Assist Requirements

A big question on everyone’s mind is who will receive this new park assist feature. Tesla didn’t address this in their post on X besides providing a disclaimer that the features in the holiday release are subject to model and region availability. Tesla often likes to test features in select markets before making them available everywhere. It’s hard to say whether that will be the case here. There likely aren’t any legal ramifications around providing visualizations, so that’s a good sign that this feature will be available in most regions, either in the holiday update, or soon afterward.

However, there are still questions around which models or hardware will be required. From the image shared, we can see it’s offered on a Model Y, removing any speculation of it possibly requiring the HD radar in the new Model S/X. We also don’t think it will require FSD hardware 4.0, so the remaining questions are whether it requires MCU 3, or the FSD package.

Given that Tesla is calling this Park Assist, it doesn’t appear to be linked to Auto Park, which is a FSD package feature. When Tesla rolled out visual and audio alerts for vehicles without ultrasonic sensors, it called the feature Park Assist, and that was available to all owners.

Whether this improved Park Assist feature requires a vehicle with MCU 3 will depend on the level of processing power required. It’ll certainly require more than the current visualizations given that its building the scene in real-time, so we’re hopeful that it’ll work on MCU 2 vehicles too, but we just don’t have enough information right now to make the call.

Custom Lock Sounds

Soon you'll be able to choose a custom locking sound for your car
Soon you'll be able to choose a custom locking sound for your car
Not a Tesla App

Tesla also announced a fun and whimsical feature that allows owners to customize the lock sound of their Tesla. No longer will you need to listen to the car’s horn when it locks as you walk away. Now you’ll be able to customize the lock sound of the vehicle. Tesla is including several options, including sounds like a screaming goat, a jingle, a rubber ducky, a quack sound, an old school horn and applause. However, you’ll also be able to upload your own file to create a truly unique experience.

You can pick anything, from a bird’s tweet to a favorite video game sound. You’ll only be limited by the maximum upload file size, which according to a Tesla engineer, is a 1MB file in WAV format, which is roughly about 40 seconds at good quality.

This feature is possible due to the vehicle’s external pedestrian warning speaker. So if you have Tesla’s Boombox feature or your vehicle makes a sound when traveling under 20 MPH, then you should receive this fun enhancement.

Rear Seat Audio and Gaming

You'll now be able to play games on Tesla's rear screens
You'll now be able to play games on Tesla's rear screens

Enhancing the Tesla Arcade experience, passengers in the rear seats can now play games on the rear touchscreen. This feature, especially when paired with Tesla Arcade’s compatibility with PS4, PS5, Xbox Controllers, and rear-screen Bluetooth Headsets, is a welcome addition for families and long trips.

Much like the new Model 3, which received rear audio over Bluetooth support in the 2023.38 update, the new Model S and Model X will also receive this ability in the holiday update.

New Game - Castle Doombad

Tesla announced one other feature in the 2023 holiday update that hadn’t been previously leaked, and that’s a new game called Castle Doombad. Castle Doombad is a single player tower defense, puzzle-like game that’s currently available on iOS and Android, but has an upcoming release on PC and the Nintendo Switch. This game is expected to require MCU 3.

Release Timeline

The rollout of the 2023 Holiday Update is expected to follow a similar timeline to last year. Tesla announced that the update will roll out starting next week. However, it’s not clear whether this will also include FSD Beta testers that are on a 2023.27 update.

Looking back at the 2022 Holiday Update, it started on December 13 and took about a week to get to the entire fleet.

Speculation on Future Features

Like a spoiled child on Christmas morning, Tesla owners still ask, “Is that it?” Well… possibly, but there may be more to look forward to early next year as Tesla builds off of the new High-Fidelity Park Assist feature.

Advanced Smart Summon: Upgrading the Smart Summon feature to be more intuitive and efficient, especially in complex parking scenarios.

Reverse Summon / Park Seek: What happened to Tesla dropping its passengers and driver off at the location and then finding a parking spot on its own?

Enhanced FSD Visualizations: Expanding the Full Self-Driving visualizations to more regions or models or completely recreating the FSD visualizations using the same neural networks Tesla is using for the High-Fidelity Park Assist feature.

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Although we share official Tesla release notes, we are not affiliated with Tesla Motors. We are Tesla fans and supporters.

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Take a look at features that Elon Musk has said will be coming soon.


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