As Tesla continues to push the capabilities of its hardware as it prepares for autonomy with FSD Unsupervised, there has been a distinct divergence in features between HW4-equipped vehicles on FSD V13, and HW3-equipped vehicles on FSD V12.6.
There are definitely reasons for this, and Tesla hacker Greentheonly, over on X, went into great detail on some of the reasons why this divergence has continued and is likely to continue.
If you’re interested in some background, we recommend the following articles. Although they’re not necessary, you may enjoy reading them before diving right in if you enjoy this topic.
Back in the summer of 2024, we reported that Tesla’s HW4 had yet to reach its full potential, and that HW3 still had some compute to work with. However, FSD has undergone a rapid evolution - there are now fundamental differences driven by the hardware capabilities and sheer scale of the latest builds of FSD.
FSD V13’s Gargantuan Neural Networks
FSD V13 is a substantial leap for Tesla. It features substantially larger neural networks - the core brain that processes all the environmental data and makes decisions. Those networks are far larger in V13 than in V12, which results in a much smoother and human-like expereience.
Tesla’s FSD computers contain two nodes. According to Green’s analysis of FSD V13, Node B, which handles the actual end-to-end driving logic, tripled in size from 2.3 GB in V12 to a staggering 7.5 GB in V13. That’s a substantial increase, and one of the main reasons why HW3 can’t handle FSD V13. While Interestingly, Node A on HW4 remains similar in size to FSD V12, using up about 2.3 GB.
However, this massive size is also pushing the limits of HW4. While this isn’t necessarily a big problem immediately - at the end of the day, there is a limited amount of compute and ram available and model sizes will likely grow in the future. In fact, Tesla is planning to scale model sizes in the next FSD version and has already said they’ll need to optimize them, as context size is limited by on-board memory.
HW3 Limitations
Since HW3 can’t run the latest FSD models, where does this leave millions of Tesla vehicles equipped with the now-legacy FSD hardware? Are they hitting a dead end? Not exactly - Tesla has promised to replace HW3 computers with new units during the Q4 2024 Earnings Call, but only for those who have purchased FSD and only if Tesla is no longer able to update HW3 vehicles.
There’s no doubt Tesla hopes to achieve autonomy and then work backwards to make it compatible with HW3, but that’s unlikely to happen with the limited ram available on HW3.
Tesla’s AI team has continued to say that they’re still working on updating HW3 vehicles - but that they will be taking a backburner to updates for HW4 until the team can optimize the model efficiently enough to run on the smaller footprint. That means V12.6 isn’t just V13 “lite” - it is a distinctly different software branch tailored specifically for HW3’s capabilities.
Green's analysis showed that HW3 under V12.6 runs NNs totaling 1.2 GB on Node A and 3.1 GB on Node B, which is significantly smaller than the footprint of V13. Back in November, we discussed how Tesla is running a smaller and optimized FSD model on HW3, with the specific goal of achieving similar performance to V13. FSD V12.6 appears to be the current implementation of that smaller model strategy.
Green also found that of the total neural nets used for FSD, 135 are shared between the current V12.6 and FSD V13.2 releases, which is the result of Tesla’s AI team working to optimize and refine the V13 model for HW3. So some neural nets are shared between the two sets of hardware, while others are specific to HW3 or HW4.
AI4 in the Future
The fact that V13 is already stretching HW4’s limits makes us wonder about Tesla’s imminent release of AI5. Last year, Tesla mentioned that AI5 would be 18 months away - which is now about 8 months away, and potentially even sooner to help solve the autonomy problem.
At the same time, Tesla is looking to launch Unsupervised FSD in June in Austin, Texas, with presumably HW4, which would indicate that they’re confident in its capabilities.
Unless Tesla launches the Robotaxi network with AI5, we don’t believe AI5 will be a “must have” item. Undoubtedly, it will result in similar improvements to HW4 compared to HW3. However, the software needed to take advantage of the newer hardware could still be years away.
All eyes will be on Tesla’s Robotaxi network launch and the hardware required for it. For now, HW4 owners are in good hands with future updates are on the horizon, and we’re certainly excited for what’s next.
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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.
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:
Vehicle
Warranty
Model S, Model X, Cybertruck
8 Years / 150,000 mi (240,000km)
Model 3 / Model Y RWD
8 Years / 100,000 mi (160,000km)
All Other Model 3 / Model Y
8 Years / 120,000 mi (192,000km)
How to Test Battery Health
Not a Tesla App
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
Not a Tesla App
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.
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.
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
Not a Tesla App
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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