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UPDATE (to the original post): TESLA HAS CONFIRMED THEY ARE DOWNGRADING CARS WITHOUT PERMISSION. HERE IS WHAT WE KNOW:

SITUATION

When a battery cell is built, it is built to a certain specification in regard to the amount of charge it can hold. Insofar as Tesla Lithium Ion cells are concerned, they are built with a nominal voltage of 3.66V. This is commonly called Vnom.

Each cell can take more charge, or less charge. But care has to be taken as to how much more, or how much less, as too much or too little can often damage the cells. The amount of charge held within a cell is determined by the cell’s voltage. The higher the voltage, the higher the charge. (Purists will weep at this awful generalisation, but that is all it is, a generalisation).

The maximum Voltage in Tesla Cells is 4.2V. This is commonly called Vmax. (4.2V is virtually an Industry Standard setting for lithium ion EV cells).

The minimum Voltage in Tesla Cells is 3.12V @ <1%. This lower figure is commonly called Vmin.

In a Model S70, for example, when all the cells are at Vmax, ie 4.2V, the combined total charge held in the pack equals 70 kWh.

BMS (BATTERY MANAGEMENT SYSTEM)

WHICH CARS HAVE BEEN VOLTAGE CAPPED

EFFECT OF CAPPING



EFFECT ON RANGE



It has been widely tested, and confirmed that Capping has been achieved by the software reducing the applied Vmax of the cell bricks in the pack (each brick is 74 individual battery cells wired in parallel). In many cars suffering from batterygate, they have changed Vmax from 4.2V to about, let's say, 4.07V. Not much difference you might think. But when all the bricks are now at 4.07V (the new Vmax) the combined total now only equals 59 kWh, and not the original 70 kWh for model S70 as an example. The net effect is the battery appears to have lost 10 kWh. It is not actually a loss of 10 kWh, it is just that 10 kWh has been made unavailable for use.



Let’s look further at the impact of a small drop in voltage. A Model S70 owner, for example, reported the observation below:



- At 4.2V his 100% range was 225 miles

- After capping to 4.07V his Range was 192 miles

- After a slight increase to 4.1V his Range was 199 miles



So, even though the Voltage drop looks insignificant, the actual effect is tangible.



A smaller battery obviously provides less range, and this is what most people first notice. Their range appeared to have gone down. Many people reported this Loss of Range. But of course that loss is not the cause, or the fault, it is merely the consequence of a smaller battery. Think replacing a 70 litre fuel tank with a 59 litre fuel tank.



This is exactly the procedure Tesla use when they used to sell a car as a S60 with a restricted 75 kWh battery. They have simply reduced the Vmax to a level that corresponds with 60 kWh. They then allow you to “uncork” the battery, at a price. You pay the money, they change the Vmax to 4.2V, and bingo, you now drive a S75.



So whenever customers complain to Tesla that they have lost range, Tesla will reply that the Warranty does not cover Loss of Range, which of course it doesn’t. So Tesla rejects the claim.



They also reject any claim about loss of Capacity due to voltage cap. But normal loss of Capacity (commonly called Degradation) is described in the Warranty as a loss resulting from gradual usage, and over time. We all expect that to happen. But the key point is, this batterygate loss of Capacity is due to voltage cap and has not been gradual. Nor has been over time. It has been sudden, virtually overnight.



It is also VERY important to note that when batteries do degrade, which they will, the cell voltage limit will not change. A very old battery that is only holding, say 50% of its original charge, will still (try to) charge to 4.2V. It may not get there but Vmax will certainly not reduce. It is not the voltage cap that drops, just the energy contained within the cell. So a 50% degraded battery may only be able to charge to 50%. But the battery will not report that as 50%. A degraded battery will use its charge up more quickly. The Cell will charge up more quickly, and deplete more quickly. This will be reflected in higher Wh consumption per mile. So if the reduction in capacity (due to voltage cap) is due to an imposed change of cell Voltage, i.e. changing Vmax, that is not, in any way, normal degradation. That is 100% artificial degradation, achieved through software changes to the cell voltage limits.



EFFECT ON PERFORMANCE



The volt cap also reduces horsepower (power as in kW). In an electrical system, power is determined by multiplying volts times amps (V*A=Watts). Lower volts means lower horsepower (available kW).Furthermore, because the voltage capping in effect reduces your actual SoC% (your capped 100% SoC is not the real 100%, rather it’s 90% of your old 100% SoC), your max power is reduced. The P85DL cars lose the most power to volt capping, but all cars will have reduced performance.​

CAPPING CAUSES

OWNER CAUSED



It has frequently been suggested that Batterygate is a result of owners that:

Supercharged (or DC charged) too frequently. Charged to a very high, or very low State of Charge (SoC), i.e., frequently to 100%. Normally operated to a high range of SoC, i.e., normally between 70-100% SoC, rather than say 20%-80%. Anecdotal evidence from many dozens of owners suggest none of these are likely reasons. There are many examples of owners that did meet the criteria but were not capped, and many that didn’t meet the criteria, but were capped. There are so many contra examples, that it is difficult to conclude any of these reasons is a credible reason as the trigger for Capping. Tesla have informed some owners verbally, that their DC history is the reason their car has been capped. Of course that is an unusual argument as ALL charging is DC charging as far as the car is concerned. The battery can only take DC. Tesla has never warned owners that frequent Supercharging was a bad thing of itself, that might damage their battery. Indeed in the early days Tesla used to site Superchargers in cities, rather than in between them, so that owners had access to charging facilities. Perhaps they were not aware that Supercharging was so detrimental, or perhaps the trigger is another reason.



However, even if excess Supercharging, or just excessive DC charging is the reason, that charging, and the way in which the BMS deals with it, is entirely within Tesla’s control. As was the advice given to owners by Tesla on charging. The only advice given by Tesla to owners was that, if possible, owners should restrict the charge to 90% as that's better for the battery, but to charge to 100% whenever you need it. Doing it occasionally is fine. Owners have no influence over this. So if, in hindsight, Tesla got the BMS coding wrong, or didn’t taper the charge rate and the battery cooling/heating protocols sufficiently, or gave incorrect advice about charging, that must surely be Tesla’s responsibility, not the owners.



CAR CAUSED



If it is not Owner Caused, then it is perhaps due to something within the car.

Only pre facelift cars have been affected, ie built prior to Summer 2016.

Deduction: Facelift cars can be excluded from the cause. Only smaller batteries (60, 70 or 85 kWh) have been affected.

Deduction: 90 kWh batteries can be excluded from the cause. 60 and 70 kWh batteries only have 14 Modules (6216 cells) and are 350V batteries. 85 kWh batteries have 16 Modules (7104 cells) and are 400V batteries.

Deduction: The number of Modules or Battery Voltage can be excluded from the cause. 90 kWh batteries have 16 Modules and are 400V batteries. They were introduced in 2015, so well within the pre facelift period. 100 kWh batteries were introduced in Summer 2016, i.e., outside of the pre facelift period. There should be no pre facelift vehicles with 100 kWh batteries.

Deduction: 100 kWh batteries can be excluded from the cause. 90 kWh batteries were actually 85 kWh batteries, but with the new ‘Gen 2’ battery cell. Gen 2 Cells introduced Silicon into the Graphite Anode. Silicon holds greater energy density. So the increase in energy wasn’t as a result of a larger battery, or different design, simply a change of Cell type. It was described by Tesla as “a range upgrade due to the improved cell chemistry with the introduction of silicon into the graphite Anode”. Deduction. Only 90 kWh batteries had the new Gen 2 Cell. All 60, 70 and 85 batteries had the old Gen 1 Cell. The only Common Factor that links pre facelift, and smaller batteries (60, 70, 85 kWh) is the old Gen 1 Cells. There may be other common factors, but no-one across the globe has been able to identify one. ​ It has frequently been suggested that Batterygate is a result of owners that:Anecdotal evidence from many dozens of owners suggest none of these are likely reasons. There are many examples of owners that did meet the criteria but were not capped, and many that didn’t meet the criteria, but were capped. There are so many contra examples, that it is difficult to conclude any of these reasons is a credible reason as the trigger for Capping. Tesla have informed some owners verbally, that their DC history is the reason their car has been capped. Of course that is an unusual argument as ALL charging is DC charging as far as the car is concerned. The battery can only take DC. Tesla has never warned owners that frequent Supercharging was a bad thing of itself, that might damage their battery. Indeed in the early days Tesla used to site Superchargers in cities, rather than in between them, so that owners had access to charging facilities. Perhaps they were not aware that Supercharging was so detrimental, or perhaps the trigger is another reason.However, even if excess Supercharging, or just excessive DC charging is the reason, that charging, and the way in which the BMS deals with it, is entirely within Tesla’s control. As was the advice given to owners by Tesla on charging. The only advice given by Tesla to owners was that, if possible, owners should restrict the charge to 90% as that's better for the battery, but to charge to 100% whenever you need it. Doing it occasionally is fine. Owners have no influence over this. So if, in hindsight, Tesla got the BMS coding wrong, or didn’t taper the charge rate and the battery cooling/heating protocols sufficiently, or gave incorrect advice about charging, that must surely be Tesla’s responsibility, not the owners.If it is not Owner Caused, then it is perhaps due to something within the car.

NET EFFECT OF BATTERY CAPPING

CALCULATION OF AMOUNT OF CAPACITY BLOCKED BY CAPPING

Method:

REASONS GIVEN BY TESLA FOR ARTIFICIAL CAPPING

Yes, it appears to be a very small percentage of owners.

The effect is not ‘when charging to maximum state of charge’, it is a linear reduction across the board.

Yes, they are working on improving it, and have rolled out an update to improve it. The update (2019.28.2.5) does appear to somewhat achieve this. In fact what it does, is increases Vmax from 4.07V to 4.08V. This gives an apparent increase in range, but only of about 5 miles or so, nothing like the 20-30 miles lost to start with.

This update appeared the day following the submission of a potential Class Action Lawsuit in the U.S. It would be fair to say there is a great deal of suspicion on TMC that this quick update had more to do with Tesla being able to say to the court that not only are they working on a solution, but look, some owners are already seeing an improvement. Pure supposition on their part, and there is no way of knowing if this is correct or not.

POSSIBLE REASONS FOR THE CAPPING

Why the capping?

Condition X and Condition Z

It seems to meet all the Tesla-defined criteria. If the weak cells are still, just, within spec, then Tesla can describe the battery as healthy.

If they are deteriorating faster than expected, reducing the battery capacity will make for a much less stressful condition, which should delay that decay.

Capping the battery, (and indeed restricting charge rate), will help reduce decay and lengthen battery life.

It would meet with Tesla’s statement that the download was “to secure longevity of the battery’s life span”.

Is it plausible that some cells are inferior?

Why only some cars?

CONCLUSIONS

Update 2019.16.1.1 (and later) contained the batterygate software.

Affected batteries appear to have had their Vmax reduced to a figure below the normal 4.2V.

This reduction of Vmax has reduced the size of the usable Capacity.





This reduction of Vmax has reduced the car’s performance.

This reduction of usable Capacity is reflected in reduced range.

This reduction of usable Capacity is reflected in the resale value of the impacted cars.

Tesla have robustly refused to explain why they have capped some vehicles and not others.

If the response is “there is a fault or issue with your battery”, then you could claim a fix via the Warranty





If the response is, and this is very likely, “there is no fault with your battery”, “your battery is healthy”, and “this is all done for the health or longevity of your battery”, your position should be “if the battery is healthy with no issue then there should be no need to cap it”. Demand the capping to be removed if there is no issue with your battery.

MORE TO KNOW



1. THIS IS NOT DEGRADATION



2. AM I AFFECTED?

Model S/X

Charge to 100%. Using CANBUS tools, if your car’s cell volts @ 100% are close to 4.2v (real world readings are usually 4.198 or similar, don’t expect true 4.2v but you should be very close) you are OK. If you consistently charge to 4.18v or less @ 100% regardless of temperature, etc., you have probably been capped. Please add yourself to this spreadsheet:



Tesla battery capacity loss with FW 2019.16.2



Model 3





Error Messages:

The error messages from a capacity and charge rate capped Model year 2014 S85 battery pack, reported by







​ Charge to 100%. Using CANBUS tools, if your car’s cell volts @ 100% are close to 4.2v (real world readings are usually 4.198 or similar, don’t expect true 4.2v but you should be very close) you are OK. If you consistently charge to 4.18v or less @ 100% regardless of temperature, etc., you have probably been capped. Please add yourself to this spreadsheet:The error messages from a capacity and charge rate capped Model year 2014 S85 battery pack, reported by an affected owner

3. IMPORTANT TO FILE AN NHTSA COMPLAINT



4. CLASS ACTION



5. USEFUL LINKS