How much max range have you lost already?

[HaulingAss]

My Cybertruck has zero reported degradation since new 3,200 miles and 5 months ago. I still have 318 miles.

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[RickJ19Zeta8]

The -only- way to accurately check battery health is by running the built in BMS calibration routine found in the service sub-menu. Which will nearly fully discharge the pack, fully charge it and balance all the modules. It takes a day+ to run.

BMS calibration drift is just a fact of daily charging routines. It means that the on-screen value, and any value pulled by Tessie and Teslamate are wrong. Those apps are worse than worthless to record and compare battery health because the data is junk, but everyone still argues and thinks it’s real. They make people worry about a problem that doesn’t exist.

You have an 8 year, 150,000 mile warranty on your pack. Switch your charge icon to % and just charge and drive the truck.

 

[AlmostHuman]

The -only- way to accurately check battery health is by running the built in BMS calibration routine found in the service sub-menu. Which will nearly fully discharge the pack, fully charge it and balance all the modules. It takes a day+ to run.

BMS calibration drift is just a fact of daily charging routines. It means that the on-screen value, and any value pulled by Tessie and Teslamate are wrong. Those apps are worse than worthless to record and compare battery health because the data is junk, but everyone still argues and thinks it’s real. They make people worry about a problem that doesn’t exist.

You have an 8 year, 150,000 mile warranty on your pack. Switch your charge icon to % and just charge and drive the truck.

Let’s agree to disagree here.
TeslaMate has a lot of great data in it. I do agree that doing the calibration routine will give amazing data but that doesn’t make the data other services can get junk.

You should also tell people not to run that calibration all the time. It will put extra unnecessary cycles on your battery.

 

[Jager]

SOC reported by the vehicle is almost entirely, simply, the voltage reported out by the pack. Individual cell voltage variance can be a factor, but a healthy pack tends to see minimal such variation. Likewise temperature, which is why we see a slight decrease in range when temperatures decline... because the cells individually, and the pack as a whole, is putting out slightly less voltage.

"Calibration drift," to the extent that such a thing is a thing at all, is an overwrought concept. What, exactly, is supposed to have drifted?

Third-party apps, at least legitimate ones, aren't inventing the data they report. They are simply extracting the data the vehicle is already reporting (the vast majority of which is hidden), and displaying it to the user. Not saying all those apps are equal. Tesla's vehicles don't report Degradation, for instance. But they do report the necessary data from which degradation can be easily calculated.

If the BMS Calibration procedure under the Service menu was periodically required to correct "drift" and restore accurate SOC measurements, performing that procedure would show marked changes to vehicle range immediately after running it. And yet we don't hear of that. Nor do we hear of Tesla Service recommending that procedure except in unusual cases.

Tesla's battery and BMS technologies are pretty solid, IMO.

 

[RickJ19Zeta8]

SOC reported by the vehicle is almost entirely, simply, the voltage reported out by the pack. Individual cell voltage variance can be a factor, but a healthy pack tends to see minimal such variation. Likewise temperature, which is why we see a slight decrease in range when temperatures decline... because the cells individually, and the pack as a whole, is putting out slightly less voltage.


Tesla's battery and BMS technologies are pretty solid, IMO.

No, SOC is not simply voltage reported out by the pack. The lithium ion cell voltage curve has a voltage hook at the bottom of the cell capacity, a voltage hook at the top of the cell capacity, and a long flat voltage plateau for the majority of the cells capacity change.

That plateau is so slight, that the voltage measurement error and ADC (analog to digital converter) notching isn't accurate enough to estimate how much charge is in the cell.

-ALL- Automotive BMS systems use a process called coulomb counting, which is the integration of the amperage measurement in and out of the cell vs. time. The system knows where it started and what that max capacity is, then tracks it from the starting point. That is the SOC reported by the vehicle and recorded by Tessie. It is incredibly precise, but due to the nature of its process, its error is additive.

If the vehicle charges many times (every charge, regen braking event, every short drive) within the cell plateau (lets call that 20-80% SOC), then the system is wholly reliant on coulomb counting. The amperage measurement error is slight, but over 10,000 charge / discharge events (ever pedal application and regen event, not full pack charges) that error slowly builds. On average its between 2-4% of the total pack capacity.

Now..... the system CAN adapt and reset itself. A full charge to 100% will pull the cell into the voltage hook and the system can start from its last know "full capacity". But the system doesn't know if that full capacity amount has changed. It simply eliminates the built up error in the coulomb counting. Similarly, if the pack is discharged near the bottom of the cell voltage, the system can re-estimate the pack capacity change as the battery recharges towards 100%. But unless you do the full discharge and charge to 100% at a slow enough charge rate per the service procedure, that estimate is still..... an estimate with error in it.

Tessie and Teslamate's data is junk because you have no idea how much error has been built up each time a data point was taken. It doesn't matter that you have millions of points of data. Junk data IS STILL JUNK. And any point your vehicle pulls to compare against could be spot on or 2-4% off or more. And considering people here are arguing about 1% changes in pack capacity..... this point matters.

I'm not advocating that people do a pack BMS calibration. The opposite. I'm saying that a pack calibration is the only way to accurate estimate pack capacity. Ignore the data coming out of Tessie, just drive the truck and let the BMS system do its thing.

 

[HaulingAss]

The -only- way to accurately check battery health is by running the built in BMS calibration routine found in the service sub-menu. Which will nearly fully discharge the pack, fully charge it and balance all the modules. It takes a day+ to run.

BMS calibration drift is just a fact of daily charging routines. It means that the on-screen value, and any value pulled by Tessie and Teslamate are wrong. Those apps are worse than worthless to record and compare battery health because the data is junk, but everyone still argues and thinks it’s real. They make people worry about a problem that doesn’t exist.

You have an 8 year, 150,000 mile warranty on your pack. Switch your charge icon to % and just charge and drive the truck.

The on-screen values can drift and become inaccurate if the pack is not charged and discharged very fully, but they are not automatically "junk". If the battery has been well discharged and sat for a few hours and then well-charged, the on-board BMS will re-calibrate, and they will be the best available info on the state of degradation.

The accuracy of the values depends upon how long it's been since the battery was discharged and charged fully enough to perform an accurate re-calibration of the on-screen range numbers. In other words, those numbers are VERY useful, you just need to know when you can trust them and when they might contain significant inaccuracies.

 

[AlmostHuman]

just drive the truck and let the BMS system do its thing.

I completely agree. Still like stats and data

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