[rst89]

Originally Posted by avishar

Tesla Battery Degradation data

Nissan Leaf Battery Degradation data

There is one quote about charging to 80 % and discharge till 0 % than to charge to 100 % and discharge to 20 % in Nissan Leaf report. If you are an EV car manufacture, I wouldn't allow any battery to discharge till 0%. This is for protection of components. When our team designed battery management systems for European OEM, we have charging cut off levels. When only 12% charge is left, we used to log a Diagnostic Trouble code(DTC) but perform no action. When 4% charge was left, we used to open contactors and log a DTC so that car comes to a safe halt. It's not a mobile phone to use till 1%. Anyways, that 4% boundary can be calibrated by OEMs and we used to get the requirements for same from the OEMs.

Regarding age of battery, the battery management system has a battery core software component. It stores the age of battery in non volatile memory since the BMS is flashed and powered with battery modules. The battery core will use this counter and run it's own algorithms to extract the best out of the battery. Also it looks like our team has overlooked the scenario of how the battery core will perform when the whole battery gets replaced. I will have to get more information from my colleagues about ageism of batteries as I didn't work on battery core part of BMS.

[saikarthik]

Originally Posted by Ravi Parwan

2. The SoC of a battery is estimated with the "net" current outgo from the battery. The storage is calculated on the last known full charged state of the battery. The net input and outgo of current is stored with the device and on the chip in the battery.

In second scenario, the current outgo from a battery once charged will be stored on the battery chip, but if the battery is left to discharge, not sure if that will be lead to inaccuracy in charge calculations.
.

This was the problem with earlier BMS (battery management systems), but now the accuracy of coulomb counting(current outgo) has increased a lot due to advanced learning and computing incorporated in BMS related to previous SoC and current battery state. Even aging, degradation, temperature etc.

[rst89]

Originally Posted by rst89

There is one quote about charging to 80 % and discharge till 0 % than to charge to 100 % and discharge to 20 % in Nissan Leaf report. If you are an EV car manufacture, I wouldn't allow any battery to discharge till 0%. This is for protection of components. When our team designed battery management systems for European OEM, we have charging cut off levels. When only 12% charge is left, we used to log a Diagnostic Trouble code(DTC) but perform no action. When 4% charge was left, we used to open contactors and log a DTC so that car comes to a safe halt. It's not a mobile phone to use till 1%. Anyways, that 4% boundary can be calibrated by OEMs and we used to get the requirements for same from the OEMs.

Regarding age of battery, the battery management system has a battery core software component. It stores the age of battery in non volatile memory since the BMS is flashed and powered with battery modules. The battery core will use this counter and run it's own algorithms to extract the best out of the battery. Also it looks like our team has overlooked the scenario of how the battery core will perform when the whole battery gets replaced. I will have to get more information from my colleagues about ageism of batteries as I didn't work on battery core part of BMS.

I got some more information how BMS acts when battery packs are replaced due to degradation or ageing.

Battery core of a BMS estimates the capacity or input resistance based upon inputs it receives from cells and keeps updating non volatile memory to understand how much it has aged. Suppose a battery pack is changed in BMS, the core algorithm is smart enough to self realise that a pack is new when it sees a significant change in resistance of the pack. Other approach is BMS has information for storing the history of replacement, status of battery when it was installed and date at which it was integrated in car. All this is done at end of line. When a new battery pack is installed, the BMS realises that it is new pack from it's historic data and core algorithm recalibrates itself.

[volkman10]

Fast Charging Vs. Slow Charging: Study reveals difference in range degradation.

Recurrent Auto analyzed the data from over 12,500 Tesla vehicles in the United States.

analyzed charging data from over 12,500 Tesla vehicles in the United States, the rate of range degradation is statistically similar when compared to AC charging.

compared cars that fast charge at least 90 percent of the time to cars that fast charge less than 10 percent of the time, and the results show little to no difference between the two charging methods.

Choosing between DC over AC isn’t the only thing that can affect the battery in the long run, with factors such as extreme temperatures and very low or very high states of charge also playing a big role in the big scheme of things.

To help the battery last as long as possible, using the preconditioning feature is of utmost importance, both in extreme heat and in extreme cold, as this brings the cells to the optimal temperature before plugging in the charging connector. Another tip is to avoid fast charging at very low states or very high states of charge, as battery resistance is higher at these levels and puts additional stress on the battery.

Another study from 2020 found that battery-powered vehicles, including EVs and PHEVs, encountered battery degradation anywhere from zero percent to 4.1 percent in the first year

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