SLUUB65B May 2015 – December 2022
This data is automatically updated during device operation. Do not make changes except for reading the values from another pre-learned pack for creating Golden Image Files. Profiles have format Cell0 R_a M where M is the number indicating the state of charge to which the value corresponds.
Cell0 R_a flag
xCell0 R_a flag
Each subclass (R_a0 and R_a0x) in the Ra Table class is a separate profile of resistance values normalized at 0 degrees for the cell in a design. The cell has two profiles. They are denoted by the x or absence of the x at the end of the subclass title:
R_a0 or R_a0x.
The purpose for two profiles for the cell is to ensure that at any given time at least one profile is enabled and is being used while attempts can be made to update the alternate profile without interference. Having two profiles also helps reduce stress on the flash memory. At the beginning of each of the two subclasses (profiles) is a flag called Cell0 R_a flag or xCell0 R_a flag. This flag is a status flag that indicates the validity of the table data associated with this flag and whether this particular table is enabled or disabled.
Each flag has two bytes:
This data is used by the fuel gauge to determine which tables need updating and which tables are being used for the Impedance Track algorithm.
This data is used by the Impedance Track algorithm. The only reason this data is displayed and accessible is to allow the resistance data on golden image files to be updated. This description of the xCell0 R_a flags are intended for information purposes only. It is not intended to give a detailed functional description for the resistance algorithms.
Cell0 R_a0 – Cell0 R_a14,
xCell0 R_a0 – xCell0 R_a14,
The Ra Table class has 15 values for each R_a subclass. Each of these values represents a resistance value normalized at 0°C for the associated Qmax Pack-based SOC grid point as found by the following rules:
For Cell0 R_aM where:
This gives a profile of resistance throughout the entire SOC profile of the battery cells concentrating more on the values closer to 0% where resistance quickly increases.
SOC, as stated in this description is based on Qmax Pack. It is not derived as a function of SOC. These resistance profiles are used by the fuel gauge for the Impedance Track algorithm. The only reason this data is displayed and accessible is to allow the resistance data on golden image files to be updated. This resistance profile description is for information purposes only. It is not intended to give a detailed functional description for the resistance algorithms. It is important to note that this data is in mΩ units and is normalized to 25°C. The following are useful observations to note with this data throughout the application development cycle:
Watch for smooth consistent transitions from one profile grid point value to the next throughout each profile. As the fuel gauge does resistance profile updates, these values should be roughly consistent from one learned update to another without huge jumps in consecutive grid points.