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BQ27530-G1: CC Delta values

Part Number: BQ27530-G1
Other Parts Discussed in Thread: BQSTUDIO,

Hi everyone,

I'm trying to calibrate fuel gauge (BQ27530-G1), which is installed in one of our devices. I use bqStudio 1.3.86 and BQ27GDK000EVM. Our device is connected to this evaluation board via I2C lines and battery leads are connected to EXT_Load- (J8) and EXT_Load+ (J4) connectors. When I calibrate the current measurements for several devices, bqStudio calculates the values of CC Gain and CC Delta around 2 mOhm on average.

However, when I try to enter these values in the Data Memory of other devices, bqStudio throws out the error: "Value is beyond maximum value defined for parameter.: Calibration.Data.CC Delta".

The test current is 1A and the sense resistor value is 10 mOhm.


  • Pavels,

    bqStudio imposes limits to make sure some extreme and undesired values are not written to the gauge. You can always write the value manually using the I2C advanced comm screen using block writes directly to the address.  

    You are not saying calibration is failing, you just cant write other boards to the same value? This is not actually the way you want to do this. When you write the value using bqStudio you lose a lot of resolution. This is because the FW actually stores a really large integer to help with internal math calculations since floating point math is very expensive when talking about processing power. 

    I recommend you take a board that is successfully calibrated and returning good results, then read out the CC cal data, then write this value into other devices as needed. However, it is recommended to calibrate each board.


    Eric Vos

  • Thanks, block writes using I2C advanced communication did work, although the real problem was that I didn't calibrate the board properly. Initially, I've connected EXT_Load- (J8) connector of BQ27GDK000EVM to the negative terminal of the battery instead of the ground net of our device. After fixing this, the calibration set CC Gain and CC Delta values to approximately 10 mOhms, which corresponds to our sense resitor value.