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BQ78350-R1: the CEDV parameter in bq78350

Part Number: BQ78350-R1
Other Parts Discussed in Thread: GPCCEDV, BQ78350, BQSTUDIO

Hi team,

Here's an issue from the customer may need your help:

The description in the reprort of GPCCEDV file is as follows:

CEDV parameters resulting from the fit. If EDVV bit is set to 1, EMF and EDVR0 have to be multiplied by the number of serial cells when written to data flash.
EMF 3517
EDVC0 623
EDVC1 0
EDVR1 89
EDVR0 1375
EDVT0 5229
EDVTC 11

1. Regarding EDVV bit, it cannot be found in Battery Management Studio (bqstudio).Which status bit is referred to in the BQStudio software? Also not found in bq78350 file.

2. Also, "EMF and EDVR0 have to be multiplied by the number of serial cells when written to data flash", dose this mean the current report going to be converted as well? (This report is currently 2 strings of 1 data). If they want to change to 6 string 2, is the following parameter correct?

EMF 10551 (3517/2*6=10551)      
EDVC0 623
EDVC1 0
EDVR1 89
EDVR0 4125  (1375*6/2=4125)
EDVT0 5229
EDVTC 11

Could you help check this case? Thanks.

Best Regards,

Cherry

  • Hi Cherry,

    The EDVV bit does not apply for the BQ78350. It is used in some other gauge devices. There is no need to multiply EMF and EDVR0 for the BQ78350.

    Best regards,

    Matt

  • Hi Matt,

    There is no need to multiply EMF and EDVR0 for the BQ78350.

    Does the BQ78350 automatically compensate for conversion once the data is filled in?

    The following is the adjustment method given by the application data:

    The same cell CEDV parameters apply to different strings in parallel. When CEDV of the same cell is ready, it can be applied to the battery combination of different strings of cells with only a small adjustment. Save development time for battery development users by eliminating the need to re-run the CEDV parameter acquisition process for different battery combinations in parallel.

    The seven CEDV parameters are adjusted by:

    (1).EMF, proportional to the number of strings, such as single-cell EMF = 4000 mV, EMF = 12000 mV for 3-string 3-cell and EMF = 16000 mV for 4-string 2-cell.

    (2).EDVR0, adjusted like the equivalent of the string parallel of the resistor, for example, single cell R0=4000, then R0=4000 * 3/3=4000 for 3-string 3 and R0=4000 * 4/2=8000 for 4-string 2-cell. If the cell connection impedance is large, it is recommended to multiply the connection impedance by 4 to R0.

    (3). The remaining parameters EDVC0, EDVC1, EDVR1, EDVT0, EDVTC do not need to be modified.

    Thanks and Best Regards,

    Cherry

  • Hi Cherry,

    The BQ78350 knows the number of cells in series (from the AFE Cell Map data flash parameter). So there is no need to adjust coefficients based on the number of cells in series because the BQ78350 firmware already considers this. 

    The only parameter that needs to be adjusted if adding cells in parallel is EDVR0. R0 should be divided by the total number of parallel cells (if the data collected for the GPCCEDV tool was from a battery with only one cell in parallel).

    Best regards,

    Matt