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BQ27Z746EVM-047: The fuel gauge cannot charge or discharge, and the battery current read by the fuel gauge is 0 (first use of BQ27Z746EVM).

Shu Simo
Prodigy 10 points
Part Number: BQ27Z746EVM-047
Other Parts Discussed in Thread: BQ27Z746, BQ27Z758

1.Hardware connection environment for charging function test

Charging hardware connections: The BAT+/BAT- of the BQ27Z746 EVM are connected to the VBAT+/VBAT- of the battery; the Pack+/Pack- of the BQ27Z746 EVM are connected to the BAT+/BAT- of the charger IC; the SDA/SCL of the BQ27Z746 EVM are connected to the pins of the STM32G071 development board; the enable pin of the BQ27Z746 EVM is connected to GND.
 
Issue and phenomenon: The charger IC enables charging and supplies 5V power. The measured BAT+/BAT- voltage of the charger IC is 4.4V, but the battery cannot be charged. The following is the printout of the read register information:

[DEBUG]bq27z758 get battery status: 0xc0                             <---- The battery is discharging.
[DEBUG]bq27z758 get VoltLoSetThreshold: 0x9c4 
[DEBUG]bq27z758 get control status: 0x20c 
[DEBUG]Relative State of Charge : 51 %
[DEBUG]Temperature : 301.7 K

[DEBUG]Relative State of Charge : 51 %
[DEBUG]Voltage : 3851 mV
[DEBUG]Current : 0 mA
[DEBUG]Charging Voltage : 0 mV
[DEBUG]Charging Current : 0 mA
[DEBUG]Full Charge Capacity : 5305 mAh
[DEBUG]State of Health : 99 %
[DEBUG]Temperature : 301.4 K

[20:55:52.801]status data read:
[20:55:52.842][DEBUG]PFSTATUS A+B:0000 PFSTATUS C+D:0000
[DEBUG]PFALERT A+B:0000 PFALERT C+D:0000
[DEBUG]OPERATIONSTATUSA:E100 OPERATIONSTATUSB C+D:0040       <----  SLEEP mode conditions met, Charging disabled,  Discharging disabled, SECURITY mode Full Access, CHG FET status Inactive, DSG FET status Inactive, 400-kHz mode Active
[DEBUG]CHARGINGSTATUS:000410    <---- Charge inhibit Active
[DEBUG]GAUGINGSTATUS:04400028     <---- Termination voltage reached during discharge, Terminate charge Detected
[DEBUG]MANUFACTURINGSTATUS:8000     <---- CALIBRATION mode Enabled, FET_EN=0, GAUGE_EN=0, DSG_TEST=0, CHG_TEST=0

 

2.Hardware connection environment for discharge function test

Discharge hardware connections: The BAT+/BAT- of the BQ27Z746 EVM are connected to the VBAT+/VBAT- of the battery; the Pack+/Pack- of the BQ27Z746 EVM are connected to the Input+/Input- of the electronic load.
 
Issue and phenomenon: The electronic load is set to a constant current load of 200mA, but the battery does not discharge. The measured Pack+/Pack- voltage of the BQ27Z746 EVM is 0V.
 
Could you please help analyze what the problem is? Thank you!