Dear All,
One of our customer using BQ34Z110 chip, they have manufactured about 80 boards and facing issues with 2 units. Two Chips are reading the Current incorrectly. customer analysis as below, please help to advise to resolve the issue.(Please visit the site to view this file)(Please visit the site to view this file)(Please visit the site to view this file)(Please visit the site to view this file)
1) Capacity estimation shown by 2 units (gas gauge) was wrong .
2) Battery voltage was 12V , GG showed 100 %.
3) Replaced the battery of the two units, problem again appeared.
4) During Charge and Discharge cycle, the current measured by gas gauge shown a difference of 50 mA with the actual value.
5) After calibrating current, for an actual current of 0mA gas gauge showed 52mA.
The schematic and battery charging cycle details of failed unit is attached along with this.
Also GG file of one working unit and faulty unit attached along with this
battery charge/discharge cycle test log also attached.
The second experiment ( battery Charge and Discharge cycle) . I am attaching the log data along with this.
The experiment details are below.
1) A fully discharged battery is connected to the EUT.
2) Enabled the charger ( on15/07/16 @ 10.41am).
3) Disabled the Charger ( on 16/07/16 @ 06.40am).
4) Kept the battery to relax for 3 hrs.
5) Enabled the discharge cycle to a resistive load @510mA (multi-meter reading on 16/07/16, 10:09am).
6) Disabled the discharge cycle when battery voltage reached 10V( @ 16/07/16,18:15).
7) Kept the battery to relax.
Observations During experiment:
1) During current calibration, an offset current of 47mA is observed in the gas gauge reading.
2) During discharging also an Offset between 40 to 50mA observed.
3) During discharging, SOC automatically bounced back to 88% from 70 %, Current doesn't changed.
4) During discharging when the battery voltage crossed 11.3V , the SOC was 51%.
5) 11.3V is the actual cut in voltage of our unit. If the above observation(4) is there the unit will switch OFF without low battery indication
Aravind.
