Other Parts Discussed in Thread: BQSTUDIO
Hi,
I have a power section which is using BQ27441 as the fuel gauge to measure the status of a LiPo battery that has 4400 mAh capacity in total. The 4400 mAh capacity is achieved by connecting two identical 2200 mAh batteries in parallel. By the datasheet of the battery, the Maximum voltage is about 4.2V, the nominal voltage is 3.7V and the discharge cutoff voltage is 2.7V. The system parameters are listed below:
Maximum charging current: 2.4A
Maximum discharge current: 2A
Minimum running voltage: 3.4V
Maximum battery voltage: 4.2V
Cutoff current: 160 mA
the current sense resistor is 10 mOhm
For this system we configured the following parameters in the fuel guage:
BATTERY_CAPACITY = 4400 //4400 mAh battery will be connected
TERMINATE_VOLTAGE = 3400 // 3400mV terminate voltage
DESIGN_ENERGY = 16280 //16280 mWh design energy
TAPER_RATE =275
FC set = 92% full charge set
FC clear = 90% full charge clear
TAPER_VOLTAGE =4160
Fortunately, the fuel gauge is measuring battery voltage and temperature at much better accuracy but it is not for average current and capacity. I am listing my issues and questions below:
Issue 1:
The current (Both Discharging and charging) measured by the fuel gauge having an error of more than 8% (more than 200 mA). Same for the remaining capacity and percentage of charge remaining also.
Issue 2:
The fuel gauge is showing 100 % of charge while charging even it is only at 3881 mAh and 0% before it is reaching the Terminate voltage (3.4V)
Question1:
I need to measure the current and capacity of the battery with much accuracy(less 1% error), so I have gone through different documentation and Questions about BQ27441, and got to know that the IC will do auto-calibration for CC_Offset, but I should do the learning, calibration, Chem_ID creation and golden file creation manually. Unfortunately, I couldn't find the proper flow for doing this, that is which one should do first and which should be last (for learning, calibration, Chem_ID creation and making golden file ). So could you please tell me the steps by step procedure for rectifying the accuracy issue without bqStudio?
Question2:
Why the fuel gauge is showing 100% and 0% before it is even be reached? how can we rectify that?
