BQ4050: Charge Loss Compensation

Hi Amit,

More information about how the charge loss compensation parameters work can be found below:

This information is in the Advanced Charge Algorithm document found here:

https://www.ti.com/lit/pdf/slua875 

Regards,

Anthony Baldino

Thank you for the response Anthony

Can you explain the terms CCC current threshold and CCC voltage threshold. As per my knowledge CCC voltage threshold is max cell voltage (in case of Li-Ion, 4.2V) and based on the document you have provided I think CCC current threshold is IR compensated charging current (for example if charging current is set to 4A and the charging current is 3.57A then 3.57A is IR compensated charging current). 

I maybe wrong do correct me

Regards

Amit

Hi Amit,

I believe you are correct for the CCC voltage threshold, which should be set to the max cell voltage. Regarding the CCC Current Threshold, I believe that this should be set to the IR compensated charging current and that your process is also correct since the charge loss compensation conditions follow suit.

Regards,

Anthony Baldino

Hi Anthony,

I came across this thread which explained about CCC voltage threshold. However I'm not clear on the behavior of CCC current threshold. I came across another thread regarding current threshold. But, I was unable to understand the value 4200mV set, which parameter is this 4200mV which gets set when the charging current is less than current threshold? 

Regards,

Amit 

Hi Amit,

I believe in the second thread you are referring to, they are showing that the CCC Voltage Threshold is the voltage that the charge will increase too if there is a detected drop in the current, shown by the current dropping lower then the CCC Current Threshold. In the TRM, the 4200mV value is the default value for the CCC Voltage Threshold. The 4100mV value they reference in that thread is their standard charging voltage when there is no detected drop in the current.

Regards,

Anthony Baldino

Hello Anthony,

I'm actually not convinced. The two threads I have mentioned in the above reply Charging loss compensation: ccc voltage threshold, Charging loss compensation and the assumption that 4200mV being set in the second thread is CCC voltage threshold, everything is not syncing together. The explanation of CCC Voltage threshold in both the threads are different, consequently making explanation of CCC current threshold difficult to understand. Can you give a detailed big picture.

Regards

Amit

Hi Amit,

After rereading both of the past threads, I believe there was a misunderstanding here where it is stated:

"The rec temp charging in advanced charge algorithm is set to a voltage of 4100mV and 3520mA. If the current drops to a value below this at the range, the voltage request to the charger will be set to 4200mV. A boost in voltage is requested to increase current. This will be done by the gauge instead of the host having to query voltage and current and increasing them if needed."

I believe their understanding of the 4200mV default is off. Based on the conditional statement seen above, the ChargingVoltage is not changed directly to the CCC Voltage Threshold, but the Charging Algorithm Voltage + CCC Voltage Threshold. I do not believe this should be changed to the maximum cell voltage value, but the charging algorithm voltage + CCC Voltage Threshold should equal the maximum cell voltage at that time.

While in the Active state, where the current is greater then the CCC Current threshold, the Charging Voltage will be Charging Algorithm + (PackVoltage - Voltage). I believe that the CCC Voltage Threshold is supposed to represent the maximum difference between the Pack Voltage and the Voltage that the gauge will want to represent, since if these values continue to grow more different, it could increase the charging voltage to an unsafe value.

Regards,

Anthony Baldino

Hello Anthony,

I'm still not convinced with the above reply. According to the table below

The case what you are explaining is Limiting Status where there is no condition of CCC current threshold. In Normal and Active status where there is CCC Current threshold condition there is no presence of CCC Voltage threshold, both are independent parameters as per the table.