BQ40Z50-R2: About Sleep Balance

Hi Ian,

lan xin said:

Hi，I want to configure the sleep balancing function of BQ40Z50-R2. If the battery RSOC>60% after 24 hours of sleep, I need to use this function to balance the RSOC to 60%. Attached is my configuration file. Please check if there are any parameters set incorrectly?

I am confused on what is meant here, if the RSOC is greater than 60% for over 24 hours, you want the gauge to bring the RSOC back to 60%? I believe this would need to be done by discharging to that percent. The purpose of the cell balancing functionality is to ensure the cell voltages are the same through using bypass FETs. 

lan xin said:

SMBus low for Bus Timeout(1) if [IN_SYSTEM_SLEEP] = 0, or no communication for Bus Timeout if [IN_SYSTEM_SLEEP] = 1
The above description states that my [IN_SYSTEM_SLEEP]=1, regardless of whether the SMBus is pulled down or not, as long as communication is stopped, can I enter sleep mode?

You are correct here.

Regards,

Anthony

Hi，As shown in the red box in the following figure,

I understand that in sleep mode, after meeting the sleep balance conditions, the battery can be balanced to the end of Rsoc for Bal in Sleep (60%). Or maybe I misunderstood, this means that the voltage difference between the cells will be balanced during the sleep process, rather than discharging the electricity to the End Rsoc for Bal in Sleep (60%) through balancing. Which understanding is correct? Or could you help me explain the operational logic of sleep balance? Thank you

Hi Ian,

Sorry for the confusion, I believe your understanding is correct here. The End RSOC for Bal in Sleep here would need to be set to 60% and Start Time for Bal in Sleep should be 24 hours, however I believe we might need to change the Start RSOC for Bal in Sleep to a value slightly higher than 60%. I believe if both thresholds are 60% once the balancing has ended, there could be some sort of confusion if there is any recovery.

Regards,

Anthony