Dear All,
I use bq78z100 fuel gauge IC in my battery pack. According to my investigations, There is FCC(Full Charge Capacity) calculation failure in bq78z100 fuel gauge IC and the issue is caused by SHA-1 Authentication requests during the operation. When the failure is occured, the capacity of the battery seen as very low (from 3000 mAh to 300mAh or 0 mAh). After that, the battery can not charged or runs out quickly.
Actually the IC naturally updates FCC based on following conditions(from your datasheet):
• QMax update occurs
• Ra update occurs
• At onset of charge and discharge (RSOC = %0 & %100, FC = charging/full)
• At exit of discharge
• Every 5 hours in RELAX mode
• If temperature changes more than 5°C
However, when any of the above conditions are appeared, If you use frequent SHA-1 Authentication, it corrupts FCC calculations. By the way, RSOC is also damaged as well.
Users generally desires to use SHA-1 Authentication to protect their device during the operation and they may want to activate the authentication function for all time. So, you should consider this use case and provide a solution in your product. Authentication should be performed in parallel without affecting any other fuctions.
Could you please take the issue into consideration and provide a solution?
Best Regards
