We have received inquiries about cycle count in the battery product group to which the BQ27542 is applied, so we are inquiring.
The response received after contacting TI regarding the Cycle Count in Gauge IC before (2017) is as follows.
-------------------------------------------------------------------
(TI reply)
1. [TI] bq27542 has CycleCount(0x2A, 0x2B) register which represents number of cycling and it is based on ‘passed charge’ including not only passed current in charging but passed current in discharging mode. It doesn't requires full charge or full discharge.
2. CycleCount() works based on accumulated current including both directions in charge and discharge. Basically it count up when ‘passed charge’ reaches at two times of Design Capacity(threshold is configurable), which means it still count even under partial charge/discharge case. In short, customer doesn’t need to worry about Cyclecount because it works properly at any use cases.
3. In the case of “One cycle occurs when accumulated discharge >= CC Threshold” described in the datasheet, the explanation is the same as the passed charge explained above.
In the case of Passed charge, since both directions of charge/discharge are checked, the CC Threshold (= design capacity %) is set twice, whereas in the case of Accumulated discharge, only discharge is considered, so the standard of CC Threshold (= design capacity %) will increase the cycle count.
-------------------------------------------------------------------
Additional inquiries occurred and as a result of additionally checking the Datasheet (TRM), it was confirmed that it was stated as follows.
6.1.1.2 Cycle Count records the number of cycles the battery has experienced.
One cycle occurs when accumulated discharge ≥ CC Threshold.
The value is reported in CycleCount().
6.1.1.3 Cycle Count Threshold
This value increments CycleCount(). When the gauge accumulates enough discharge capacity equal to CC Threshold, then it increments CycleCount() by 1.
This discharge capacity does not have to be consecutive.
The internal register that accumulates the discharge is not cleared at any time except when the internal accumulating register equals the CC Threshold, and increments CycleCount().
This is normally set to about 90% of the Design Capacity.
Looking at the above, it is said that the Cycle Count is increased after 90% (CC Threshold) of the Design Capacity is discharged, and in the case of Passed charge, it is said that the CC Threshold x 2 is set, but this part is not even on the datasheet. , I don't understand exactly.
Please provide further explanation regarding this matter.
1. Difference between Passed charge and Accumulated discharge.
2. Differences when the design in the actual Gauge IC is as follows.
EX) Design Capacity: 2900mA, CC Threshold: 2610mA
A. In case of Passed Charge:
B. In case of Accumulated Discharge:
Please check. Thank you.
