FCC's value and the Remain capacity reduce more than 40mAh in the OCC Protect test some times...Why does the fcc vary so much....
What OCC Protection test does is to force the Impedance Track (IT) devices out of rest mode. When the IT devices exit rest mode, new FCC and RemCap are being calculated.
The IT devices constantly learn (measure and update) battery cell impedance during discharge. When the battery is resting, the IT devices transition from Coulomb Counting mode to Voltage mode. When the pack exits rest mode, such as when discharge starts, it transitions to coulomb counting mode again. During this transition, it simulates a voltage discharge profile and finds the FCC and Remaining Capacity using the impedance table measured from the last discharge cycle, as well as using a thermal profile predicted based on the current ambient temperature and a complex thermal model. Because of all these variable parameters, the new FCC and RemCap may not be the same as the one learned from the last discharge cycle. Therefore, the jump in FCC and RemCap is to ensure a closest prediction of capacity and runtime.
In fact, 40mAh is not a big difference. It's 1% for a 4000 mAh pack.
Thanks for your quickly reply....
However my design capacity is 2200mAh...
The FCC and RC can return to a normal value (similar to the previous value) ..if i apply a 0.5C(not critical ) discharge to the pack ....
A most serious test, the fcc jump from 2150mAh to 1873mAh. It return to the privious value when applied 0.5C discharged current.
The Over current test poses a higher load than normal, and the algorithm may be using this load to calculate the remaining capacity. If load increases, the IR drop is higher, and the resulting usable capacit (= FCC) is smaller. What is your DF:Load Select setting?
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