BQ28Z610: Why does Qmax Pack equal Qmax Cells?

Vu Tran27

Part Number: BQ28Z610

Hello,

I have 2 questions regarding the Qmax after the learning cycle:

1. As in the title, I noticed that the Qmax Pack is the same as Qmax Cell 1 and 2 after the learning cycle. Isn't it should be the sum of Qmax Cell 1 & 2? Is there anything I did wrong here?

2. The Qmax Cells after the learning cycle is about 15% higher than the design capacity of the battery. Is that normal?

Thank you!

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

See my answers below.

a) QMax Pack is the QMax of the whole stack, NOT the sum of Qmax Cell 1 & 2.

b) Yes, that is normal.

Andy

0 Vu Tran27 over 5 years ago in reply to Andy Liu (BMS)

Intellectual 445 points

a/ Can you explain why the Qmax of the whole stack is different than the sum of Qmax of cell 1 & 2? Because for my case, after learning cycle, as Qmax Pack = Qmax Cell 1 = Qmax Cell 2, the StateOfHealth() = 50% for brand new battery, which is obviously wrong. I am using 2s1p battery.

0 Andy Liu (BMS) over 5 years ago in reply to Vu Tran27

TI__Guru 52115 points

Before the learning cycle, you need to set Qmax Pack, Qmax Cell 1, and Qmax Cell 2 to the design capacity multiplied by the number of parallel cells.

After the learning cycle is done, the Qmax Pack should be the smaller value of Qmax Cell 1 and Qmax Cell 2.

Andy

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BQ28Z610: Why does Qmax Pack equal Qmax Cells?