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BQ40Z50-R3-DEVICE-FW: Impedance track algorithm support

Ke Chiachou
Prodigy 20 points

Part Number: BQ40Z50-R3-DEVICE-FW

Hello TI partners,

Now, cell supplier would like to enhance safety perforemance.

However, this change will cause cell impedance increase in fresh and ageing status.

I worry about this symptom impact to impedance track setting and capacity accuracy.

Please support to clarify as below questions:

1. For fresh cell/ pack, is there any definition for impedance tolerance? (Ex: Tolerance over 3% between Chem ID & cell that will affect accuracy)

2. If cell characteristic has gap with Chem ID, how many percentage (max) can compensate by impedance track algorithm?

Thank you so much.

  • 0
    TI__Guru** 105760 points

    Hello Ke,

    If you change packs you should find the new chem ID using gpcchem tool and re-run the learning cycle.

    If you put in a new pack that was the same as the previous you should just re-flash your golden image file to the gauge (that has the learning cycle and onfiguration)

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hello Wyatt,

    If cell impedance characteristics change can be compensate, we can leverage original Chem ID with new cell. 

    So, I want to confirm how much characteristics gap can accept by currently impedance track algorithm.

    Could you share suggestion to me?

    Note:

    For cell safety enhancement, the insulation method has been changed (New Cell).

    This change cuase cell impedance characteristics change, but others like capacity/ voltage are same with original. 

    Thank you so much.

    Yours truly,

  • 0 in reply to Ke Chiachou
    TI__Guru** 105760 points

    Hello Ke,

    If your resistances have changed with the new pack, then you should use the same chemID but re-run the learning cycle so the gauge learns the new resistance values.

    You only need a new chemistry ID if the actual cell has changed, if it's only the connections that affect the resistance then you should just re-run learning cycle.

    Sincerely,

    Wyatt Keller