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BQ27505-J2: Impedance Track™︎ technology

Jing Huang
Prodigy 10 points
Part Number: BQ27505-J2
Other Parts Discussed in Thread: BQ27426, BQ27427

Hi team, 

I have some questions when reading  Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm (Rev. A)

1) What's the purpose of 30mins waiting time at the beginning of relaxation period? is that for voltage across capacitor in the equivalent circuit inside battery be settled down?  For high capacity battery with equivalent  higher capacitor value, should we increase 30min to even longer time? 

2)The impedance track R will be mostly used in compensating OCV - I*R in the relaxation period. Is this application mainly for phone with standby mode?  For the application with high capacity battery, when there is no current in the relaxation period, is this algorithm still a fit? 

3)What's the effect of voltage measurement noise for this algorithm? 

Thank you very much! Really appreciate your help! 

  • 0
    TI__Genius 15325 points

    Hi,

    1) To allow the battery to relax. 

    2) Yes

    3) Minor noise should not cause major problems.

    Are you sure this is the best device for this application?

    Regards,

    Evan

  • 0
    Prodigy 10 points

    Hi Evan, 

    Thank you very much for your quick response. 

    I would like to clarify that: 

    1) for higher capacity battery, we do need longer time to relax compared to 30mins? 

    2) since I have two questions in 2), not sure which one you are replying. Did you mean the algorithm application is mainly for phone with standby mode?  

  • 0 in reply to Jing Huang
    TI__Genius 15325 points

    Hi,

    1) Possibly during the learning cycle to get update status to progress. But during normal use in the field this does not need to be monitored. The gauge will detect when the battery is relaxed and gather required information while the battery is relaxed.

    2) Sorry about that, allow me to clarify. Q2-1 This is used for all applications to monitor the battery in relax mode. Q2-2 Yes.

    Are you sure a newer device like the BQ27426 or BQ27427 would not be a better fit for their application.

    Regards,

    Evan