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BQ27541 Learning Cycle

Leonard Urbanovsky
Prodigy 30 points
Other Parts Discussed in Thread: BQ27541

I am using a BQ27541 to gauge a 3S6P Lithium-ion battery pack. How important is it to charge the pack at a C/2 rate during the learning cycle? In my application the pack is charged at a 1A rate max. I would like to use the charger circuit for my application to charge the pack during the learning cycle.

 

Leonard

 

 

  • 0
    TI__Genius 14985 points

    It will probably be okay to use 1A for charging.  If you get Update Statue = 05 after the relax/charge/relax portion of your learning cycle, then you know it was fine.

    Then you must discharge at ~C/10 and relax to get Update Status = 06 and you know the whole learning cycle was successful.

    Worst case, you could also do the learning cycle on a 1S1P cell then scale everything by six.

  • 0
    Prodigy 170 points

    Not to post what may be a somewhat obvious answer, but ...

    Anything involving learning should be kept as close to the specifications as possible.  Once the gauge has learned about the battery its ok to modify things to some extent, but during the learning phase its important to do whatever the software says. 

    For example if the program says it wants to learn a C/2 rate of charge and you give it a C rate of charge, then the algorithm is going to think that the battery charges faster than it actually does.  Why?  Because it thought it was charging at a rate of C/2 and it was really charging at a rate of C.

    My advice is to follow the guide exactly, and then once the algorithm has been trained work with modifying the values.