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Original question:

BQ79606A-Q1: Will OV/UV monitoring continue from where it was if cell balancing is paused.

BQ79606A-Q1: Cell balancing using bqStudio

Bing Han Char
Prodigy 10 points
Part Number: BQ79606A-Q1

Hi TI Team,

Lately I've designed a board referring to the Eva board and right now I'm testing out the cell balancing features.

The data obtained using the cell voltage monitor after enable cell balancing and my configuration for cell balancing is as below.

My questions are

  1. The cell balancing features seems like working well but why is the cell not able to balance up in the end. Is there any problem with my configuration setting?
  2. I even tried to set 120minutes balance time for cell2,3,4,5 and 0 minutes balance time for cell1,6 but the voltage of each cell still didn't balance up.

I'm charging my 18650 cells using DC power supply with output setting 25.2V and 2A.

  • 0
    TI__Genius 17440 points

    Hi Bing,

    Can you clarify if you are disabling the charging when you are balancing? Typically the cell balancing would not happen at the same time as the charging. Also, what is the cell balancing current on your board?

    Best Regards,

    Kristin Jones

  • 0 in reply to Kristin Jones93
    Prodigy 10 points

    Hi Kristin,

    I didn't disable the charging when I'm balancing the cells.

    The cell balancing current I set is 138.6mA as the V(bat)=4.2V(which is maximum voltage for a single cell); R(eq)=12ohm

  • 0 in reply to Kristin Jones93
    Prodigy 10 points

    For my understanding, when I enable the cell balancing features while charging my cells, the resistor with active cell balance will draw the current and dissipate it as heat which able to help reduce the current intake for that particular cell.

    In the same time, the other cell without active cell balancing will slowly charge up.

    Is my understanding correct?

  • 0 in reply to Bing Han Char
    TI__Genius 17440 points

    Hi Bing,

    In theory this could work, but in the graph you shared it looks like this approach will take much longer to even the cell charges than the time you previously ran it. You could continue this method for a longer period and see if the cells get closer to balanced. The balancing FETs do look like they're working, based on the toggling cell voltages. My concern with this method is that some cells that may have a smaller capacity will never catch up to the other cells. 

    Best Regards,