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BQ35100: Remaining Capacity calculation in Accumulation mode

Part Number: BQ35100

Hi,

          I'm using Bq35100 for gauging my Lithium Thionyl Chloride chemistry cell. I need to know the charge of the cell. I've put the gauge in accumulation mode.

Now these are the steps I've done.

  • Change gauge to accumulation mode
  • sent GAUGE_START command 
  • Read AccumulatedCapacity (4 bytes from 0x02-0x05
  • sent GAUGE_STOP command
  • Again read AccumulatedCapacity

Based on my understanding ,

                                    SOC = (Rem cap / Design capacity) * 100%

                    where,     Rem cap = Design capacity - Accumulated passed charge.

 

Is it correct that the accumulated passed charge mentioned here is the accumulated capacity of 4 bytes read from the gauge.

Now the values i got for my 17Ah cell is   

                                                    After GAUGE_START  -  D0 FA FF FF 

                                                    After GAUGE_STOP    -  BF FA FF FF 

How am i supposed to calculate the battery percentage using this data...Is there any additional steps I need to follow ?...

Is the charge accumulation here represents the accumulated passed charge ,which could be deducted from the design capacity??

Thank you in advance,

Arun Babu S

  • Hi Arun Babu S,

    The formula you showed is a high-level formula so you will not be able to plug numbers in to calculate the exact number. However, AccumlatedCapacity is Accumulated Passed Charge.

    SOH will report a battery percentage.

    Regards,

    Evan