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BQ27510-G2 Bqeasy battery cell characteristics

Yunfa Yang
Intellectual 515 points
Other Parts Discussed in Thread: BQ27510-G2, BQ27510-G3

Hello,


Question 1:

Minimum rated cell voltage is required by bqEasy, but my cell datasheet only gives nominal voltage (3.7V), can I use the nominal voltage as minimum cell voltage?

Question 2:

After battery was fully charged (100% fuel gauge), load test behavior was strange, capacity down to 75% immediately, discharging from 75% to 0% was close to calculated time. could it be caused by battery cell characteristics setting? if so what parameter could cause this behavior?


Question 3:

In my other post, I asked how bq27510-g2 indicates SOH, I could not find any key word about SOH in its datasheet, could you please also advise SOH implementation by using 27510?

Best regards,

Yunfa Yang

  • 0
    Intellectual 515 points

    Question 4: Must the calibration and learning cycle be applied to every single battery pack, or is once for each model good enough?

    Question 5: for learning cycle, are the time constraints of 5 hours after empty and 2 hours after full the minimum time or exact time?

    Thanks,

    Yunfa

  • 0 in reply to Yunfa Yang
    TI__Expert 4115 points

    Hello Yunfa,

    1. Yes, you should use the nominal voltage specified by the battery manufacturer.
    2. Can you provide a gauge DataRAM (i.e. Standard Commands) of this event?  Seeing what the registers are reporting when this event happens would be beneficial.   From question 1, I take it that you have walked through bqEASY, so you have done basic configuration of the gauge (i.e. Design Capacity, Design Energy, etc.), correct?
    3. The bq27510-G2 which is FW v 1.23 does not have SOH, if you want SOH then you should upgrade to ‘510-G3 FW v 4.00 (www.ti.com/product/bq27510-g3).
    4. You only need to complete the learning cycle with a single battery pack.  For calibration, we recommend taking 20 – 30 system boards and completing calibration with each board.  Then, take the average and use those calibration values in the final production (i.e. golden) image.
    5. The relaxation times of 5 hours after full discharge and 2 hours after full charge are recommendations and not min/max values.  The most efficient want to get through the learning cycle relaxation times is to monitor the [VOK] & [RUP_DIS] bits.  When those bits clear the gauge is indicating it has taken a qualified OCV reading.  Note that once the [RUP_DIS] bit clears, it should not set again throughout the remainder of the learning cycle.  I have attached a document that describes the learning cycle in more detail.

    5635.LearningCycleOverview_bq275xx.pdf

    I hope this helps.