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bq40z60 - Not charging - what is wrong?

Fred Arnold
Intellectual 680 points
Other Parts Discussed in Thread: BQSTUDIO

Hi,

I am using the bq40z60EVM and bqStudio to get an initial working configuration but it refuses to charge.

I set the NR flag as the battery is not removable and also the number of cells to 2.
I also use Precharge and configured it accordingly.
Charging Voltages and currents have been also set if I did not miss anything.

I am using 2 IMR cells with the following specs:

Max charge Voltage 4200mV +/-50mV
Nominal Voltage 3700mV
Typical capacity 1100mAh
Impedance 15mR
Min discharge voltage 3000mV
Typ charging current 1100mA (8 hours)
Max discharging current 22A
Charging temp 0 to 45 degC
Discharging Temp -20 to 60 degC

I would be happy if someone could help me with setting the design up so it initially works.

I do not have a chemistry ID for these cells which I would need to determine afterwards as well.

I have attached the exported .gg file with my current settings.


Thanks,
Fred

bqStudio.gg.zip

  • 0
    TI__Guru 73830 points

    I can see a few problems with the parameter setup.

    • The FETs and Charger are not enabled. (You need to press the GAUGE_EN, FET_EN and CHARGER_EN buttons.)
    • The Minimum Voltage Output is set to 8400mV. This should set to the low end of the charging voltage range. e.g. 4214 for a 2S pack. The Voltage resolution should be set to 16.
    • The Precharge Start Voltage should be set at the cell level. e.g. about 2500mV.
    • The Charging Voltage Low is set too high. should be about 2900mV.

  • 0 in reply to ThomasCosby
    Intellectual 680 points

    Thanks Tom!

    Charging works after I made those changes.

    Now I got a problem with discharging the batteries. The FETs turn off as soon as I reach -4000mA discharging current with the AC adapter power turned off. After I reduce the load current slightly, the FETs turn on again after ~15s.
    I can't see a fault. OCD1 and OCD2 are set to -12000mA at a recovery time of 3s.

    I attached the Data Memory content and Flash image. Perhaps you can tell me what is limiting the discharge current.

    Thanks again,
    Fred

    bqStudio_Config.zip

  • 0 in reply to Fred Arnold
    TI__Guru 73830 points
    Fred
    I do not see anything in the gg file that would cause the discharge current to be limited to 4A. The 15s recovery time make it look like an AOLD or ASCD fault. Are you sure that these flags are not getting triggered?

    Tom
  • 0 in reply to ThomasCosby
    Intellectual 680 points
    Thanks for your help Tom.
    It was the AOLD limit.
    I increased it to 12A and now it does not turn off anymore.