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BQ20Z95: Fast Charge current and first and second level safety current settings

Hans Donovan52
Prodigy 10 points

Part Number: BQ20Z95

In my system if the Fast Charge Current (C431 in the TRM) is set higher than the first (C221) or second level safety current (, the battery doesn't charge.  A TCA (terminate charge alarm) is set on the SMBUS.  If the FCC is set lower, the operation is normal.

We receive the batteries from a battery manufacturer programmed with FCC set higher.  I was hoping they knew what they were doing.

Should the first and second level safety current be set higher than the fast charge current?

  • 0
    TI__Expert 4065 points
    Hi Hans and sorry for the late response, first and second current safety levels should not be set higher than fast charging current since you will be losing this 2 level safety feature.
    Best,
    Haidar
  • 0 in reply to Haidar Hamoo
    Prodigy 60 points
    Hi Haidar,
    I have a similar question on the same battery. If my FCC is set to 2000 mA and my 1rst level safety current is set to 1630 mA. One battery will never charge at 2A but will continuously try to reach that level and then fall to zero.
    Why is FCC set at 2000 and not 1500?

    Thanks,
    Alan
  • 0 in reply to Haidar Hamoo
    Prodigy 60 points

    If on this same battery the first level safety feature is set to 1630 mA why is the fast charge current set to 2000 if the battery can't charge past 1630?

  • 0 in reply to alan lichliter
    TI__Expert 4065 points
    Hi Alan,
    Just to clarify, FCC setting is either in (mAh) or (10mWh) and not in (mA) since FCC is a capacity not a current, your OCC and OCD 1st and second safety are current thresholds set according to your battery datasheet max. charger and discharge current.
    Best,
    Haidar
  • 0 in reply to Haidar Hamoo
    Prodigy 60 points

    Haidar,

    Thanks for your prompt reply.

    I still am a bit confused because C4.3.1 says mA  as units.

    Name Value Unit Paragraph Min  Max Default
    Fast Charge Current 2000 mA C.4.3.1 0 10000 4000

    Sincerely ,

    Alan

  • 0 in reply to alan lichliter
    TI__Expert 4065 points

    Hi Alan,

    I was referring to Full Charge Capacity (FCC) and not Fast Charging Configuration (FC cfg) just to clarify,  now I see your point, since you got your batteries from the manufacturer set with these 1st & 2nd safety current threshold, yes I would lower your Fast Charging Current setting to be lower than the 1st safety current threshold so as not to get [TCA] alarm and then [TC] Status after timer for [TCA] expires and then charging will stop. I would recommend checking with the battery manufacturer about this issue since if you lowered the Fast Charging Current setting, the battery will take a relatively longer time to charge.

    Regards,

    Haidar  

  • 0 in reply to Haidar Hamoo
    Prodigy 60 points

    Haidar,

    Again thanks for your quick reply.

    This information is very helpful. We will contact the manufacturer.

    Regards,

    Alan