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BQ27542-G1: SOC jump

rock shen
Intellectual 585 points
Part Number: BQ27542-G1


Hi,Sir:

      We had found a strange phenomenon,

when we use a DC source to make a fake battery with BQ27542-G1 IC,

the voltage we set as 4.2V,we power on our device and run a loading,

the SOC will reduce from 99% to 1% step by step, and keep on 1%;

but when we use an adapter output with 4.2V to instead of the DC source to make a fake battery,

we power on our device and run a loading with same condition as above experiment set,

the SOC will reduce from 99% to 16%, and jump to 99% again,

from my point, both adapter and DC source power the power,

the current no limit, no OCP issue,

it should be same result for the SOC change,

but it different.

Why the phenomenon happen between adapter and DC source?

the Gauge IC BQ27542-G1 had difference setting for the adapter and DC source?

If so,what is the difference setting between adapter and DC source?

and how Gauge IC BQ27542-G1 to detect an adapter and DC source?

Thanks!

  • 0
    TI__Guru* 76230 points
    Hi Rock
    The difference would be in the internal impedance of both. Note that this gauge is tracks the internal impedance of the battery which in this case is your power supply and adapter.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Intellectual 585 points
    Hi,Sir:
    So you mean the adapter's internal impedance is more smaller than the battery define,
    when a battery SOC calibration time,
    the SOC jump to 99%?
    If so, I think the SOC of battery that power supply by adapter should not drop to so lower,
    Do you think so?
    Could you kindly help to do experimence and check the phenmenon,
    and check why it happen?
    Thanks!
  • 0 in reply to rock shen
    TI__Guru* 76230 points
    You can't use an adapter or power supply to sufficiently mimic a battery and the gauge performance because the voltage doesn't continuously decrement like a battery would. Using a power supply is basically to just test functionality . To evaluate SOC use a battery with load


    thanks
    Onyx