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Original question:

BQ24610: can't go in charge

BQ24610: Could i charge more when BQ24610 think battery is full,but the fact is just about 92% full.

Chen Yuan
Prodigy 110 points
Part Number: BQ24610
Other Parts Discussed in Thread: BQ25890

Hi,

if charge battery is not full, i hope battery could up to 96~97% full.

Not just 92% full,

but BQ24610 is not only from 92% nearly full and really slowly charging ,but also stop at 92.5%,

is this correct?

Q1: How could i cheat BQ24610 for charging up to 96~97%(the new battery could arive really)

,and how could i let nearly full charge time be not so long,

i hope if fast charge state current is limit at 2A, and i think nearly full state current should be 0.2A,

but the truth is every 1mA by charing every two minute.

Q2: Could i let BQ24610 be more fast when nearly full?

--------------------------------------------------------------------------------------------------------------------------

Circuit is all the same with the application of datasheet .

Below is what i had tried and detected:

1. i have change from R1 100K to 91k , but STAT1,2 change to high and high, that mean i can't cheat BQ24610 with Vfb.

2. R2 from 500k to 560k , the same result above.

If i could't cheat with Vfb,what other way could i try?

 

  • 0
    TI__Guru**** 166176 points
    Chen,

    Regarding Q1, what is your resistance from the SRN pin to the battery pack? If there is a high resistance path (connector, cables, thin board trace) or the battery is inherently high impedance, then the battery taper time is longer because the voltage sensed at SRN VBATCELL + (RBATIMP + RPARISITIC)*ICHRG. Can you lower the cell voltage? What is the PRECHARGE/ITERM setting? If you lower the ITERM setting, the charger will charge more fully but it will take longer.

    Regarding Q2, setting the VBATREG higher with difficult VFB resistors in order to prolong CC fast charge and delay taper is the only option for making the charger with high RBATIMP and RPARISITIC charge faster. However, there is a risk that the charger will be overcharged. TI's BQ25890 family of 1S chargers has a feature called IR Compensation that raises the BATREG voltage to account for high resistance connection to the battery until the charger gets close to termination, in order to delay entry into taper. In theory, if the RBATIMP and RPARISITIC are known, you could use additional circuitry to implement this same feature.
  • 0 in reply to Jeff F
    TI__Guru**** 166176 points

    I mistyped above. With external FB resistors, you can connect the top FB resistor very close to battery connection. The charger uses that connection, not SRN, to determine point of regulation.

  • 0 in reply to Jeff F
    Prodigy 110 points
    Hi,

    big,thx
    So,conclusion is that external FB top resistors should be close to VBAT , and it could make charger more fully,
    my cell battery could stop 97% fully automatically, it is fine about the overcharged problem.
    And i could tune FB top resistors for Vfb?
    Truly,My layout placement for FB top resistors is behind BQ24610 , not near Vbat.
    I would try this point.
  • 0 in reply to Jeff F
    Prodigy 110 points

    Hi,

    I still can't charge more,

    i think the path is too long from SRN pin to VBAT and  from VBAT to Vfb,(The mechanical design cause this situation)

    so ,does there other way to cheat BQ24610 to let it charge more?

    I mean from BQ24610 to VBAT is really too long, i need to use connector and cable ,and other small board to connect both.

    and there is no work to tune FB resistor (that show STAT1,2 is high and high , and then no charge in progress)

  • 0 in reply to Joel Hernandez II
    Prodigy 110 points

    Hi,

    Yes,i have a battery fuel gauge with I2C detect in battery.

    The voltage is detected about 13.06V~13.07V when 92% full.

    So , i need to change the feedback resistor ,right?

    I mean let BQ24610 more closer to battery?

  • 0 in reply to Chen Yuan
    TI__Mastermind 25800 points
    Hey Chen,

    What is the battery regulation voltage you need, and what is the battery regulation voltage you are getting from your board?

    I have a feeling the feedback resistor tolerance is playing more of a role here than not. I would also confirm that battery are using is correct. How are you deciding 96-97% full? Are basing this solely on voltage? Or do you have a battery fuel gauge?


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    TI__Genius 10240 points
    Hi there,

    We haven’t heard back from you. We are assuming you were able to resolve your issue. If not, just post a reply below or create a new thread if the thread has locked due to time-out.