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Charging li-poly with solar panel using bq24210 with load connected

shahbaz sarik
Prodigy 200 points

Hi,

I am charging a 3.7v 510mAh li-poly battery with a 6v - 600mA solar panel. The load connected to the battery draws a maximum current of 200mA.

Is it fine to connect both the charger and load at the same time to the battery terminal?

How can I  make the system such that even if battery is charged but if solar panel is capable of driving the load then it will drive the load instead of the battery?

Thanks

Shahbaz

  • 0
    TI__Genius 13700 points

    Hello Shahbaz,

    Figure 2 on Pg 3 of the datasheet shows both the system/ load and the battery connected simultaneously to the BAT pin of the charger.

    The second question is answered by the charging diagram seen on Pg 10 of the datasheet. When the battery has reached a certain state of charge the system enters a state of constant voltage charging in which the battery current tapers off. This means that all of the additional power that is not being used to charge the battery will be sent to the load. In fact regardless of the batteries state of charge if the solar panel is producing more current than the battery will accept by charging the remaining current will go to the load and no power will be drawn from the battery.

    Let me know if you have any other questions or if anything was unclear.

    Ryan May

  • 0 in reply to Ryan May
    Prodigy 200 points

    Hi Ryan,

    Attached id the schematic of the circuit which I am using. Is this OK?

    I have not connected the battery yet, in absence of battery the CHG led glows till the input voltage (which is given through a supply) is above 3.6 volts but the PG led never glows ?

    Also the output voltage coming at VBAT was 4v but the battery will need 4.1 volt for charging, is there any issue?

    Thanks ,

    Shahbaz sarik

  • 0 in reply to shahbaz sarik
    Prodigy 200 points

    Also when I am connecting the led between VBAT ann PG it forces the led between VBAT and CHG to go low.

    If PG Led is not there then the CHG led glows for input > 3.6v.

    All these observation are done without any battery or load at VBAT.

    Can any one explain this behavior?

    Thanks and regards,

    Shahbaz sarik

     

  • 0 in reply to shahbaz sarik
    TI__Guru*** 146755 points

    Per the table on page 14, this appears to be correct operation because VTS = VTSB (therefore VTS>VLP(TS)) and BAT < BAT(SC).

  • 0 in reply to Jeff F
    Prodigy 200 points

    Hi Jeff F,

    Thanks for your reply!

    I am not able to understand why the on placing the led between VBAT and PG  forces the led between VBAT and CHG to go low?

    Is it safe to charge the battery with this circuit ?

    Thanks,

    Shahbaz sarik