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battery charging

sagar wadi
Prodigy 20 points
Other Parts Discussed in Thread: BQ24020, BQ24210

I am using BQ24020DRCR IC for charging a 1800 mah battery with solar panel connected through USB.

i have set RSET=1000 Ohms.

when my battery is deeply discharged solar panel is unable to provide pre-charge current and charge the battery.  whereas AC  adapter is able  to provide pre-charge current. i want to know why solar panel IC Is not able to provide pre-charge current and is there any alternative IC that i can use to overcome this problem..

my solar panel produces 5v, 250mA current. in bright sunlight.

thanks in advance

regards

sagar

  • 0
    TI__Guru**** 165886 points

    The bq24020 was designed to be powered from a source with low output impedance like USB port or wall adapter.  A solar panel is a high impedance source and so can be collapsed if too much current is pulled from it.  That said, pre-charge current is very low and I would expect the solar panel to easily provide pre-charge current. 

    Regardless, I suggest you change to the bq24210.  It has a feature to pull the maximum power from the solar panel without collapsing it, which is helpful at high charge currents.

  • 0 in reply to Jeff F
    Prodigy 20 points

    thank you sir it was really a valuable information.

    i am also quite shocked as even though pre-charge current is very less solar panel is still not able to provide it.  however once i charge deeply depleted battery for less than a minute with ac adapter then solar panel is able to provide pre-charge current (interesting),  i wonder what special action ac adapter is doing in that one minute that helps solar panel to provide pre-charge current later.

    anyway bq24210 is a great IC but it has a single input pin,but i was looking for ic with two input pins so that solar panel can be always kept connected to circuit and i will be even able to charge with ac adapter whenever i like.

    any suggestion would be appreciated

    regards

    sagar