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Original question:

BQ24650EVM-639: Charging LiPo Batteries

BQ24650EVM-639: BQ24650EVM-639

Priya G
Prodigy 30 points
Part Number: BQ24650EVM-639
Other Parts Discussed in Thread: BQ24650

Hello,

I'm trying to charge a 12volts rechargeable  lead acid battery using BQ24650EVM-639.can I do so or is there any specification for the batter to be used.

lastly, what is the input voltage that is required from the solar panel which is connected to charge the battery? 

  • 0
    TI__Mastermind 24075 points
    Hi Priya,
    Yes, you can use BQ24650 to charge lead acid. Here is an app note that discusses this application: www.ti.com/.../slva437a.pdf
    For BQ24650, as it is a buck charger topology, you will need VIN higher than battery voltage. This part has a sleep mode where it suspends charge if VCC~<SRN+500mV. It is recommended to have an input voltage of at least 1.5 V to 2 V higher than the battery voltage, taking into consideration the DC losses in the high-side FET (Rdson), inductor (DCR), and input sense resistor (between ACP and ACN), the body diode drop of RBFET between VCC and input power supply, and battery sense resistor (between SRP and SRN).
  • 0 in reply to Kedar Manishankar
    Prodigy 30 points
    Thank you sir,
    I tried giving a 9 volts input to the BQ24650 but the output was more attenuated and it was just around 3 volts.How can I solve this since the output obtained is very low?
  • 0 in reply to Priya G
    TI__Mastermind 24075 points
    Hi Priya,
    Are you using a 12V lead acid battery in the test performed above? What is connected at the output? Keep in mind, that your input voltage must be higher than measured battery voltage by atleast 500mV, measured close to IC, to avoid going in to sleep mode.