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BQ24650: Design Queries

ikon
Genius 5355 points
Part Number: BQ24650

Hi Support, queries below.

  1. If I connect the load (4x3W LED light) direct output from Battery (Lead Acid / LiFePO4) do I need to adding the protection circuitry? Limit the voltage draw ≥10V?
  2. The reference design setting is it suitable for both Lead Acid / LiFePO4 battery?
  3. For our design the load will not connect to VSYS, but is connect to VBAT is it ok?

Thanks.

  • 0
    TI__Genius 10240 points
    Hi Ikon,

    The battery pack protection is needed for safety and it is independent of the charger for safety.
    The BQ24650 has VFB pin to set the battery voltage, so it is suitable for LiFePO4 battery. The Lead acid charging profile is different and not recommended for Lead-acid battery
    It is ok to connect to the load to the battery. In this case, you don't need the D3, which to generate the power path function. The power path function is to allow the system powered up instantly from the adaptor under the condition that the battery is drained.
  • 0 in reply to ezhao
    Genius 5355 points

    Hi Eric,

    So the BQ24650 is just for charging the LiFePO4 battery, am I right? If I need to charge the Lead-acid battery mean need to use other type of charging IC right? Could you please recommend?

    BTW, for the 2 type 18V (AC/DC adaptor & Solar Panel) of input no issue?

    Need to add any over discharge voltage protection circuitry on the battery to the load?  

    Thanks.

  • 0 in reply to ikon
    TI__Mastermind 25800 points
    Hey ikon,

    The BQ24650 can be used for charging most Li-ion based chemistries; not just LiFePO4.

    As Eric mentioned, this charger's profile is not suited directly for Lead Acid batteries as it has no float charge capability. It only has a recharge threshold to re-initiate charge when the battery's voltage falls below a certain threshold. If you can accept this, then you may use this charger. This charger still has the characteristic CC/CV profile that Li-ion and Lead-Acid requires.

    As far as the inputs, there should be no issue as long as you program the MPPSET pin correctly around your solar panel's maximum power point correctly.

    In regards to over-discharge protection, I would highly recommend this. Deeply discharged Li-ion and Lead-Acid based chemistries can fail without recovery. Typically this protection is added to the battery side to create a "battery pack". This pack is what would typically be connected to all other system components including charger and load.


    Regards,
    Joel H