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BQ25895: Suitability for 12V to 3.7V Li-ion, 21000mAhr battery pack charging in Automotive environment.

Mansoor Sohani
Prodigy 20 points
Part Number: BQ25895
Other Parts Discussed in Thread: BQ24105-Q1

Can this device be used for charging Li-ion 1S-7P, 21000mAhr pack from a 12V automotive supply? Fast charge is not a requirement.

  • 0
    TI__Guru**** 166626 points

    Hi Mansoor,

    The BQ25895 is not auto qualified but can charge your 21AHr battery from 12V input.  At 12V input, the charger is least efficient and will therefore I recommend good heat sinking through the charger's power pad to dissipate heat loss, especially at higher currents.  This will prevent the charger from going into TREG, reducing charge current in order to protect itself. Slow charge is okay but you will need to size the charge current based on the safety timer.  For example, with default safety timer = 12 hours, you will need to charge at greater than ICHRG = 21A/hr / 12hr =1.75A or increase the safety timer.

    If you need an auto qualified charger, I recommend BQ24105-Q1.

    Regards,

    Jeff 

  • 0 in reply to Jeff F
    Prodigy 20 points

    Hello Jeff,

    Thanks for the response. I looked into BQ24105-Q1. The only downside I can see is that while charging 21AHr pack, it will not be able to provide the 0.1C.

    That said, there may be a possibility to add an external switching element to provide over 2.1AHr to kick start the charging. I am going to explore that. If you know a sample design with such an arrangement, please point me to it.

    Thanks

    Mansoor