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Original question:

BQ34Z100-G1: Parallel Pack li+ with MPPT cahrger

BQ25896: 8P Li+ Battery Pack Charging and its Performance and problems with MPPT charger

Ayla Shiva
Intellectual 680 points
Part Number: BQ25896

I have built a 8P Li+ 18650 Battery pack and charging it through a MPPT Bq2589x Charger IC, the Issue I have found is the battery pack is not delivering any Voltage below ~3.5V, I suspect any Balacning to be done for the batteries, But its parallel charging, Is that balancing still needed.

P.S: The batteries are of Same chemistry from SAMSUNG, Type:ICR and it had been charge for full, Before when it is used with the MPPT charger.

  • 0
    TI__Mastermind 27740 points

    Hi Ayla Shiva, 

    A battery pack with 1S8P cells should auto balance. No additional balancing is necessary. 

    Ayla Shiva said:
    the Issue I have found is the battery pack is not delivering any Voltage below ~3.5V

    Can you please elaborate on the issue you are seeing. Is the battery not discharging below 3.5V? Or is the battery not charging as expected when Vbat below 3.5V? 

    Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Intellectual 680 points

    Hi Garret,

    Using a Boost DC-DC at the O/P of Bq25896 to feed to our system. But when the battery Voltage is equal to/ drops below 3.5V, its unable to deliver the required voltage to system. The Charging is Fine, thought the battery pack voltage falls below/at 3.5V it 's able to charge again.

    Thanks

    Shiva.

  • 0 in reply to Ayla Shiva
    TI__Mastermind 27740 points

    Hi Shiva, 

    Ayla Shiva said:
    its unable to deliver the required voltage to system

    What is the minimum voltage required at Sys pin (i.e. input to boost DC-DC) for your system to function?

    When you say the battery is unable to deliver the required voltage to system do you observe 0V at Sys pin or 3.5V? If you are observing the current battery voltage (~3.5V) at Sys when no adapter is present the charger IC is operating as expected. 

    Regards,

    Garrett