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BQ24618: External Charging Circuit

user6310179
Prodigy 180 points
Part Number: BQ24618
Other Parts Discussed in Thread: BQ24610, BQ24600, BQ24610EVM

Hello TI, 

I am currently designing a battery management system. All parts are functional and it includes a 6 cell pack (4P-6S) (3500mAH cells) total voltage of 25.2 when fully charged. It has a MCU, coulomb counter, third chip that has 14 bit ADC, SOC LEDS, balancing circuit, and a bidirectional switch to turn off charge and discharge when needed. The current design does not have a charger built into the schematic/PCB. I am wondering two things:

2) Does TI foresee any problems if the bq24618/bq24600/bq24610 charging circuit is external to this? I am planning on building this charger separate and connecting it to the top cell and ground of the other BMS PCB. My other circuit can handle balancing the cells and cutting off charge during overvoltage situation. I am planning on using the max charger current of around 10A. 

3) With a charger voltage input max of 26V, can the BQ24618 charge a 25.2V battery? I saw somewhere in the datasheet that a higher voltage might be recommended. 

Thank you for your help. 

  • 0
    TI__Genius 10240 points

    Hi there,

    Thermal could be an issue for 10A charging. The PCB should have enough copper areas at different layers for power dissipation. The maximum 26V of the input voltage for the battery charger should also have tolerance. Because of the lower input voltage and the voltage drop on the charging path, the battery might not get fully charged. You might want to evaluate the performance for your application with BQ24610EVM first.    

    Best regards,

    Eric

  • 0
    Prodigy 180 points

    Hi Eric, 

    Thank you for the information. I was worried that it might not get fully charged since the datasheet said the input charger should have 2V more than the battery voltage. I would risk breaking the chip if I used a 28V charger? 

    Thank You,

    Brendan 

  • +1 in reply to user6310179
    TI__Mastermind 40375 points

    Hello Brendan,

    The recommended input range is up to 28 V, so this is the upper limit of what we would support.

    Thanks,

    Mike Emanuel

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