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BQ24650EVM-639: BQ24650EVM-639

akanksha upadhyay
Prodigy 40 points
Part Number: BQ24650EVM-639
Other Parts Discussed in Thread: BQ24650

The default current setting of BQ24650  Development board was 2A i tried to increase it to 8A by changing the following.

1. Inductor of 3.3uH

2 . Output capacitor(C2,C1,C7) , 10V,10uF ,  4 connected in parallel  value comes to about 36 uF.

3. R6 resisitor R005, 0.005 ohm. 

Still it is  able to handle 4A max. How to increase ?

Thanks and Regards

Akanksha

  • 0
    TI__Mastermind 40845 points

    Hi Akanksha,

    What is the voltage on the MPPSET pin? Is your input capable of providing that power without triggering the MPPT?

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 40 points

    It's 1.2V , and as it is cloudy here so i am using dc power supply  instead of Solar panel. Voltage set between 16.0 to 16.3V. Battery i am using is LIFEPO4 and its maximun voltage is 14.4V and nominal voltage is 12.8  but i have not changed the default  feedback voltage setting from 12.6V .Will changing it to 14V help in increasing the charge current?

  • 0 in reply to akanksha upadhyay
    TI__Mastermind 40845 points

    Hello Akanksha,

    The default MPPT voltage on the board is 17.8 V. You need to present a voltage higher than that so that the MPPSET pin is above 1.2 V. Please try a higher rated input voltage (and make sure it can support the required current without dropping MPPSET below 1.2 V). If your power supply cannot support the 8A charge current without drooping you will need a higher rated input power supply.

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 40 points

    Sir as  i said my Vmmpt voltage setting was greater than  input voltage. At that duration my MPPT voltage set  by me was 15.83 and input voltage was 16.2 . what my problem is that inspite of changing all the specified components in order to increase the current(FOR 8A) ,it's going only to 4 A .Please answer it ASAP.

  • 0 in reply to akanksha upadhyay
    TI__Mastermind 40845 points

    Hello Akanksha,

    I am having trouble understanding your setup. In the first post you said you only changed three things: Inductor, Output Capacitor, and Sense Resistor. I have several comments.

    First, the total output capacitance recommendation refers to the capacitance on VOUT, specifically where C7 and C8 are. C1 is the capacitor for the SYS rail and C2 is the capacitor for the input of the converter. You need the recommendation where C7 and C8 are.

    Second, no mention was made of changing the MPPSET divider, or R17 and R19. This means the default MPPT setting for this board is 17.8 V for the board. If the divided VIN leads to MPPSET being 1.2 V or less in operation, the charge current will be reduced or stop altogether. You need an input voltage that will keep the MPPSET pin above the required threshold.

    Third, if you are in CV mode your current will be reduced until termination. It is possible you need to adjust your voltage divider for the charge voltage (R13 and R15) to make sure you are not in CV earlier than expected. What is the FB voltage and SRN voltage when this is happening?

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 40 points

    Hello Mike 

    I just changed the C7 and C8 capacitor with 36uF/10V and i don't know how my battery BMS got damaged .Why?

  • 0 in reply to akanksha upadhyay
    TI__Mastermind 40845 points

    Hello Akanksha,

    Unfortunately I cannot debug the charger with the information provided. Can you please provide more information? Have you tried charging another battery? Have you tried using another EVM? Can your provide waveforms of the input voltage, output voltage, charge current, and PH node?

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 40 points

    Hii Mike ,

    I have tried it on another battery and on that also board is not drawing any current . I think it has got damaged and no i have not tried it on another EVM .I will  be sending you waveforms ASAP.