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BQ25820: MPPT solar charger IC for 40+A (LifePo4 pack)

Matija Gluhak
Prodigy 30 points
Part Number: BQ25820
Other Parts Discussed in Thread: BQ25756, BQ25750, TIDA-010042, BQ25756E

Tool/software:

HI, i am trying to design MPPT charger that will be able to charge 12V or 24V LifePo4 battery packs (usually 300Ah or more).
Solar panels are from 12-50V range and input current in some cases above 40A. Batteries can be charged with 150A in CC mode so i would like to use maximum power from panels.

For now, my research on this forum was about BQ25756, BQ25820, BQ25750. Now all of them have a current limit for 20A, since i don't need reverse mode BQ25820 was the best option I found, but the problem is that in the datasheet BQ25820 and BQ25750 only do panel sweep option for MPPT tracking while BQ25756 after panel sweep is doing pertrud and observe and only has P_AND_O_TMR register.

Now my questions are

1. Am i on the right track for valid MPPT IC for my case (input: 12-50V, 40+A output:12-29V 40+A)
2. IF BQ257xx series are the way to go, am i locked to 20A current or that can be higher (putting 2 BQ chips on the board won't work since they are using the same IC2 addresses and won't work on the same solar input)
3. What about TIDA-010042 is that something i should be focusing on, but that will require MCU to calculate PWM for MPPT and it is limited to 16A but i think that can be set higher up to 35A since the driver can handle that or what should be my options. (can uC be ESP32 ?)

Chargers will be installed on the boat where solar panels are moving a lot so MPPT tracking is very important (panel sweep timer is I think 3 minutes minimum or forced and I am not sure how long it takes to scan, on some of your videos i have seen around 3-6 sec for full range).

Thank you for any advice!

Kind regards,

  • 0
    TI__Mastermind 32346 points

    Hello Matija,

    Matija Gluhak said:
    1. Am i on the right track for valid MPPT IC for my case (input: 12-50V, 40+A output:12-29V 40+A)

    I would recommend BQ25756 or BQ25750. BQ25820 is a buck only charger, so the input voltage will always need to be higher than the battery voltage in order to operate correctly.

    Matija Gluhak said:
    2. IF BQ257xx series are the way to go, am i locked to 20A current or that can be higher (putting 2 BQ chips on the board won't work since they are using the same IC2 addresses and won't work on the same solar input)

    The maximum charge current is 20A, it might be possible to use BQ25756E and BQ25756, these two device have different I2C addresses.

    Matija Gluhak said:
    3. What about TIDA-010042 is that something i should be focusing on, but that will require MCU to calculate PWM for MPPT and it is limited to 16A but i think that can be set higher up to 35A since the driver can handle that or what should be my options. (can uC be ESP32 ?)

    I'm not familar with this reference design, so I cannot comment on the capability of that device.

    Matija Gluhak said:
    I found, but the problem is that in the datasheet BQ25820 and BQ25750 only do panel sweep option for MPPT tracking while BQ25756 after panel sweep is doing pertrud and observe and only has P_AND_O_TMR register.

    Unfortunately, the BQ25756 does not support P&O, This is a typo in the datasheet. We currently do not have a charger that supports this feature, however my team is working on an appnote on how to implement this feature externally.

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    Prodigy 30 points

    Hi Christian and thank you for replay.

    I am not able to use BQ25756E in combination with BQ25756 since the max voltage is 36V on the "E" version. 

    My main question was to pick the right IC chip for my needs with a higher current.

    TIDA-010042 (https://www.ti.com/tool/TIDA-010042) uses P&O but I am not sure that it manages the LifePo4 batteries cycle can you check that for me, please?

    Do you have any information about the upcoming app note? Will it be software-IC controlled, and when will it be available?

    Kind regards.

  • 0 in reply to Matija Gluhak
    TI__Mastermind 32346 points

    Hello Matija,

    Matija Gluhak said:
    TIDA-010042 (https://www.ti.com/tool/TIDA-010042) uses P&O but I am not sure that it manages the LifePo4 batteries cycle can you check that for me, please?

    You will need to post a new question related to this referenced design, I do not support this product, so I can not provide any information.

    Matija Gluhak said:
    Do you have any information about the upcoming app note? Will it be software-IC controlled, and when will it be available?

    It will be softwared controlled, I'm still working on the code for the appnote. It's expected to be released by the middle of march.

    Best Regards,

    Christian.