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Overcharge protector for LiFePO4

Danilo A.
Mastermind 28720 points
Other Parts Discussed in Thread: BQ77216, BQ2970, BQ77915, BQ7716, BQ77905

Hi Team,

I have searched our list of battery protectors and it seems we only have solutions for lithium-ion and lithium polymer. In the customer's application, he will charge the battery from a solar cell with MPPT charger and would like to add a battery protector for LiFePo4 so an additional battery charger would degrade the efficiency. Is it possible to configure our battery chargers as battery protector for LiFePo4. Can you suggest any device for this application?

Regards,

Danilo 

  • 0
    TI__Expert 7465 points

    Hi Danilo,

    We have quite a few options for battery protectors, so it is important to look at a few key points in order to determine which will be the best solution for you.

    The most important factor is the number of cells in series. We have 4 different devices with configurations for LiFePo4, which means they have an OV threshold of around 3.8V. The first is the BQ2970 for single cell battery packs. The BQ2970 has over voltage, under voltage, and current protections. The second is the BQ77216 for 2-4S packs. The BQ7716 only has over voltage protection. The BQ77905 can be used for 3-5S battery packs that require over voltage, under voltage, current, and temperature protections. And lastly, the BQ77915 can be used in 3-5S battery packs that need over voltage, under voltage, current, and temperature protections as well as cell balancing. 

    Our battery protectors cannot act as battery chargers.

  • 0 in reply to Shawn Hinkle
    Prodigy 40 points

    Hi Shawn,

    In my design I will use only one cell, so 3.2 V. It is ideal because it will be charged up to 3.5 V so I do not need any dc-dc converter to power up my uC.
    I have looked at BQ2970 but it has too high over voltage protection. My battery supplier specified it's cells at 3.65 V max for charging. So I'm affraid 3.8 V is a bit too much, as I do not want to degerade the cells or risk a fire hazzard in case batteryes get overcharged. 
    Another thing is that they will be charged with low current of about 100 mA - 300 mA for 10 Ah battery pack. So in the case my solar charger starts overcharging the batteryes, it would take a lot of time before battery voltage rise up to 3.8 V for BQ2970 to detect it.
    Is there any way to manually set OV protection for a single cell sistem?

    With regards,

    Martin

  • 0 in reply to Martin Palenkic1
    TI__Expert 7465 points

    Hi Martin,

    Could you start a new thread with this request?