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BQ24075: how to extend the life of li-ion batteries that are only used as emergency backup

Zhiyong Li (FT)
Expert 2610 points
Part Number: BQ24075
Other Parts Discussed in Thread: BQ25606, BQ24079

Hi,

We have been using BQ24075/BQ25606 to charge the li-ion batteries. Because our system is mainly powered by mains, and li-ion is only used as backup when mains is off, so most of time li-ion batteries is idling at full charge. Over years, the battery will slowly and gradually degrade, eventually to the point that they can no longer provide any meaningful duration of back up. 

I have learned that if we don't let li-ion batteries idle at full charge, but instead at 70 ~ 80%, their life will be greatly extended. BQ24075/BQ25606 etc. all come with a charge enable pin. So in theory, we can use external signals, such as GPIO pins from MCU to stop charging before battery reaches full charge.

Does TI have an application guild on how to go about this?

Update: after going through similar posts, I realized some charging IC terminates charging at 4.1V, such as BQ24079. I assume terminating at 4.1V will solve the problem.

So a related question is: is there any charging management IC that terminates at 4.1V? Particularly those with boost capabilities such as BQ25606?

Thanks in advance,

ZL

  • +1
    TI__Mastermind 23170 points

    Hi ZL,

    Looking through the charge selection and filtering out for chargers with a standalone control topology and sorting by charge current, you might take a look at the BQ2530X family. I've provided the device comparison table for your reference. 

    You can look at their respective datasheet for configuration.

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Expert 2610 points

    Hi Mr. Pham,

    Thanks for your reply. Later I found out that BQ2616 can be configured into terminating at 4.1V with an external pull down resistor. That seems requires the least modification to existing design, so we will go with that IC. But still, thanks for pointing to BQ2530x.

    Best,

    ZL