• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 63 subscribers
  • Views 124 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24650: 30 Minute Precharge Timer

Santiago Vazquez
Prodigy 10 points
Part Number: BQ24650

Tool/software:

I am using the BQ to recharge a 30Ah lithium battery. I can't charge at more than 3A, so in the pre-charge phase, starting from a very discharged battery state, in 30 minutes I don't exceed the Vlowv threshold for it to enter the fast charge mode. Is there any way to increase this time? Is there a solution that does not involve increasing the charging current?

Thanks, Santi

  • +1
    TI__Mastermind 32236 points

    Hello Santi,

    Santiago Vazquez said:
    Is there any way to increase this time?

    Unfortunately we do not have a way to increase this time. Once the 30 minutes expires, it enters the fault condition, as seen in Figure 14 of the datasheet, if the battery does not exceed the Vlowv it will enter an infinite loop

    To get out of this conditiont, a new charge cycle needs to be toggled. To toggle a new charge cycle, either a power-on-reset (POR) event needs to occur, or MPPSET falls below 75 mV to reset charge enable.

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    Prodigy 10 points

    Thanks for the reply Christian.

    Searching in the forums about the same problem brings up an application note in which suggests through a resistive divider on the vref pin and a diode to falsify the measurement on the FB pin so that the BQ thinks it is always in fastcharge mode (or at least that's what I understood, please correct me if it is not true). I am aware that it is not recommended for the battery life but I would like to know if it could be another possible solution.

    Thanks, 

    Santi

  • 0 in reply to Christian Moyer
    Prodigy 10 points

    Hello again Chritian,

    In reference to doing a power-on-reset (POR), do you have an application note for this?

    Regards, Santi

  • 0 in reply to Santiago Vazquez
    TI__Mastermind 32236 points

    Hello Santiago,

    Santiago Vazquez said:
    Searching in the forums about the same problem brings up an application note in which suggests through a resistive divider on the vref pin and a diode to falsify the measurement on the FB pin so that the BQ thinks it is always in fastcharge mode (or at least that's what I understood, please correct me if it is not true). I am aware that it is not recommended for the battery life but I would like to know if it could be another possible solution.

    Typically is not reccomend to force device into fast charge mode, unless your fastcharge current is realtivtly low, for example 100mA.

    Santiago Vazquez said:
    In reference to doing a power-on-reset (POR), do you have an application note for this?

    We do not have an appnote. You will need an external host to either disconnect the adapter or pull MPPT below 75mV.

    Best Regards,

    Christian.