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BQ24650: Charging issue

Cherry Zhou
Mastermind 22235 points
Part Number: BQ24650

Hi team,

Here's an issue from the customer may need your help:

Charge 12V lithium battery with gauge and 18V/55W solar panel at power input.

In wet weather, the charging light dose not come on (nor does the full-charge light come on), indicating no charging. A multimeter is used to test the lithium battery voltage at 10.8 V and the solar panel output voltage at 20 V. The MPPT (1.2 V) set point voltage is 17.8 V.

Reseat the power input connector once and find the charge LED lit. At this point, the solar panel output voltage is 17.9V

The customer would like to know why does the charging light not light up when the solar panel output voltage is 20 V at the beginning, and it does come on after reseating (powering on)?

Thanks.

Best Regards,

Cherry

  • 0
    TI__Mastermind 40375 points

    Hi Cherry,

    We will get back to you after the Thanksgiving Holiday. 

    Regards,

    Mike Emanuel

  • +1 in reply to Michael Emanuel35
    TI__Mastermind 40375 points

    Hi Cherry,

    If you are in wet conditions, it is likely you are getting low solar output because the cells are not irradiated. As such the charger may not be able to draw enough current. In your case it looks like the solar panel may be open-circuited to its OCV 20 V voltage.

    When you reseat the connector, the irradiance may have changed allowing more current to be pulled from the solar panel.

    It is likely in some situations you cannot provide enough power, and the charging current drops as shown in Sections 8.3.2.

    How does the part perform in sunny conditions?

    Regards,

    Mike Emanuel