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BQ24650: Charging with solar panel not working

Tobias Franz
Prodigy 40 points
Part Number: BQ24650

Tool/software:

Setup:

60W Charger with 5A maximum current and Lead-Acid battery.

Performed tests:

Power supply with 21V input and electronic load at battery port as output in CV mode - Test i.O. 60W/5A available

Power supply with 18V input and battery connected - Test i.O. charging possible

Solar panels as input and battery connected - Test not okay. Panel voltage drops for short spikes to 12V then charging restarts. Audible clicking noises from the inductor.

I am currently facing the issue that my designs works well with a power supply. When I connect a 30W solar panel the charging led lights up but there is no current flow.

The inductor makes audible clicking noises and indicates that the charging does not work properly (see picture below).

Pulling MPPSET to gnd restarts the charger but it always enters the same state.

What could cause this behaviour? It seems to me that the controller wants to draw more power from the panel than possible.

Green=Uin Solar Panel

Yellow =HIDRV

Thank you for your help and best regards

Tobias

  • 0
    TI__Mastermind 32236 points

    Hello Tobias,

    Have you tried testing with different solar panel?

    Is MPPSET being pulled below 75mV?

    The issue is most likly the solarpanel is not able to provide the required power, and the charger is repeatably crashing because of this.

    Best Regards,

    Christian

  • 0 in reply to Christian Moyer
    Prodigy 40 points

    Hello Christian,

    thank you for your reply.

    MPPSET is dropping but not under 650mV.

    The test was performed with two different solar panels (same type) with low light.

    In my opinion the light should have been enough to start charging. Isn´t the purpose of the MPPT-regulation to charge even under suboptimal light conditions?

    I will continue testing in January.

    Thanks again and best regards

    Tobias

  • 0 in reply to Tobias Franz
    TI__Mastermind 32236 points

    Hello Tobias,

    I'm looking into this issue, I will provide feedback after I gather more information.

    Best Regards,

    Christian.