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BQ25505: Charge supercapacitor through BQ25505

Part Number: BQ25505
Other Parts Discussed in Thread: BQ25570

Hi, support team

My customer has the questions as follow:

I use 3 solar panels with open circuit voltage of 2V and short circuit current of 69μA in parallel to charge 0.1F 5.5V supercapacitor through BQ25505.
I charge at 400lux for 1 hour and the supercap voltage is only 322mV.
My input voltage is always around 340mV. Is it normal to charge like this?

Thanks so much.

Best regards,

  • HI Yuki,

    Your solar panels are not providing enough power to get the charger out of cold start, possibly due to the supercap's high leakage current.  With your panels, I recommend changing to BQ25570 and charging the supercap from the buck converter (VOUT).