I have a 2W solar panel with an open-circuit voltage of ~6V, when I connect it to VIN of the BQ24075, it drops to about 4.5V and the CHG LED indicates it is charging. However, there is no change in mA,mV,mW of the charge circuit (BQ27441). After about 30 minutes of charging (no load), there is no change in the State of Charge (soc %). I am using a 3.7V 2Ah LiPo battery. Is my battery charging?

I have tried all three modes on EN1, EN2… the full 1.5A does not seem to work as it loads the solar cell below the VDDO threshold of 4.35, but both 500mA and 100mA hold a steady voltage at the solar panel. The datasheet of the 24075 indicates it likes to regulate the voltage at VOUT at 5.5V, whereas the 24072 tracks VBAT + 225mV. I had assumed this chip would still be able to charge the battery as long as the VIN was above VDDO (4.35). Can anyone help me understand what is going on?

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    \$\begingroup\$ Could you post a block diagram and a link to a datasheet of all the devices your using? \$\endgroup\$ – Voltage Spike Sep 14 '16 at 16:01
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    \$\begingroup\$ Also measure the actual current from the solar cell. \$\endgroup\$ – user_1818839 Sep 14 '16 at 16:02

FYI, I found the problem... when placed in more direct sunlight, the panel supplies more current, which the BQ24075 seems to manage between the battery and load very nicely.

Thanks for your support!


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