Part Number:BQ25570
I create a PCB with the attached schematic. I tried to follow the application in the datasheet. I added the lithium-ion battery protection circuit but this should not affect the charging of the battery. I am using a couple 3V solar cells from powerfilm solar (part number LL3-37) on the Vin-DC pin. I hve ground the EN pin on the PCB. There is no MCU control to this circuit. Finally, the Lithium battery is currently at 2.049V and I am attempting to charge it without a load on Vout.
I have tried both a single solar cell and 2 solar cells in parellel. The open circuit voltage is 3.0V. However, when I connect the solar cells to the BG25570 on the Vin-DC the in circuit voltage drops to 0.432V. .... not 80% of 3 V as the datasheet says it should.
When I add light to the solar cell the voltage on the battery is slowing increasing about 0.001mV every 15 seconds so it is doing something but it never gets up above 2.1V. Clearly the 3.7V lithium battery is not charging.
I am sure it has something to do with the configuration of the IC. The in circuit voltage on the Vin-DC does not increase when I use 2 cells or 1 cell. The voltage on the solar panels is always 0.4 something volts not 80% of the 3V open circuit voltage.
Any idea what I am missing. Attached is the schematic.
Thanks,
