How large is the battery charge current?

A project log for Solar harvesting into Li-ion battery

This is a 0.8x0.6 inch board with AEM10941 solar harvesting IC charging a Lithium Ion battery

Jasper SikkenJasper Sikken 09/21/2018 at 14:450 Comments

I have measured AEMLION battery charge current using three different solar panels in indoor light (500 lux), outdoors in the shadow, and in full sun (~500W/m^2). 

Solar panelindoor 500 luxoutdoor shadowoutdoor full sun 500W/m^2
1V/100mA 30x25mm50uA700uA5mA
2V/100mA 79x28mm100uA1.8mA10mA
4V/100mA 70x70mm280uA4.8mA20mA

Indoors (~500 lux) and with the smallest solar cell the battery is charged at 50uA for 10 hours. Then the application must have an average current of (50uA*10hrs/24hrs) 20uA or less. That's enough for a simple Bluetooth Low Energy beacon or a very simple LoRa application. If that is not enough you need to select a larger solar panel. 

Outdoors in shadow current is 10-20 times larger. And in sun 100 times larger. 

As you can see the AEM10941 can charge a battery from indoor light but indoor light is really only suitable for very low power applications.