Once the circuit is assembled and set up, the below shown design can be used for charging any spare Li-Ion Battery through the 5V Mobile Charger or USB port.
First connect the battery across the indicated points, and then plug in the USB connector with your Mobile Charger or computer’s USB socket. The green LED should instant become ON indicating the battery is being charged.
You can attach a voltmeter across the battery to monitor its charging, and check whether the circuit cuts off the supply correctly or not at the specified limit.