Using back emf for charging window-blind controller battery
Theoretically that's impossible. When a coil rotates in a magnetic field a potential difference is generated across it. It may be a DC generator or a motor, that doesn't matter.
Consider a DC generator. If you rotate the shaft, a potential difference will be generated across it. As soon as you connect a load across it, current will start to flow through it. This current will oppose the reason of it's creation. i.e. it will try to slow down your shaft. Then you have to apply more mechanical power to the shaft to maintain your desired frequency.
In case of motor, you are supplying electrical energy and the shaft rotates utilizing it. A soon as the motor starts to rotate, the generator effect stars to appear. Because a coil is moving in a magnetic field. A voltage is gradually developed across the motor which is known as the back EMF. It opposes the applied EMF.
Let's assume that you have connected something across the generator created inside the motor(i.e. back EMF). As you are drawing current from the generator it's shaft will be slow. That's actually the shaft of motor which is getting slow. So if you want your motor to run at the previous speed , then you have to increase your input power. Otherwise the motor will run slower.
So,Connecting a battery across motor won't utilize the back EMF. It will increase the  line current.
You have given a link of regenerative braking. It's not simply like a battery connected across a motor. It uses the generator effect to slow down the wheel as soon a the motor is turned off.