What electric setup do I need to get electricity from a BLDC motor?
Yes, what you need is a 3 phase rectifier. If you have access to an oscilloscope, you should use that to measure the output voltage (and ripple). Storing the energy converted by your BLDC motor in a battery is more complicated than rectifying the output, but it may not be necessary. You can use a resistor as a dummy load to simulate charging a battery if that is out of scope.