I have a simple project I need help with. It's a dual 10 LED light which hangs from my glasses to light the area I'm working on. It's nothing major but, I'm good at 3d printing but know very little in electronics. They are 3 mm LED's 3.2 volts 20 ma. Can someone help me with wiring this to an easy battery pack that I can attached to my belt etc. It needs to power 20 of them and last for 2-4 hours maybe. thx!