This tutorial will show you a nifty way to make a variable power supply using neodymium magnets, coin cell batteries and two alligator clips. You can also use this as a standard battery holder by using only one coin cell battery.
Notice how your LEDs get dimmer when you have many of them? Having multiple batteries in series makes a stronger power supply that will help your LEDs shine brighter. To learn more about series circuits, visit this tutorial on series versus parallel circuits.
1. Put one magnet on the positive side, one on the negative of your battery.
2. Add the other battery. The positive side of this battery should be facing the negative side of the other.
3. Now put the last magnet on the negative side of this battery.
4. Put the alligator clips on the top and the bottom of your battery-magnet sandwich. All of these pieces should snap together.
5. Stack as many batteries as you like using this method! Be careful, as you add more batteries, the current going through every LED increases and this might cause them to burn out.
Here is an LED connected to two stacked batteries in series (above) versus one battery (below). Note how the LED powered by two batteries is brighter!