Power modules
The modules assume that a 5V or 6V DC electrical power is available. 3 AA batteries, 4 recheargable AA or any USB power brick works in that setting.
The module color is blue for power modules.
Safety
All power modules should be protected against short circuits!
More choices
Lithium Polymer, Solar, wind, etc… There is a lot more options to store electrical power. Always make sure your power supply are fused.