The present invention provides for devices and methods for making and using an integrated rechargeable power supply and power management system for providing power to weapon mounted electronic devices. The inventive apparatus provides for a common power source for weapon attachments, that can be integrated into a weapon. These devices and methods provide for an easy swap of the power source in an active environment, and further includes power management and safety functions. The inventive devices and methods further provide for better ergonomics and improved weight/balance to enhance shooting skills, less physically taxing heft, and potentially save lives. Finally, the present invention is backwards compatible with present weapons.