Integrated helmet systems provide convenient and modular use of electronic devices with a protective helmet. In addition to ease of use, weight savings and space savings also may be realized in certain embodiments. A flexible printed circuit board is used as a power bus to deliver electrical power from a battery pack to various electronic devices. Examples of devices used with protective helmets include: night vision goggles; helmet-mounted display units; ear phones; communication headsets; camera systems; biometric sensors; microprocessors; identify friend or foe devices (IFFs); and GPS devices.