I was thinking about this the other night myself. I was thinking about mounting it in the rear of the body armor with a small laptop with good power connected to a USB HUB. Then anything you mount in the helmet itself (I was thinking of the lighting, small 2-inch monitor connected to a rear cameramounted in the back of the helmet, fans, etc) could be powered with USB. One cable to the helmet with the HUB mounted on the inside rear of side of the helmet. Then only one cable would be needed to connect the hemet to the laptop. With the minimal power draw the laptop could last several hours. Possible a netbook, becuase they are small and not
equipped with moving parts (DVD ROM).
As for the the electrical shoc potential, if your power draw is minimal and you use the proper sized wiring for the power draw you should have adequate insulation and low-heat build-up. If you go the USB route then the porblem is moot, provided your connections are insulated. Air flow may be an issue.
With your concept Iticha, I am not sure on the size on the AI chip, but what about incorporating the batteries into the design. Like a 4 AAA battery pack that you put your rechargable batteries into then insert the chip into the helmet and activate the accesories. When the chip is removed then the system is unenergized.