vampire load
n.— «In the lingo of energy experts, devices that draw power even when turned off or idling are called “vampire loads,” because they suck energy constantly. There are also “wall warts,” devices like cellphones, digital music players and personal digital assistants that require a small charger or adapter; many of those adapters deliver only half of the power they draw in, with the rest wasted. » —“Is the TV Off? No, It’s Really on Standby, Using Current” by Sewell Chan New York Times Aug. 7, 2006. (source: Double-Tongued Dictionary)