Researchers at the University of Michigan are working on a power management system that could significantly cut the energy that most smartphones waste while in sleep mode. The Energy-Minimizing Idle Listening (E-MiLi) system works by reducing the battery drain by changing the way the devices “sleep.” E-MiLi works by reducing the clock speed of a phone’s WiFi card to as little as 1/16 of its normal speed – a kind of “subconscious mode.” The reduction in frequency reduces the load on the phone’s battery, though the phone can still receive data. When it needs to function, it turns the WiFi frequency back up and receives the data at normal speed. At the moment, E-MiLi is at the proof-of-concept stage. Doctoral student Xinyu Zhang and computer science and engineering Professor Kang Shin have shown that their system works in a range of different smartphones – according to their figures they were able to see a 44 percent improvement in battery life in 92 percent of the mobile devices they tested using regular wireless networks. The best results saw battery life boosted by 54 percent. If E-MiLi makes its way into production, forgetting to plug your phone in before bed may become a little less of a big deal. Before that can happen though, WiFi chipset manufacturers will have to start producing E-MiLi-capable chipsets, so Zhang and Shin will have to get smartphone manufacturers to get on board. The problem with their system is that in order to receive calls, the caller -- not just the E-MiLi receiver -- needs to have firmware installed. Otherise, the call won't go through, a pretty big downside. Still, with battery life in many smartphones dismal at best, manufacturers may be prepared to consider such a move.