Will Wi-Fi drain my battery faster?
Data Connection Optimizer is designed to have negligible impact on battery life when compared to an equivalent device that has Wi-Fi enabled. If you notice a change, it may be because your data consumption is increasing and/or because the screen is enabled more often. Wi-Fi can be easier on the battery than 4G/3G. Your phone needs a lot of battery power to maintain connection with the cell towers, and even more to transmit data to and from them. Wi-Fi radios use much less power because of their design, their close proximity to the hotspot, and they do not have to keep searching for a better access point.