It may be related to mobile network. I have suffered a lot about 3 months after buying the phone. For the last two month the problem is gone. Before i used a subscription from a network provider(teletalk) in my country, which is reputed bad for poorly optimizes network. The day i switched to new network provider which has a moderate reputation(Grameenphone) in my country my battery drain problem is gone. On the older network i used to get 3-5 hr of SOT on a 10-13hr usage and idle battery drain was 3% per hr. Now I'm getting 5-7hr SOT on a 16-22hr usage with no power saving whd+ regulation. For me the culprit was bad network and the phone was fine. Try switching network provider (if possible). And see if ur device is faulty or its just badly optimised network?
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