Ever since I got mine, I've never put it to sleep, or even turned it off for that matter. I just put it down when I sleep, and when I pick it up to vape in the morning, the battery is exactly the same, no matter which battery I've put in it. Have you been charging the battery through the USB? I never do that, I always use a dedicated external charger. If you have, maybe the overcharge protection circuit failed and now your battery just won't be able top hold a charge for very long anymore. So try a different battery first ( hopefully charged through a proper external charger), and see if it drains. If it does, it's the mod, and needs to be exchanged. If it doesn't, It's the battery, and it needs to be tossed. As a general rule of thumb, all batteries should be charged through a dedicated charger where applicable.