mid 2015 macbook pro DG. I replaced the OEM battery with a ZYTH battery. After 15 charge cycles I experienced this problem where on wake-up it showed a depleated battery icon on the screen and required power supply connect to wake. I reset the SMC and now it works. Short (minutes), medium (few houes) and long (many hours) sleep not on power and it will wake fine. So sometimes its not a chronic problem. But... maybe it will return. For now, that was my solution. FYI I get 3-7h on the battery - impressive!