When my previous 12" Retina Mac went in for Mac warranty service they discovered the battery was badly swollen which required the replacement of the entire unit. I just updated the OS of replacement unit yesterday to Catalina 10.15 principally because of the new battery health feature, which might have prevented the battery issue on the old one. IMAGINE MY SURPRISE when I discovered that the new battery health feature was not on my new OS. I called Applecare, who checked and discovered that the feature is only installed on recent MacBook Pros and MacBook Airs (models from the last year or two), not any of the Retina Macbooks. Since the Retina Macbooks are the ones that may turn out to need it as much as if not more than the others (no internal fan on those units means more likely overheating) it seems like someone is asleep at Mac HQ. Hope the wake-up feature in the operating system works for the engineers as well.?