Hi. I just got this battery installed from a tech shop in my city: NewerTech NuPower 78 Watt-Hour Battery for MacBook Pro 15" Unibody Mid-2009 & Mid-2010., with a new 256MB SSD hard drive. I am concerned that the battery isn't living up to its "potential" as I am only getting maybe 4-1/2 hours out of it from a full charge when it is unplugged. I ran a time test the other day that resulted in the following: Beginning at 100%, at 4:43 p.m, I unplugged it to run on battery alone (this is with an upgrade to OS High Sierra). At 6:55 p.m. the battery was at 58%. At 8:41 p.m. the battery was at 27% At that point, I connected the charger. Knowing nothing about this particular battery, or any battery for that matter, is this a normal amount of discharge for a third party battery running in an older machine? Should I return my unit and ask for a new battery, as I am still under warranty. Thanks.