So a couple of days ago I bought a barely used/like new Macbook Pro Retina 15" (mid 2015) for 1000€, a bargain. Once I checked the coverage it still had on the Apple website I found I still had the Apple 1 year warranty until 17/02/2017 which means this computer isn't even 1 month old. Well, that also explains the 11 cycle count on the battery. Thing is, the battery seems to be a bit weird. First of all I notice I'm having lower battery life than I expected (Apple says it's up to 9h) and I'm getting 6 hours tops with screen brightness under 50%, surfing on Safari with no other apps open. I've checked the Activity Monitor multiple times, I stopped using Chrome, I think I'm kinda obsessed with this to be honest. I did a reset on the SMC, I've been "exercising" the battery, today I even dropped it low to 1% after charging to 100% and then I charged it back to full. Still the same performance. Also, the estimated time is always jumping up and down, even if I'm doing the same task with the same apps open. It can start high as 15 hours after I remove the charger and I'm not doing anything special, then it drops to 14, then to 12, then to 8, 7 to finally 6 where it kinda stabilises. Then it goes down to 5, then up to 5:30, then to 4:30, then to 5 again. It's incredibly annoying. And as I said above, it's not like I'm changing my activity, I'm actually trying keep always the same apps open just to test this as I'm typing. Another thing I noticed.. I downloaded coconutBattery to check the battery. The first time I used it, the day I bought the mac, it said the battery's health was at 96% which is low for a 11 cycle battery on a less than 1 month old mac. Today after I did the "calibration" thing I checked and it's up to 98,5% which I hope means that helped. Maybe a calibration every month might do the trick? Thing is, even today, the battery is still giving me random estimates, half an hour ago it was at 4:00 and now it's up to 5:45 and I'm doing the exact same stuff. Do you think it's worth it to take this mac to a repair center? Thank you, guys! PS: I'm running El Capitan. I haven't done a reinstall since I first bought the mac, maybe that would help?