I have a 2014 MBP 15 (purchased new) and cycle count is 356 but battery life is fine when I'm mobile. I also have a 2015 MBP 15 and the cycle count is 345 and battery performance is fine. The full charge on the 2014 is 6,814 mAh and it's 6,771 on the 2015 so the 2015 was used more heavily (I bought it used two years ago). If I got a used system with a bad battery, I'd just replace the battery.