For me, the period from July to September is only three months, so that should be well into the warranty, even the limited warranty of a battery. That's the fix: get a free new one.
I bought my laptop in July (so its about six months old). Only recently, the battery will not charge all the way. Everytime you drain the battery, it will recharge one less percent (ex charged at 79% one time, drained it, and recharged it and would only charge to 78%.) What would cause this and is there a way to fix it?