I had my previous battery for about 4 years. I replaced it with a Nupower battery when I started getting charges of up to 88% and it would die in about an hour. I went with Nupower (bc I don't like to give Apple my money) and they advertise 5% more battery life. I have been unable to get it to charge to 100%. It stops at 99% and lasts about 2 and a half hours of just regular internet reading (no special programs, videos, etc...). I am wondering if I have a defective battery and if it should last longer?