El captain update ruins battery life!!!!

Hello,

I was just wondering if someone could help explain this issue to me. I have become beyond frustrated with the battery life of my mac. Now, to make things clear, my Mac is still brand new, taken excellent condition of it, charged it the way apple recommended, and much more. I have made sure that no application is consuming a large amount of energy before i posted this. My battery life was once upon a time 10 hours long, however, after updating to El Captain a week ago, I noticed that my fan was working extra hard to keep up and the length of the battery, off charge, was ONLY 4 HOURS!!!!! I am extremely frustrated and annoyed, I tried calling apple and I found that they were little help, so I would really appreciate it if someone could help me. I am not blaming anyone or anything, but i would just like to know if this issue will soon be fixed or if I will have to take it to the apple store, which would be beyond inconvenient, as I have multiple assignments to do, whilst on the go.

Thank you.

P.s. to make things extra clear, I only run one app at a time, I am currently on 21 cycles and the battery condition is normal.