About the whole battery issue.

Okay so I got a dell as a present last year around november as a gift, it was brand new, I was even there when they ordered it.. So my computer is almost two years old but no quite . I take really good care of my computer and always make sure that I dont overcharge the battery and leave the plug in. Today I check and my battery life on dell support center because it can tell you that there. It says my battery life is fair and its in the yellow section, green being the best battery life of course and red being the worst. So its right in the middle. I should have a good battery for at least 3 years. So I'm not really sure why it says my battery is in fair condintion. Also my brother has a dell that was also bought with mine, same computer and everything. His battery says that soon he will have to buy a new battery for his computer. Both of our computers arent even 2 years old, this doesnt make any sense. A new battery costs 180$ and we shouldn't have to buy a new one for a practically new computer. I'm not sure what to do, and when I buy/get a computer, it should work for a good 3 years not work for 3 years and have me have to buy a new battery every year. This is ridiculous.