Is there something wrong with my t-mobile dash battery?

i recently bought a t-mobile dash from ebay. It is second hand i think. I read from the internet that the battery life of t-mobile dash is 202 hours but my dash's battery life lasts only for one day or one day and half and I don't do lots of text messaging yet. Normally, I do lots of SMS messaging. I was wondering if there is something wrong with the battery or the dash just eats a lot of battery life? It does not shut down nor anything else. My problem is it has low battery life. Do I need to change my battery or it is only normal for PDA's to have low battery life? Please help me. i am clueless.