Got a email from one of the reader. Can you guys help him?

"

i own HP pavillion DV4 2106 tx. I am facing a problem related to my battery,

In battery notification area a red cross is blinking over battery icon and message is there "consider replacing your battery. there is a problem with your battery so your computer might shut down suddenly"

please help me as the battery back up has been reduced to only 30 minutes,earlier before i callibrated the battery it was more than 2 hrs.
But still Hp support assistant shows battery health as 'GOOD'.

"