Battery trouble??

What is your question?

Hello, i'm working in a ski resort for the winter. So my van did not move since the beginning of december. I didn't disconnect the battery so it's flat. But i'm charging it this 2 days and i am still not able to start the van. While it's charging the hazard light are flashing for a minute then stop for a fews minutes et does it again. Is there someone who know when i can't start my engine??