why is the battery in my peugeot speedfight draining of power ?

I bought a speedfight 1 100 a couple of months ago and it wasnt starting, I got it up and running then the battery died so I bought a new one, worked fine. did'nt ride it for a few weeks and the battery was dead. What can be draining it when nothing is in use ? Also I am, having problems with my lights, indicators and brake light works but no side, dipped or full.