Ford Mondeo not starting

I had problems with the battery on the car where it wasn't charging after being run ie when I switched off she wouldn't start again. That was solved by charging up over night and she ran fine until I took my daughter to school one morning in heavy rain. The distance was about 500 yds and on arrival I turned the engine off and stupidly cleared the windscreen running the wipers without the engine running. Only for a couple of minutes but when I then came back to the car to go onto work the battery was dead. Jump started her ok and drove 9 miles to work but on coming home battery dead again. Jump started ok, drove home, turned engine off, battery dead but windscreen wipers leapt into life. Assumed they were draining the battery but am I right, are the electrics up the creek or do I just need a new battery. Can anyone help please as I'm not in a position to spend much on her at present