cobyoshi

Hi resently bought a p100 1.8 td.It seemed to run fine untill i pulled up for a few minutes came back tried starting it and all i can hear is a clicking sound, I am guessing thats the starter but it does try to turn over a slight bit but nothing close to starting it.And the battery seems to die away and then its just a clicking sound.I am thinking could it be the alternator. Or i did spot the last owner used a round poled battery instead of a flat poled one. They basically screwed through the plus and minus contections and screwed the screw down in to the poles.I did tighten them but to no avail it still wont start so i am thinking it may not be that. or could it? what else could it be a broken earth?Any help appreciated.