Morning all

Now i'm a little concerned, went to start the ole girl up yesterday after not being driven or started for a good 4 days and low and behold she would not start or trun over

My mate came over with some jump leads, wacked them on and away she went!!!!
Took the ole girl for a quick spin and filled up with some derv, parked up till this morning, got in it this morning and it started ok with no probs.
So after only 4 days of rest would the battery go flat??

I dont know if it's the origianl battery......
Any other ideas?
Ta..