you gotta ask WHY is the battery flat?????
Good question. The battery is about a year old. My missis got it, I told her to get a high ampage one. The cars not been used much this week. Maybe its beacause I jumped in the car with heated seat on heated front and rear window on and the blower going, and did't drive it that far.
But still, The car did not even turn over when it would not start again. With a 120amp alternater I woulld of thought it would cope with this.
battries( so i am told) are only meant to last 2years(design life).
also, have you checked the battery leads? on the p38(at least on mine) the clamp is a circular type and is tapered to fit on the tapered post of the battery. as i said before mine popped off, it had also flashed up some errors and beep beforehand but i did not associate this with the battery lead bieng loose. there were no other 'obvious' signs of it bieng loose!!
check that the clamp is fully down on the battery post and tight!!!