pajero wouldnt start and just clicks had aa out and they said it was the alternator but tried car over weekend and it started first time. tried this morning and just click had to have a jump start to get going.
The problem is most likely the battery. It sounds as though it might have a dead cell, or have what is called a "surface charge". This describes exactly what you are talking about. Something you can do to test this at home is this:
Check the voltage of the battery while the vehicle is running with a multimeter. What you are looking for is if the battery loses voltage while the engine is running, it would be a sign the alternator is bad (ie: initial voltage reading is 12.45vdc and continues to drop). If, however, you get normal running voltage (13.1-14.5vdc), the problem lies with the battery.
Had a similar problem with my Pajero (1992 Turbo 2.5D). Replaced the battery and the problem went away for a couple of days but started occurring again, especially on cold starts early in the mornings. One thing that bugged me was that if I attempted to push start it, the starter suddenly fired up just fine if I killed the engine and attempted to start it again.
That got me going that a sudden jerk seems to solve the starter issue everytime. I disconnected the battery and took out the self-starter switch and opened it up. The armature coil was completely covered with carbon and there was no prominent contact point left. It seems that a sudden jerk would somehow disperse some of the carbon layer and starter would fire up, but most of the time that was not the case.
Solution : Try cleaning the contact points with some sand paper. Avoid using a too fine one so as to not ruin the coil itself. For more details, take a look at link here. Its got some pictures as to how to clean it up yourself.