Alternator on a 5.0???

[mr j-man]

hey all!
not sure if ive got this in the right thread!

the alt is near new 2mths old
now for some reason there isnt any voltage increase on the volt gauge factory and also an aftermrkt 1 fitted, prior to problem there would be 12v with accesorys on then would sit around 13-14v when driving.
Now it only sits at 12v and didnt realise there was a prob until my batt went flat (twin 10" thermos fitted) then i checked my volt gauge and wasnt up around the 14v as per normal when driving i recharged the batt then went for a drive to sus it out, i held it out and changed gear at 4grand revs then the needles kicked upto 14v and all is good until i turn motor off then it happens again until i hit 4g rpm!
i havent the slightest of ideas of wat the hell has happened nor do i know where to start looking!
when it hits the 4g it definately is working but why wont it recharge at normal operation

if there are any auto sparkys out there or any one that has had a similar prob let me know

thanks

[GRPABT1]

Sounds like the regulator is cactus mate.

[mr j-man]

what would have possibly caused this to shit itself so quick?