Hi all, well after what has been an expensive fortnight what with the starter motor disintegrating and taking the battery out with it, it would seem it put too much strain on the alternator, which decided to pack up on me last night.
Left work at 10pm and 2 minutes or so later the dreaded light shows up on the dash, so it's quickly into test mode on the radio and sure enough the voltage is reading 11.6v, so switch of phone charger, fans everything except the lights and speed up a little, luckily there wasn't too much traffic about that time of night, got home 20 minutes later with the voltage just dipping to 10.9v as I turned into the drive, never used my indicators once etc!.
So out with the battery an on charge overnight.
This morning quick check, charged battery and the multimeters out.
The alternator is chucking some current out but not enough to keep the battery topped up.
It is a DENSO unit because you can read it in the moulding of the black plastic cover at the back of the alternator so, search the forums, and in the How to section I came across this link http://www.absolutely-starters-alter.../vauxhall.html
I spoke to a very helpful man called Andy who confirmed my suspicions, the rectifier was most likely shot.
He then proceeded to talk me through how to remove the alternator which is covered in the How to : http://www.vectra-c.com/forum/showthread.php?t=92987
My background is Electronics and I'm a multiskilled engineer with Electrical bias so I have just ordered the rectifier unit itself for under £30 all inc.
Andy also stated that you can actually replace the rectifier with the alternator still in the car, so guess what I'll be attempting this weekend?.
I will post back how I got on, ideally with pictures.