E34 bmw cut out and died last night

Hi there, Last night my e34 535is died when i was driving it, all the lights on the dash started to dim down and the abs light came on and things continuously dimmed and electrics started to turn off until the car shut off. We roll started it and it went for another 30secs or so before doing the same again. Then we jump started it and it lasted about 1minute before doing the same again and its now stranded in remuera haha.
- Before this happened one of my belts had been slipping a few times a week, needing me to turn the car off and back on to stop the horrendous noise of the belt slipping.
- The light on the battery is still green so the battery appears to be ok.
- You can still operate the stereo, windows etc when the cars off.
- If you turn off headlights for example the dash lights become brighter
My feeling is that it would be the alternator, but also wondering whether a ground issue could cause this. Any advice is appreciated.

Is this a Singapore import! Not a helpful question I know but am just curious.

Your first clue to get it looked was the belt noise. Is the belt still there!
If it is, then probably alternator.

When i looked in the darkness last night the belts both appear to be intact, do you think the belt may have loosened enough to not be engaging with the alternator anymore! Or maybe the alternator itself has carked it! Another thing to mention is that probably 3 or 4 times before the car actually died i could notice it starting slower and slower like it was running out of battery. And not completely sure as far as i know its out of Germany.

These are very sensitive to battery voltage. Get the battery fully charged before you do anything else. Check that your belts are tight so the alternator is doing its job. The battery may be on its way out.
Check this forum out, do a search or ask here:
http://www.bimmernut.com/forum/5-series-bmw/