How do you know the light is green?

So the 'no charge' warning light came on whilst driving home. This annoyed me, not only because the batter wasn't charging and it was getting dark, but the light is green and it's a light. Surely when your battery isn't charging the last thing you need is an EXTRA light, which ironically went out once the battery died.

Anyway. After an hour on the charger the battery is fully charged, car starts first pull, everything ok, but the battery's not charging.

Alternator brushes are ok and (Burton) VR is earthed ok. My multimeter isn't working so I can't really test anything else, but i'll get a new one in the morning.

However, the theory is that when revved the output at the battery should hit about 14.3 then cut out yes? Is it safe to disconnect the alternator completely and test it's output?

Any other thoughts/test methods?

Instead, to test its output, run a wire direct from the battery to the exciter terminal on the alternator, bypassing the original wire from the regulator, then keep a close watch on the voltage as the revs are gradually increased.
If it's heading for 15 volts, that should confirm that the problem is most likely not with the alternator.

Next step is to monitor the voltage at the exciter terminal with everything hooked up as normal.
At rest/standstill, there should be 12 volts at that terminal and if everything's working as it should, that voltage should decrease as the engine revs rise.

I thought green light was oil pressure.
Sorry if I've go that wrong.
Don