wishaw, I dont fully agree with that.
If you have a really flat battery, the altenator will not be able to produce 14.5Volts at the battery terminals, you will find as the battery charge level goes up, the voltage will eventually rise - but this takes quite a while. Its not uncommon to see an altenator putting in 12.8 volts and it may rise to 13.2 volts and stay their for a while.
You will only get maximum voltage being produced when everything is in top working condition. The battery is a crucial element that makes up the charging system. Its funny you know, I get old blokes coming in saying that once a car is running you can pull a battery lead off to make sure the "generator" is working..... Not these days Once you loose your field power the alt will stop charging. Once they work figure out Perpetual Motion, you will only need a battery to start it.
Cheers
Sumo