Well here goes my first proper question: I managed to snap the fan belt last Tuesday and for the past week I've been just using the Moonraker off an on for making cups of coffee, listening to music on the stereo (for about 20 minutes in total), and lots of coming and going and sometimes keeping the dome light on for 10 minutes, etc. My local mechanic was busy until tomorrow so I thought I'd just get to know my van without it moving

Just now, I tried to see if it would start so my mechanic could at least drive it down the road to his place, but despite the initial attempt making a kind of starting noise and turning, any attempt after that just did nothing - not even turning. There was a hum/whirring sound, lights went dim. Battery is dead, right?
So my question is, would a week's worth of what I described above flatten it? Plus, I told my mechanic the battery was flat and he said, "ah, the fan-belt must power the alternator". It's his first time with a van, but is that right? I'm not checking his knowledge - he's awesome - just wondering!
Thanks for any info

PA