idling with pulleys, how long before battery dies???

[jetuomi]

let me add, the reason I'm asking is that I warm the car up in the morning (7am) when the frost up here in Canada is still on the grass. (haha, j/k)

But seriously, if it idles for 10 minutes, and then I drive it for 1/2 hr, there should be no problems when I park it and go to start it 8 hours later, right??

Thanks !!