Stereo installation

[murari@umiacs.UMD.EDU (Murari Srinivasan)]

I'm trying to install this new Blaupunkt
into my 5k. The Blaupunkt has three power
related wires :

1. power (8A fuse) to be connected to ignition
2. Battery (3A fuse) 
3. Ground.

The 5k has wires for (1) and (3) above, i.e..
the power wire which runs into the original
stereo comes alive when the ignition is turned
on, and of course, there is a ground wire.

My question : Does the wire on the Blaupunkt
marked "battery" go directly to the positive
terminal of the battery ? 

Are there any dangers associated with this ?
(The stereo is not very high power..12W rms x 4)

Any reason why the stereo would need to be wired
directly to the battery when it already has a power
connection through the ignition switch ?

I know...all this is not really Audi related, but hey, 
who else could i ask :)

Murari
85 5k.