Shutting It Off

[Bobbyhotrods@comcast.net]

So the little man who works nights in my head awoke me to the news that my 
battery switch won't shut off anything except the battery with the alternator 
downstream. I inquired to a pal the best solution, a four pole switch from 
Longacre, $28.
It arrived today, and as I started to change things out, I wondered why I 
simply couldn't run the big wire from the alternator to the + side of the 
battery directly, upstream of the battery switch I have now. 
What am I missing? Thanks, BJ