Volt meter installation

[ajk170]

Hi All- I have a pretty basic question about the installation of a volt meter- my gut tells me these things need to be wired directly to a battery to monitor it properly but could I remove my USB and 12 volt station that's in my kitchen and wire a new station in that includes a volt meter? My assumption is it will not read correctly due to something that's wired in-between the docking station and the battery. I just don't want to run a dedicated wire and then fish it through a wall. If it needs o be direct, maybe I can make a waterproof thing and wire it to the battery box.

Thanks!
-Andy