I see there are a number of questions regarding this but none made it clear to me, so I'll risk being virtually stoned and go ahead and ask it again.
I have a 12V battery which powers some 12V components, however I also have a bunch of other components that require 5V, so I will get a buck converter. On it there is a Vin+, Vin- as well as Vout+ and Vout-. My 12V circuit has only a + wire, the - is connected to ground (which happens to be the metal case of my work), so I have 12V + wire going into Vin+ on the converter and Vin- is connected to ground. On the other side I would like also to have Vout- connected to ground so that it's easier to connect my 5V components without having to deal with wires but it's bugging me because I'm essentially connecting Vin- and Vout- on the converter and if that was okay then why would they even have put Vout- on there?