[eagle]

I use that brand power coverters all the time at work, for 24 to 12 volt conversion. However, I have never checked to see if the secondary is isolated from the primary. Simple enough to check. If you are planning on running a car radio or CB they both have negative ground to case/chassis so you will need isolation. If you are just planning on running a cigarette lighter, then its simple to just isolate the lighter. As far as your question how to wire positive ground input, Yes, Positive must go to red wire, negative to black. Doesn't matter which you use for ground, red is ALWAYS positive side of battery. And as far as not fused input, supply your own. Simply wire a fuse on the input side of the converter, I usually fuse at 2x the expected load or 1x the maximum load, whichever is less.