Grounding 12v converter?

When hooking up a 400w voltage converter directly to the battery do I need to run the black all the way back to the battery or can I just ground it to the frame? The black on the battery just goes to the frame correct? If I can just ground the black to the frame near under the rear seat the converter I won't induce a bunch of current in my Jeep will I? Shock people and/or have residual current in the capacitors (of the converter) and continue to power things when the vehicle is shut down? How do I do it right? thanks

1. Prep and clean the mating surface so as it is free of any paint. Remember, surface area and the diameter of the ring terminal MUST be reflective of the potential current draw the unit will draw down upon. 2. If there is a choice between using a self tapping screw and a bolt. Use a bolt, as the bolt will not back out due to vibration. It will also not rust as readily as a aftermarket modification. 3. Use a star washer to ensure direct contact to the surface area, this includes when you are using a bolt. The star washer will reduce the amount of residue resistance, and will prolong the contact area, even when rust formation begins. 4. Apply dielectric grease compond to the area, and the bolt / screw. This will promote current transfer, and inhibit moisture, which will cause corrosion. 5. If you insist upon crimping the terminal, ensure you do so properly. Aslo solder the end, to ensure a maximum contact patch with the terminal and wiring. 6. What ever location you decide to use, always try to use the floor, as this provides the least resistence, and will allow you the most current transfer. 7. You will not harn anyone if you ground it to the frame. But use common sense, and ensure you do not allow the wiring to be submerged in any cavity that may accumulate water. Regards EVIL Teken . . .

I've heard that w/ high watt applications I should ground back to the battery.  I'm getting conflicting answers... Anyone else care to comment as to where I should ground?  thanks

Using the battery ground only serves one purpose. That is to ensure the same potential, that is it. If you were to measure the residue resistance from the battery vs the frame, the frame would always have more resistance. So technically it is transfering less efficiently than if you used the negative battery post. But there is a reason why all North American makers have used the negative system. This is to reduce the amount of return wiring to and from the battery. Attach the ground wire to the frame of the floor, you will be good to go. Regards EVIL Teken . . .

I will have to stand behind Teken, I couldn't agree any more than with the information he has given.