Battery + to Inverter + & Inverter - to Car Chasis Ground? (Not Battery - ?)

lolcashcow

Hi Guys,

I gathered up everything for my installation of the inverter in my electric car. I am doing this same installation shown here: http://www.mynissanleaf.com/viewtopic.php?t=13097



One thing I noticed is that the Battery + ends up connected (After going through the breaker & Anderson Plug) to the Inverter +, but the Inverter - is NOT connected to the battery - it is actually connected to the car Chassis Ground. The inverter, a xantrex prowatt 1000, has 3 connection points Positive, Negative, and Chassis Ground. Here is a picture I found of the rear view of the inverter. note that this isn't the one being used in the electric car the picture below is just for reference on how the rear looks like:



I'm a noob at this sort of thing, but is it safe to not to connect the Negative ( - ) in the inverter to the Negative ( - ) in the Battery? Instead to Connect the Negative of the inverter to the Chassis Ground of the car? That means the connection on the inverter labeled as "Chassis Ground" is not even being used.

Here is the part in that thread that speaks about the ground connection:

"The ground is run to a CAST copper fitting, attached to the "spare" ground hole in the inverter housing with a 5/16" SS Nut/ Bolt/ Washer, with a "Holesaw Made" 3/4" X 1/8" lead crush washer and covered (tastefully) in electrical anti-corrosion goo. "

I'm kind of confused on this part of the installation. You aren't supposed to attach anything to the negative terminal on the battery because there is some sort of sensor that measures the state of the battery. The battery is recharged with a dc to dc converter the electric car has.

When it says inverter housing? is he actually talking about the inverter? I just can't see the connection clearly. If so does this mean there is an extra cable being run along with the regular battery negative connection in the inverter?


My set up will be:

The inverter:  Xantrex prowatt sw2000 (1800W continuous 3000 Max Surge)
Copper Cables: #4/0 AWG (Cable length will be kept under 2 feet long)
http://www.amazon.com/Blue-Sea-Systems-5191-Terminal/dp/B0019ZBTV4
Blue Sea Systems 5191 Fuse Block Terminal 30-300 AMP 
http://www.amazon.com/Blue-Sea-Systems-250A-Terminal/dp/B0026KY6R0
Blue Sea Systems 250 AMP MRBF Terminal Fuse
Anderson SB350 Connector up to 450 Amps

I will be running currents of around 1200 watts for I think 20 minutes or so. Other times I will run less probably for around the same amount of time. I just want to know if installing the inverter this way is safe because well the Negative in the battery is not being used and the ground on the inverter isn't being used.