I don't know of any standard for low voltage DC wiring... Doesn't mean there isn't any though. 

I would recommend you stay away from using white,black & green.  There IS a color code for AC 120 volt wiring that calls for the black to be "HOT"  white to be "Neutral" and green to be "GROUND"

Could be very confusing(mixing AC and DC power), expensive (burned up stuff) , and dangerous (Electric shock to sensitive body parts)...

lol, here's the story.

we goofed and left the LQ unplugged and the D/C master switch on: drained the battery dead. Too Dead. Had to replace it. LQ (by JBJ Conversions in GA) is done in black and white wires. Husband pulls old battery, replaces it with new one, puts black and white wires where they belong.

Funny, none of the sensors want to work. huh. Need to get on the road, so we do, we'll figure it out later. Later, I open the 12V plug-in cooler, which has a switch to allow you to make it a heater. That sucker was hot. I thought I'd stuffed it too full and impeded the blower. I rescued my food, unplugged cooler, and we stood there scratching our, ummmm, heads.

Finally, it hit my husband. The cooler had reversed polarity. He opened the D/C panel cover, dug around...yup, the wires were backasswards. Nice. Turned it all off at the master switch, swapped the battery around to the 'wrong' set up, and poof, it all worked.

Oh, btw, my husband is a Master Electrician. 20 years experience. He was following the basic protocol you use with any D/C set up, like your car battery: black is ground, red is hot. So, if using black and white: black is ground, _____ is hot.

Check your set up before you swap batteries and let your cooler cook your beer . Just double check you aren't messing up your party.