Converter Replacement - Be Careful with DC Hook-Up

[BCam]

I just replaced the converter/charger in my 2002 Itasca Suncruiser 35U with a multi-stage converter/charger and discovered that the wire connecting the positive terminal of the converter to the battery is black, not red!

I'm partially color blind (often confusing red and green) so I assumed I had a large black wire = Neg, a large red wire = Pos, and a smaller green wire = ground. I'd already disconnected the battery and the old converter.

Wrong! After I hooked everything up and plugged in the converter, I blew both 40 amp fuses on the converter.

After disconnecting the converter, I reconnected the battery and checked polarity with my multimeter. I had my wife look at the wire colors and what I thought was a large red wire and a smaller green wire was actually two red wires. Black = Pos, Large Red = Neg and Small Red (not green) = Ground.

To make things even more confusing, Winnebago's wiring diagram for my 2002 35U shows a black = pos and two greens, one for neg and one for ground.

After replacing the fuses, the converter seems to be OK so I've reconnected everything and it's putting out the correct voltage and not blowing the fuses. I'll check later to see if it's stepping through the stages.

I'm not new to DC circuitry, having owned several sailboats, a trailer, numerous vehicles and, to top it off, I'm a Ham radio operator. I know I should have checked everything out with a multimeter first (or had double-checked when I disconnected the old converter) but I still think Winnebago should have used Red = Pos, Black = Neg and either Black or Green for ground. And why they used two reds instead of the two greens specified in their schematic is beyond me.

I didn't check the wiring diagrams for any other models so be careful, your's may be different. To avoid any future issues, I'm marking all three wires with tape and a Sharpie as to their function.

 

[70ChevelleSS]

Well I can see how you were confused. Typically it's red and black for positive and negative. Or Black and white for positive and negative in RV DC wiring. Would be nice if they could be consistent.

 

[BCam]

To make things even more confusing, the connections at the batteries are the traditional red = pos and black = neg but most of the DC circuits in the motorhome are yellow = pos, white = neg/ground.

 

[old_engineer]

I'm not sure there really is a standard just a bunch of conventions that are randomly used by the RV manufacturers. I haven't opened up our Micro Minnie but it is the usual red+ and white- from the battery. At some point I plan to open up the junction box and get behind the converter to check things out. On our old non-Winnebago trailer it was red and white from the battery. Then switched to black+ and white- inside the junction box where the umbilical connected to the trailer wiring.

 

[BCam]

Every car or truck I've owned has red+ and black- connecting to the battery, I've never had a white ground on a vehicle. IMHO that convention for connection to the battery shouldn't be messed with by any RV manufacturer. At a minimum, red should always be positive.

Once inside the coach, pretty much anything goes, except I think that any wires going to the battery for charging purposes (converter, solar, etc.) should follow the red+/black- convention.

 

[old_engineer]

Keep in mind an RV is not classified as a vehicle but as a dwelling. I think the black+ in RV's has to do with the fact they also have AC circuits where black is hot and white neutral. By keeping them both the same color makes power color coding consistent regardless of source. As to the battery being red+ and white- that is complying with the National Electrical Code for 2 wire grounded DC. Using red+ and black- would indicate and ungrounded 2 wire circuit or possibly a 3 wire grounded circuit.

 

[BCam]

Thanks for the info. Nonetheless, it's still confusing and, as I previously stated, mine is red+/black- at the battery so it apparently is consistent with automotive wiring and not the National Electric Code.

And, getting back to my original point, before connecting anything, use a multimeter to make sure first. Things are inconsistent out there.