Warning Voltage drops on FP Orana
probably Mahe, Liparis? & Salinas
This is an issue I had recently that may be of interest and applies to all? the current
FP models. I apologise for the photo
quality, I had to use a mobile phone/torch and the Orana
is now 10,000 miles away.
On the Orana the power is fed to 4 distribution boxes. On the Orana the first box is in the starboard hull
, the next two are under the sofa (main cabin) and the last is in the port rear cabin
. All are wired in series, so a voltage drop in the first box is a voltage drop in the rest of the boat. If FP joined the last box back to the battery
and made a ring it would be less of a problem! The box has a printed circuit board (PCB) with ten connections (push on/spade) to individual circuits each fused and connected to the main terminals by the PCB.
I was losing 0.75v from the battery
to my first box, so taking the box apart I found the main positive terminal was loose, so I took the connections off. Underneath there is a single
stainless? nut and 6 washers connecting the terminal to a PCB. Looking at the negative terminal there are two nuts. One to hold the bolt to the PCB and the other to lock it. So a nut is missing. Further examination of the postive terminal connection reveals that the connection to the terminal is via an uncoated tinned connection that the nut is tighten upto. So a loose nut creates a large voltage drop. So I checked the rest of the boxes, 1 was lose and 3 weren't tight.
So it may be a good idear to check all these connections. I presume these are stainless nuts and bolts, if so they have only 3% of the conductance of copper (Ref Calder). The maximum current
draw from any one circuit is 25 amp and most are much less. So its not a wonderful system of power distribution relying on the contact between 3 nuts and a PCB board.