Re: [Amel Yacht Owners] "Permanent" on 12v/24v
Hi Gary,toggle quoted messageShow quoted text
I went through a similar experience about a year ago with the nav station wiring. As always, I was impressed by the design, workmanship, and accessibility of the boat. The “permanent” (how easy it is when the English word was directly borrowed from French) Sailor unit was a little mystery, indeed I found it fed the alway hot wire on our AM/FM radio, to store the presets. Oliver was kind enough to elucidate the design for me, below is his note.
SM 240 Aletes
Rock Hall, Maryland; heading for Antigua November 3
Hello everybody, especially the happy SM owners and their tricky and nicely wired nav station!!
You all have three power supplies, located under the nav station, most of them SAILOR, that turn 24V into 12V, for a maximum output of 6 Amps (if you draw more, you blow the fuse inside the box).
One of them is labelled PERMANENT.
This power supply only feeds the auto-radio with 12V. It is permanently wired to the 24V battery set, without going through the main breakers.
Why is that? In order that the memory of the auto-radio is permanently fed and doesn't lose its preset stations.
BUT, you have all noticed that, when you turn off the breaker (NAVIGATION or INSTRUMENTS) in the hanging locker, you cannot turn on the radio. So you might think the radio is NOT permanently fed.
Indeed it is not.
How does AMEL do that?
There are two wires that feed the auto-radio, one feeds directly the memory system from the SAILOR power supply, one feeds the auto-radio through a relay that is activated only when you get power through the INSTRUMENTS breaker.
If you pay careful attention, when you turn on the INSTRUMENTS breaker, you can hear a CLICK noise coming from the back of the nav station, that's the famous relays that allow 12V power to go to the auto-radio. This relay is activated with 24V.
There are two relays one for the 12V positive, one for the 12V negative.
This system is more complicate than on a car because you need to turn 24V into 12V and you don't get negative through the body of the car but with a wire.
If you look at the back of the main breakers, in the passageway, you will find two small wires connected to the 24V positive and negative inputs of these breakers. These wires feed the PERMANENT SAILOR power supply. You will find connectors on these wires that allow you to disconnect the power supply.
In later SMs and the 54s a switch has been installed on the PERMANENT power supply green box, (or behind the wooden board on starboard side of the nav station in the 54) in order you can easily turn it off. Why? this is for those who leave their boat unattended for a while, without a charge possibility (highly recommended) and who don't want the PERMANENT power supply to empty their batteries (which happens within 3 months).
There is a second item which is permanently connected to the 24V batteries and cannot be turned off:
The battery monitor. But this one is permanently drawing less than the SAILOR power supply.
Take your torch lights and chase for the relays and their wirings.
Olivier from sunny Saint-Martin.