Strange box thing with a light on it.

[Ianburtoncamera]

Hi

I own a 2001 Bav 40. I've lots of questions I can't find the answers for but I'll start with this one.

Does anyone know what this is? (Picture attached) It is actually a junction box, I googles the name, but what I find on google is just a junction box, and doesn't have the switch or the red light on.

It is mounted under the companionway steps on the access door for the engine, it has a cable coming out the back that I think is wired into the alternator.

The light comes on when you throw the switch, regardless of whether the engine is running or not.

I've owned the boat since February and the last owner didn't know what it did either.

Thanks in advance.

[Lyra]

This does not look to me like an original installation.
It would be helpful if you traced the wires exactly to whey are connected.
Of the top of my head I can think of it as being a workaround to one of two problems that may happen on an alternator:
1. An alternate circuit to provide initial field excitation. Normally this is  sometimes done through the low oil pressure circuit, so maybe somebody made this additional circuit in case of failure in the main circuit.)
2. An alternate circuit for a faulty regulator. There is  workaround using a light bulb (or more) as a makeshift regulator.
Of these two it is more probable to be the first one (if at all) since the second option requires a more substantial wattage bulb

[Ripster]

Not much help I'm afraid, but what I can tell you is that is extremely unlikely this was fitted by the factory.  Newlec is a UK brand of Newey&Eyre who I used to work for many years ago.  The box you have is a standard building/electrical industry junction box waterproof to IP65 (as it says on it) The light and switch have been added and will not have come with the box, so someone has assembled this as a kit for something. 

[ITIL MAN]

Might be worth checking the charging voltage with the switch on then off.  A marine electrician commented that I had a high powered alternator fitted to mine and on some smaller boats it would use quite a lot of power from the engine that some fit a switch that disconnects the alternator from charging. Your switch is certainly not standard and as people do like to mess around with things you need to start checking voltages around the alternator and see what difference the switch makes, on or off.

[Nigel]

It's a DIY device, to find out what it does you need to trace the wires and check what the switch does.

[sy_Anniina]

I have the same vintage, same model . 3-cabin cruiser that is also for us a new boat with first season ending.

For sure this is not original installation, none of the original electric installations used even remotely that kind of component. Then again any boat of this age for sure has custom installations of previous owners - like ours had red leather sofas, massive LED-lighting, 40-inch flat TV and the best: Sony 6.1 surround sound system  .

Is the light strong enough to be considered as night-sailing stairs light? Just guessing if someone would have been interested in installing red night lighting to the stairs and came up with the closest power source to connect to - the alternator-to-battery wire..

You really have to follow Nigel's advise.

Tommi

[Ianburtoncamera]

Thank you all for the info.

I will check the exact wiring path, but looked like it was the alternator, I will confirm this weekend.

I will get my voltmeter out and take it apart when I am there on Thursday evening.

sy_Anniina, That is a genius idea, I hadn't thought about anything like that, I will have a look and see how bright it is at night.

It is definitly an amature fit as the cable is fairly loose and not what I would have expected from an original fit.

Thanks again and I will report back on Friday.

Cheers

Ian

[Ianburtoncamera]

Solved. I should have taken it apart ages ago, but didnt want to cause more issues by taking something apart before i knew what it was.

It is just a red light and switch, I guess for night sailing, so I think you were right sy_Anniina.

Thank you for the help.

I