Cabin Lighting

[DIW]

I'm easily confused so a simple question !!
Boats a Sealine F33 so when connected to shore power do the cabin lights run off 12v or 240 mains ? I think its 12v because when the water pump is operating the lights dim for a second. /forums/images/graemlins/confused.gif
Ian

 

[VicS]

If you are using the same lights then they are still running off 12V.
But if you have a battery chager on they will in effect be running off the mains via that.
Unless you have complex switching arrangement involving a transformer to supply the lights.

You could install 240 volt lights to run directly off the shore power if you wished.

 

[roly_voya]

That usally means the water pump is on its last legs, its struggling to get up to full presure so drawing exsesive current. It should purr up to pressure the crisply shut off not go clunk clunk for several slow cycles

 

[john_morris_uk]

It could mean that - it could also mean lots of other things. For example we have no data about the charging system on the boat so it could be that the battery is dying and the charging system can't keep up and the battery volts drop under the load of the fresh water pump even when charging is taking place. It could simply mean that the wiring is undersized to the main distribution board and the load of the water pump drops the voltage a little. It doesn't take much voltage drop to notice a slight dimming of the lights.

My money would be on a low power charger and a dying battery, but I am not a betting man and it might just as easily be borderline wiring sizes chosen in the build.

I am not sure about condemning the water pump...

 

[VicS]

The question was not about why the lights dim when the waterpump operates but about whether the cabin lights are still operated from the 12volt system when shorepower is connected.

I was a bit vague with my answer because i know nothing about the boat. Ok I recognise the name Sealine and i guess, but only guess, that its a 33ft mobo. I still know nothing about the standard of luxury and sophistication of its fit out. In the absence of any info that would suggest otherwise I'll stick my neck out and say that the lights are definitely still operating from the 12volt system when the shorepower is connected!

Why the lights dim when the pump operates is another matter. IMO it'll be due to a poor connection somewhere in the wiring between battery and panel or in the panel itself. Only careful testing with a voltmeter is likely to locate it. It might, I agree be due to a dodgy pump but I would think that less likely. It might be the battery getting towards the end of its life. If it's a whacking great pump that is capable of supplying the galley tap and a couple of showers simutaneously then it may be something that cannot easily be avoided.

If everything works OK then there may be no point in pursuing that any further anyway.

 

[john_morris_uk]

I agree with you Vic - but my post was in response to Roly-voya's side remark that the pump was probably on the way out. I was trying to stop the planting of a possibly (probably) false idea in the original poster's mind.

 

[rogerthebodger]

The answer is your lights do run off the same supply os the pump. If it is 12 VDC the dimming of the lights is not due to any fault but due to the fact that a 12 Volt DC motor on startup is a direct short across the supply and will draw a very large current for a very short time thus pulling down the supply voltage.

Tha amount of dimming will depend on the impedance of the supply weather supplied by battery mains transformer / diode or both.

The point to note for VicS and John is
[ QUOTE ]
when the water pump is operating the lights dim for a second

[/ QUOTE ]

which IMHO says it all

 

[john_morris_uk]

I don't disagree - but I thought that is what I said in the first place?