Re: Caravan wiring question

[Woody]

"Tom" <m...@privacy.net> wrote in message
news:XnsA19DAE73...@news.datemas.de...
> Hi,
>
> I'm planning fitting a DIY wireless camera system to the rear
> of my
> caravan to allow me a rear view mirror option whilst driving -
> I like to
> see who's behind me and what they are up to. I've got most of
> it sorted out
> but I'm left with the problem of powering the camera and
> transmitter
> inside the caravan whilst towing.
>
> It needs to be 'on' when the car ignition system is on but
> 'off' at all
> other times. I noticed that the Fridge power pin on the 12S
> plug is
> powered up when the ignition is on, but 'off' when the ignition
> is
> off and this would seem to be the obvious contender. However,
> the fridge
> also needs an alternative 12v to keep it running on site, even
> though
> the fridge is a 3-way. If there is no 12v, the fridge will not
> run even
> if hooked up to mains or on gas.
>
> My concern is that if I connect my camera system to the fridge
> power, it
> will result in the leisure battery being drained by the camera
> system
> which will be permanently on.
>
> Any suggestions? The van is a 2007 Swift Charisma, so
> reasonably
> modern.
>
> TAI
>



Methinks you have got a little misunderstanding here.

Firstly the 12V supply to the fridge is purely for the interior
light. It will work on gas or 240V without 12v . As the fridge
cooling draws typically 10A at 12V you would not want it
connected to the caravan battery under any circumstances. In that
case using the fridge supply from the car - i.e. switched - would
not be a problem.

What is a problem is the law. Unless it has been changed I think
you will find thatit is illegal to be able to see a screen
whatever it is showing whilst driving. Any Police car that has a
live camera has the screen angle towards the passenger/observer.
You need to do a bit of research in this area before going any
further.


--
Woody

harrogate three at ntlworld dot com

[Woody]

"Tom" <m...@privacy.net> wrote in message

news:XnsA19DBE137...@news.datemas.de...
> "Woody" <harro...@ntlworld.com> wrote in
> news:kk1glg$as1$1@dont-
> email.me:

> No. Definitely not. Without the 12v, the fridge simply won't
> start. The
> reason I know is that I had one of the infamous Nord chargers
> which
> failed. When the leisure battery dropped below about 11.8v, the
> fridge
> cut off. I asked about in the Swift forum and this would appear
> normal.
> The 12v runs a bit more than just the interior light. A number
> of others
> in the forum had a similar problem with the fridge if the 12v
> disappeared.

>
>> As the fridge
>> cooling draws typically 10A at 12V you would not want it
>> connected to the caravan battery under any circumstances. In
>> that
>> case using the fridge supply from the car - i.e. switched -
>> would
>> not be a problem.
>

> My understanding is that the fridge does connect to the leisure
> battery
> for the purpose of running the electronics, although it can
> also run off
> the 12v for main cooling if needed but, as you say, it won't
> run for
> long before the leisure battery is exhausted. If there is no
> 12v,
> the electronics cannot run and the fridge shuts down
> irrespective of
> whether it is running mains or gas as it has no means to run
> the
> electronic controls.

>
>> What is a problem is the law. Unless it has been changed I
>> think
>> you will find thatit is illegal to be able to see a screen
>> whatever it is showing whilst driving.
>

> Not now. Law has changed and rear view cameras are legal,
> including
> permanently on types. The screen clips over the rear view
> mirror when
> towing.
>
> Anyway sat navs would similarly be illegal.
>


No, a sat nav is not a TV screen - it has the same status as the
speedo.

[Harry Bloomfield]

Tom explained :

> Hi,
>
> I'm planning fitting a DIY wireless camera system to the rear of my
> caravan to allow me a rear view mirror option whilst driving - I like to
> see who's behind me and what they are up to. I've got most of it sorted out
> but I'm left with the problem of powering the camera and transmitter
> inside the caravan whilst towing.
>
> It needs to be 'on' when the car ignition system is on but 'off' at all
> other times. I noticed that the Fridge power pin on the 12S plug is
> powered up when the ignition is on, but 'off' when the ignition is
> off and this would seem to be the obvious contender. However, the fridge
> also needs an alternative 12v to keep it running on site, even though
> the fridge is a 3-way. If there is no 12v, the fridge will not run even
> if hooked up to mains or on gas.
>
> My concern is that if I connect my camera system to the fridge power, it
> will result in the leisure battery being drained by the camera system
> which will be permanently on.
>
> Any suggestions? The van is a 2007 Swift Charisma, so reasonably
> modern.
>
> TAI

There are normally two 12v supplies to a fridge, the 12v always on when
the van is occupied (habitation relay) from the leisure battery and a
12v supply which comes from the car to actually cool the fridge. It is
the latter one you need to connect to - it becomes live when the engine
is started.

It is perfectly legal to have a screen visible to the driver, providing
the screen is for the purpose of driving - not a TV/video/entertainment
system etc..

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

[Harry Bloomfield]

Tom has brought this to us :
> Harry Bloomfield <harry...@NOSPAM.tiscali.co.uk> wrote in
> news:mn.53967dd49a...@NOSPAM.tiscali.co.uk:

> Many thanks Harry. That answers my question, and the subsequent one
> regarding legality. Just to double check - that's pin 6 on the S plug?

Yes..
http://www.motabars.co.uk/basic_tow_electrics.html

[Woody]

"Harry Bloomfield" <harry...@NOSPAM.tiscali.co.uk> wrote in

message news:mn.53967dd49a...@NOSPAM.tiscali.co.uk...

That was essentially the reply I made to the first part Harry,
but the OP insists that the fridge needs 12V on it to work
whether it is actually being run from mains or gas. That's news
to me - is it to you, or have fridges changed that much of late?
He says it needs 12V to run the electronics?

[Chris J Dixon]

Tom wrote:

>As far as gas is concerned, the 12v is definitely needed for the
>igniter, the display and control systems. The only thing the 240v
>feeds is the 240v element in the fridge. The 12v element and all
>the electronics come off the 12v line. If the 12v is lost or too low
>due to a discharged battery, it won't start in any mode. (It's a
>Dometic fridge).

Looks like you just can't stop "progress". :-(

Chris
--
Chris J Dixon Nottingham UK
ch...@cdixon.me.uk

Plant amazing Acers.

[Harry Bloomfield]

Woody formulated on Wednesday :

Some fridges might need the constant 12v just for the gas ignition
system, once ignited, the 12v is no longer essential. Some very modern
and sophisticated ones need the constant 12v to be there all of the
time, to run the electronics and the LCD display.

So as said - there should always be the 12v which is only live when
being towed, fed from the 12S. Likely there will also be the second 12v
supply intended for ignition and etc.. The latter supply may well be
turned off by the habitation relay when the master switch is turned
off, but it might also be turned off when ever the 12S becomes live.

[Woody]

"Harry Bloomfield" <harry...@NOSPAM.tiscali.co.uk> wrote in

message news:mn.5a107dd4a2...@NOSPAM.tiscali.co.uk...

Yes, I did some digging last night. In most cases (the Dometic as
far as I could see) the 12V is for primary gas ignition and on
some models automatic re-igntion if the flame should extinguish
for any reason.

AFAICS whilst there is some electronics in the fridge its sole
purpose is to measure and display temperature but the fridge will
still work without it. IME there is no temperature control when
running on gas, it is on or off. For that matter there is none
when running on 12V either. The only time that there is temp
control on the fridge is when it is running from mains
electricity.

[Chris J Dixon]

Woody wrote:
>
>Yes, I did some digging last night. In most cases (the Dometic as
>far as I could see) the 12V is for primary gas ignition and on
>some models automatic re-igntion if the flame should extinguish
>for any reason.
>
>AFAICS whilst there is some electronics in the fridge its sole
>purpose is to measure and display temperature but the fridge will
>still work without it. IME there is no temperature control when
>running on gas, it is on or off. For that matter there is none
>when running on 12V either. The only time that there is temp
>control on the fridge is when it is running from mains
>electricity.

Older 3-way fridges also had thermostatic control on gas. If what
you say is correct, this looks like another backward step.

The only reason 12 V has no thermostat is that reliably switching
such a dc load is non-trivial, and it is assumed that it will
only be used for comparatively short periods whilst actually
being towed.

[Harry Bloomfield]

Woody has brought this to us :

> AFAICS whilst there is some electronics in the fridge its sole purpose is to
> measure and display temperature but the fridge will still work without it.
> IME there is no temperature control when running on gas, it is on or off. For
> that matter there is none when running on 12V either. The only time that
> there is temp control on the fridge is when it is running from mains
> electricity.

So far as I am aware, all caravan fridges have temperature control
whilst working on gas, be it either electronic or simple mechanical gas
main valve control.

There is no temperature control whilst on 12v, because it is not
needed. On 12v the system is barely able to help hold the temperature
down whilst travelling, so a stat would never operate.

[bert]

In message <mn.e4927dd4a6...@NOSPAM.tiscali.co.uk>, Harry
Bloomfield <harry...@NOSPAM.tiscali.co.uk> writes

I would agree with that
--
bert

[Dougal]

> I would agree with that.

Conversely, I have no problems with 12V cooling. If anything it
overcools when travelling any significant distance. Freezing some of the
contents is possible! If this is unusual I'd put it down to very low
resistance 12V supply cabling.

The gas installation (Electrolux RM120) has no automatic temperature
control. It is up to the user to select the flame size: three choices
with matching cooling effects.

[Harry Bloomfield]

Dougal explained :

The RM120 is a very old model, I had one in the early 1970's i think.