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Fridge Relay


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#1 k9kfd

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Posted 17 July 2010 - 12:06 PM

Hi Kelly
S5 Wyoming 2006

Can you confirm that my caravan has a relay which detects the ignition on supply to the fridge from pin 6 to enable battery charging only to take place from pin 4 (permanent live) when fridge is on i.e when the engine is running. I only ask as some 12s diagrams show pin 2 (Blue) as ignition on battery charging or as spare terminal. Many Thanks

#2 BrianI

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Posted 17 July 2010 - 12:12 PM

Yes that will be the case as pin 2 is no longer used since 1998.

You can easily check as the same relay turns off all other 12v supplies in your caravan.
So, with your caravan connected to the car, switch on an internal light.
Start your car engine and the light should go out.
You may also hear the relays click if you are in the caravan

This link shows the difference between pre 1998 and post 1998 wiring
http://www.volvoclub...electrics.shtml
Brian

#3 k9kfd

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Posted 17 July 2010 - 01:52 PM

Hi Brian, thanks for the fast reply . Staying in the caravan overnight at the CC in Whitstable, all hooked up for an early sailing from Dover - Tried starting the car only to find the battery was flat or not enough “Oomph” to turn over the diesel engine ADAC came to the rescue and we managed a later boat, but I did feel very foolish as I surmised (wrongly according to your kind reply) that we had depleted the car battery somehow via the 12s plug. The Sorento has a fairly heavy duty battery yet I still somehow managed to flatten it! Next time I think I will leave it unplugged for a less stressful start to holiday!

Yes that will be the case as pin 2 is no longer used since 1998.

You can easily check as the same relay turns off all other 12v supplies in your caravan.
So, with your caravan connected to the car, switch on an internal light.
Start your car engine and the light should go out.
You may also hear the relays click if you are in the caravan

This link shows the difference between pre 1998 and post 1998 wiring
http://www.volvoclub...electrics.shtml
Brian


Edited by k9kfd, 17 July 2010 - 01:55 PM.


#4 BrianI

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Posted 17 July 2010 - 01:56 PM

With your caravan connected to the car, you are running the caravan off the car battery. You must have used quite a bit of power to flatten it though. To run off the caravan battery you need to unplug it.

See para 3.4.1 from 2009 model manual. Yours will be similar

http://www.bailey-ca...iley_Manual.pdf

Brian

#5 k9kfd

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Posted 17 July 2010 - 02:11 PM

Cheers Brian - I won't make that mistake again!!
Keith

With your caravan connected to the car, you are running the caravan off the car battery. You must have used quite a bit of power to flatten it though. To run off the caravan battery you need to unplug it.

See para 3.4.1 from 2009 model manual. Yours will be similar

http://www.bailey-ca...iley_Manual.pdf

Brian



#6 Steve W77

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Posted 17 July 2010 - 02:50 PM

With your caravan connected to the car, you are running the caravan off the car battery. You must have used quite a bit of power to flatten it though. To run off the caravan battery you need to unplug it.

See para 3.4.1 from 2009 model manual. Yours will be similar

http://www.bailey-ca...iley_Manual.pdf

Brian





Sorry, but that is not correct, once the ignition has been turned off the habitation relay disconnects the caravan from the car. If this is not working correctly, you either have a wiring fault or a faulty habitation relay.




Steve W

#7 BrianI

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Posted 17 July 2010 - 04:18 PM

Sorry, but that is not correct, once the ignition has been turned off the habitation relay disconnects the caravan from the car. If this is not working correctly, you either have a wiring fault or a faulty habitation relay.
Steve W

Steve
Can I suggest you read the reference in the Bailey manual quoted in my post above para 3.4.1, which says quote

The system is fitted with an automatic relay to select the power source. When the car is connected via lead the car power will be used. When the car is not connected the battery and or the power supply will be used to power the caravan.


The evidence in also in K9kfd's post where his car battery was flattened by leaving the caravan connected to the car.

Other manufacturers carvans operate in a similar way although some have a manual car/caravan battery selector switch

Brian

#8 Steve W77

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Posted 17 July 2010 - 04:53 PM

Steve
Can I suggest you read the reference in the Bailey manual quoted in my post above para 3.4.1, which says quote



The evidence in also in K9kfd's post where his car battery was flattened by leaving the caravan connected to the car.

Other manufacturers carvans operate in a similar way although some have a manual car/caravan battery selector switch

Brian



The whole point in having a habitation relay, is exactly so you do not have to remove the connector, once the ignition is switched off, the relay drops out and reconnects the caravan battery and all the internal 12 volt supply to the caravan. As far as I know, this comes under the construction and use regulations and all caravans after 1998 should be wired this way. I can only assume that the Bailey mannual has assumed that the ignition would be on once the the car was connected. This relay is a safety device to isolate the caravan whilst on the move, thereby reducing the risk of fire due to short circuits in the caravan whilst being towed. Once the car is disconnected by switching off the ignition then power is restored the the van.



Steve W

Edited by Steve W77, 17 July 2010 - 04:56 PM.


#9 BrianI

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Posted 17 July 2010 - 05:17 PM

Steve,

This is the way it works.

1. Caravan connected to car, engine off.
Power supplied to caravan from car battery
2. Caravan connected to car, engine running
Power supplied to fridge, and caravan battery connected to allow charging. All other 12v supplies in caravan isolated

The Bailey manual is correct and does not assume the igntion is left on as in this case you would get no 12v power.

Brian

#10 Tigger

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Posted 17 July 2010 - 06:24 PM

I sometimes have to switch to a second battery on a rally. Presumably I could make up a wire from the spare battery to a 12S socket (I have a box for the battery), rather than the hassle of swapping the batteries?

I'm guessing I wire +ve to pin 4, -ve to pin 3?

#11 BrianI

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Posted 17 July 2010 - 06:40 PM

I sometimes have to switch to a second battery on a rally. Presumably I could make up a wire from the spare battery to a 12S socket (I have a box for the battery), rather than the hassle of swapping the batteries?

I'm guessing I wire +ve to pin 4, -ve to pin 3?

Yes thats correct but run it through a 20amp fuse.
Alternatively if you have flattened your caravan battery, could could just simply plug into your car which will then run off the car battery. Obviously you could not do this for a long time as you would not want to flatten your car battery but it might be a short term solution. It would thus enable you to run, say, your hot water heater on gas. The control circuit for these relies on a 12v supply which cuts the heater out when the voltage drops below a certain amount.

Brian

#12 RichardBrown

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Posted 20 July 2010 - 02:26 PM

With your caravan connected to the car, you are running the caravan off the car battery. You must have used quite a bit of power to flatten it though. To run off the caravan battery you need to unplug it.

See para 3.4.1 from 2009 model manual. Yours will be similar

http://www.bailey-ca...iley_Manual.pdf

Brian


I agree, it does seem strange that you flattened your car battery just be leaving the caravan connected. Did you leave a light on or something? I'm assuming it wouldn't have been the fridge because am I correct in thinking that the fridge is ONLY powered by the car battery when the ignition is switch on, otherwise no power is sent to the fridge?

Richard

#13 MalH

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Posted 20 July 2010 - 02:29 PM

I've had a couple of instances of the relay sticking in the on position, thus leaving the fridge connected to the car battery when the engine has been switched off. Luckily with the Thetford fridge there is a warning light so I was able to disconnect the cable and avoid flattening th battery.

#14 jaymac

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Posted 20 July 2010 - 03:32 PM

I've never been quite sure of the situation regarding the fridge when hitched up to the car. I thought it might drain the car battery when stationery so I've tended to switch it off when travelling. So if I'm understanding this correctly this shouldn't happen and I can turn the fridge to battery when travelling without worrying about flat batteries, yes?

#15 BrianI

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Posted 20 July 2010 - 03:40 PM

I've never been quite sure of the situation regarding the fridge when hitched up to the car. I thought it might drain the car battery when stationery so I've tended to switch it off when travelling. So if I'm understanding this correctly this shouldn't happen and I can turn the fridge to battery when travelling without worrying about flat batteries, yes?

Yes. There is a relay in your car that controls this and provided it is functioning properly, it should switch off when you switch the ignition off. The problem is these days that many fridges do not have a light indicating they are on so it is difficult to tell whether they are on or off.
Brian

#16 RichardBrown

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Posted 20 July 2010 - 07:44 PM

Yes. There is a relay in your car that controls this and provided it is functioning properly, it should switch off when you switch the ignition off. The problem is these days that many fridges do not have a light indicating they are on so it is difficult to tell whether they are on or off.
Brian


I agree, it is difficult to know if the fridge is on or off - mine doesn't have a light, a real pain!! Would it be correct to say then that after switching the ignition off, if it were still possible to switch the lights on in the caravan, then that would mean that the relay is working since it shows that power has been switched back to the caravan battery. If the relay is not working properly and there is still power to the fridge, then presumably it would not be possible to switch the caravan lights on. Correct?

#17 BrianI

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Posted 20 July 2010 - 08:07 PM

I agree, it is difficult to know if the fridge is on or off - mine doesn't have a light, a real pain!! Would it be correct to say then that after switching the ignition off, if it were still possible to switch the lights on in the caravan, then that would mean that the relay is working since it shows that power has been switched back to the caravan battery. If the relay is not working properly and there is still power to the fridge, then presumably it would not be possible to switch the caravan lights on. Correct?

Yes that would be the situation. Not thought of that.
Brian

#18 k9kfd

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Posted 21 July 2010 - 09:09 AM

I agree, it is difficult to know if the fridge is on or off - mine doesn't have a light, a real pain!! Would it be correct to say then that after switching the ignition off, if it were still possible to switch the lights on in the caravan, then that would mean that the relay is working since it shows that power has been switched back to the caravan battery. If the relay is not working properly and there is still power to the fridge, then presumably it would not be possible to switch the caravan lights on. Correct?

Unless you’re draining the car battery via pin 4? Which it seems I did!




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