Cooling fridge question?

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Jul 18, 2017
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I'm not sure why people are so worried about caravan fridge operation whilst towing.

Surely whoever fitted the towing electrics will know perfectly well what is required and fit accordingly. It amazes me to think that some feel a professional tow-bar fitter doesn't know his/her job! I would expect a few disgruntled customers making their views known if the fridge did not perform adequately.

I would also imagine that everyone turns their fridge on (if possible of course) at least 12 hours prior to beginning a journey. If they don't then I respectfully suggest they should.
We've never had a problem with any fridge and that includes overnight ferry travel as well as towing in the upper 30ies in Europe.

I imagine that older fridges/caravans will not all have the sophisticated electronics of the newer ones. In our case I always turn off the gas when towing and set the fridge to automatic. Whilst the fridge will prefer electricity over gas if available turning the gas supply off is good practice anyway for obvious reasons whilst towing. As soon as the electrical supply is turned off the fridge beeps and as soon as the car engine is started it stops beeping and works on 12v. The fridge is invariably cold upon arrival at a site!

Am I the only person who has never questioned the operation of my fridge whilst towing?

As for stop/start technology then as previously mentioned whilst towing this should be turned off if the car does not automatically turn it off. The reason, I believe, is to allow the turbo and cooling fans and any other cooling oil circulation to continue when stopped since towing will have placed a greater stress on the engine and probably increased temperatures.
Many people question why their fridge does not work properly on 12v so it seems that some professional fitters are not doing their job correctly. As you say it is very difficult to turn on your fridge 12 hours befroe departure if your caravan is kept in storage. Interesting post thanks.
 
Mar 4, 2019
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I have to take exception to the part which says it is contrary to manufacturers advice that the fridge will not cool on 12v when being towed.
I have no idea where this nugget of misinformation has come from but I can assure you that it is certainly NOT Dometic, and never has been, neither has it ever been said by Thetford.

The main reasons why it appears that the 12v does not cool the fridge are either not suitable wiring allowing enough power to be drawn, and not a long enough period of time with the engine running to allow the fridge to cool.

All three power sources are quite capable of operating the fridge at its optimum .
There is a third reason - the system voltage is too low because smart charging allows and maintains the battery voltage low. This is my personal experience with Ford and Peugeot. From my recent post in Peugeot forum:
"I followed the suggestion from someone in this forum and got a USB voltage reader. I start by saying that the voltage in cab is 0.1V lower than battery because of the drop as I am powering Garmin from the same outlet.
When using anything but light throttle, the voltage is 12.1 to 12.2, depending on state of battery.
After a few seconds of trailing throttle the voltage is 14.4-14.8.
So the alternator is controlled for low output when fuel is demanded, and only delivers a reasonable charge when fuel is nearly cut off. (However, if you load up electrically, all lights, wipers, fan on high, seat heaters, the voltage holds at low 12 so it does take up load)
What do I conclude from this?
1. You can easily arrive at the end of a long trip with lower battery charge than when you started (if you rarely trail throttle on the trip). An auto electrician tried to explain this to me a few years ago in relation to my Australian Ford, which has similar Smart Charging, but I didn't understand him. I was brought up believing a long trip charges your battery.
2. Peugeot fuel saving is costing us battery life. You need more than ever to regularly use a CTEK or similar clever charger to get reasonable battery life. Peugeot are happy to replace batteries early. They jumped in to replace mine 5 weeks after the car had left the assembly line, when I complained the SS wasn't working. It didn't fix it, but now I understand more about SS pre-conditions.
3. Could some reprogramming be done so the alternator delivers more charge with throttle open. I probably don't want to even look into this in case it introduces other problems, easier to use the CTEK.
3. I got onto this investigation because I was considering running high amperage cable to my Peugeot tow hitch to run caravan fridge and charge caravan leisure batteries while driving. WILL NOT WORK. Because I mainly travel flat freeways when caravanning, I am always on the throttle when towing (caravan air resistance). Voltage <12.2 minus cable losses will not run the fridge and will not charge the leisure batteries at all.
4. I was considering upgrading the 7 pin plug and wiring supplied by Peugeot dealer with towbar to 13 pin. WASTE OF MONEY as I will not get any more function from the 13 pin (except maybe reverse light on van).
5. Luckily in Slovakia I can pull the van with the fridge on gas because I have gas Mono Control. These are not legal in Australia so I can't effectively power my fridge while towing there with my 'Smart Charge' Ford.
6. I have picked up another tow vehicle, 2009 diesel Kia Sorento. It's voltage gets up to mid 14s a few km after starting, and stays there. It actually increases at higher revs like the good old days. It will run fridge and charge leisure batteries, and I'll bet my vehicle battery lasts longer.
 
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JTQ

May 7, 2005
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3. I got onto this investigation because I was considering running high amperage cable to my Peugeot tow hitch to run caravan fridge and charge caravan leisure batteries while driving. WILL NOT WORK. Because I mainly travel flat freeways when caravanning, I am always on the throttle when towing (caravan air resistance). Voltage <12.2 minus cable losses will not run the fridge and will not charge the leisure batteries at all.

An interesting contribution, thanks, but I do question if the statement that connecting heavy duty cable feed for the fridge, to the battery, "will not work".

That quizzing is solely based on an assumption that "smart" charging is surely smart enough not to endlessly leave a battery uncharged, if not over running?
The designer "must" I am assuming, have thought that some provision is needed to ensure the battery is fit to start the vehicle again after a long haul, retarting even if at way below zero C?
That being the case the battery would need to be "typically" held at no less than 80% state of charge. Therefore, even a wet battery will be at a minimum of 12.5 volts, and probably more as the fridge load will instigate an elevated voltage to effect a recharge.
With some goodly sized wiring directly from the battery to the fridge, then it will see most part of the battery's voltage.

Or am I crediting the designers of these charging systems with too much?
 
Nov 11, 2009
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There is a third reason - the system voltage is too low because smart charging allows and maintains the battery voltage low. This is my personal experience with Ford and Peugeot. From my recent post in Peugeot forum:
"I followed the suggestion from someone in this forum and got a USB voltage reader. I start by saying that the voltage in cab is 0.1V lower than battery because of the drop as I am powering Garmin from the same outlet.
When using anything but light throttle, the voltage is 12.1 to 12.2, depending on state of battery.
After a few seconds of trailing throttle the voltage is 14.4-14.8.
So the alternator is controlled for low output when fuel is demanded, and only delivers a reasonable charge when fuel is nearly cut off. (However, if you load up electrically, all lights, wipers, fan on high, seat heaters, the voltage holds at low 12 so it does take up load)
What do I conclude from this?
1. You can easily arrive at the end of a long trip with lower battery charge than when you started (if you rarely trail throttle on the trip). An auto electrician tried to explain this to me a few years ago in relation to my Australian Ford, which has similar Smart Charging, but I didn't understand him. I was brought up believing a long trip charges your battery.
2. Peugeot fuel saving is costing us battery life. You need more than ever to regularly use a CTEK or similar clever charger to get reasonable battery life. Peugeot are happy to replace batteries early. They jumped in to replace mine 5 weeks after the car had left the assembly line, when I complained the SS wasn't working. It didn't fix it, but now I understand more about SS pre-conditions.
3. Could some reprogramming be done so the alternator delivers more charge with throttle open. I probably don't want to even look into this in case it introduces other problems, easier to use the CTEK.
3. I got onto this investigation because I was considering running high amperage cable to my Peugeot tow hitch to run caravan fridge and charge caravan leisure batteries while driving. WILL NOT WORK. Because I mainly travel flat freeways when caravanning, I am always on the throttle when towing (caravan air resistance). Voltage <12.2 minus cable losses will not run the fridge and will not charge the leisure batteries at all.
4. I was considering upgrading the 7 pin plug and wiring supplied by Peugeot dealer with towbar to 13 pin. WASTE OF MONEY as I will not get any more function from the 13 pin (except maybe reverse light on van).
5. Luckily in Slovakia I can pull the van with the fridge on gas because I have gas Mono Control. These are not legal in Australia so I can't effectively power my fridge while towing there with my 'Smart Charge' Ford.
6. I have picked up another tow vehicle, 2009 diesel Kia Sorento. It's voltage gets up to mid 14s a few km after starting, and stays there. It actually increases at higher revs like the good old days. It will run fridge and charge leisure batteries, and I'll bet my vehicle battery lasts longer.

Thanks for the contribution. It may explain why the President of the Volvo Owners Club arrived in London in his new XC70 after a drive from Cornwall. When he came to restart his car next day it wouldn’t have it. The recovery technician explained a similar thing to him, and also said that stop- start should be used in city traffic to maintain battery life and performance. That was around 8 years ago.
 
Jun 20, 2005
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Upon changing the car I upgraded the caravan to the 13 pin system. The battery charging and fridge power cables are 2.5mm as opposed to the 12s 1.5mm. The fridge manufacturers clearly specify the cables required. The 13pin system is type approved to a set standard. I find it hard to believe any tow bar fitter today would not understand the complexities involved.I have stop start. 99.99% of my towing journeys do not result in stops of any magnitude. Never had a problem with the fridge not staying cool. My own Dometic is 175 watt on both 230 and 12 v.
 
Nov 16, 2015
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When I Had my New Santa Fe, I requested a 13 pin electrics to be fitted. When I connected the caravan, the battery charging, Fridge and ATC would not work. There was no earth return for them. Which should go directly to the cars Chassis and not to the earth return for trailer lights.
 
Mar 17, 2020
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When I Had my New Santa Fe, I requested a 13 pin electrics to be fitted. When I connected the caravan, the battery charging, Fridge and ATC would not work. There was no earth return for them. Which should go directly to the cars Chassis and not to the earth return for trailer lights.

It seems that my assumption that a professional tow-bar fitter would ensure all wiring was adequate and correctly installed was not entirely accurate Hutch. You obviously found an exception. Guess that's going to happen in most things on occasion and we can only speak from our own experiences. (Like you, I try not to worry too much about hearsay or urban legends that can emerge on forums at times).

Although I don't live in Barnsley I have bought my last three cars from a Barnsley garage (they have consistently given me the best deal). All three cars have been Santa Fe with my latest a 2020 Sante Fe Premium SE which I'm delighted with. The garage always uses Barnsley Tow-bar Centre for all things related to towing.

I have to say that all three cars have worked perfectly and, on the occasion I visited the Centre to purchase an accessory, I was mightily impressed with everything I saw.

I'm not an auto electrician nor a mechanic - just an ordinary caravan owner. I don't spend my time with a multi-meter in my hand and mainly use a torque wrench when checking wheel nuts. Yes, I'm "handy" and like many of my generation spent a lifetime taking care of jobs from roofing repairs to electrical re-wiring (when that was legal), plumbing etc etc.

My cars all were serviced on my drive as a young man. I even took a spare set of brake shoes to Europe one year as I expected to need them during the trip (This is true - honestly). I changed them in a lay-by in Switzerland when the scraping sound gave me no choice!

But, that aside, sometimes knowing relatively little about certain things is a benefit.

For example I've never expected my caravan fridge not to cool. I've presumed they are designed to do just that and since there is provision for a charge directly from my car whilst towing I've presumed that too is part of the "deal".

So far I've not been disappointed and the point I was trying to make in my initial post was that I am presuming my experience matches that of the vast majority.

Perhaps it's to be expected that on a forum such as this we frequently read of caravan failures/faults and rarely hear of quality experiences. (I have to say my own experiences with a new 2019 van have been, shall we say, unexpected!)

In a nutshell my simplistic view is that caravans have had fridges since the world began. Surely in all that time fridges have worked as intended and tow-bar fitters have adapted to any changes when necessary.

My assumption is that I'm one of 99.9% of caravan owners who have not had any problems with fridge operation nor car wiring. Fingers crossed things stay that way.

(OK, OK Maybe 95%)
 

JTQ

May 7, 2005
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My assumption is that I'm one of 99.9% of caravan owners who have not had any problems with fridge operation nor car wiring. Fingers crossed things stay that way.

(OK, OK Maybe 95%)

I suspect John that better reflects the number who don't realise there could be an issue, as for them problems don't spin out of lack of performance or even operation of caravan fridges and battery recharging on route?
 
Sep 26, 2018
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I would also imagine that everyone turns their fridge on (if possible of course) at least 12 hours prior to beginning a journey. If they don't then I respectfully suggest they should.
We've never had a problem with any fridge and that includes overnight ferry travel as well as towing in the upper 30ies in Europe.

That's all very well if your caravan is at home, some of us keep ours in storage with no mains hook up!
 
Mar 14, 2005
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It seems that my assumption that a professional tow-bar fitter would ensure all wiring was adequate and correctly installed was not entirely accurate ......

A "professional" towbar fitter would indeed fit what the customer has ordered and make sure it's correctly fitted to contract.

But the problem is some customers may not realise that the supplementary services are not always included in the electrical kits, and they need to be specifically ordered.

A good towbar fitter aught to ask the customer what they intend to tow, and establish if the supplementary should be added to the order.

Equally a good towbar fitter should be aware of tow vehicles that have issues with providing adequate supplementary supplies, and advise customers accordingly.

Sadly sometimes genuine mistakes can occur where something goes wrong, but the professional will put their mistake right, but customers must accept their responsibility for ordering the wrong things. And of course there can be the odd rouge trader who tries to avoid their responsibilities.

Neither the fridge or caravan manufacturers can know what vehicles will be used by customers, so they are not in a position to prevent tow vehicle based problems with the exception of ensuring suitable gauges of conductor are used in their products.

However it should becoming clearer to all, that as car manufacturers strive to make their products more efficient, they are using power saving processes, like smart alternators and stop start running. With such developments it can no longer be assumed that adequate supplementary supplies will be available. Fridge manufacturers are unlikely to be able to magically make their products work when no power is available, but they might strive to improve insulation so the fridges have lower ambient heat transfer.

The car makers should also be asked to look at ways to make supplementary power available when towing. Most in car systems are now controlled by programmable ECU's and perhaps a towing setting could be implemented that ensures supplementary power is maintained. In many cases there are sufficient sensors already fitted to cars that could automatically detect when a trailer is hitched, or of course it could be a user operated switch.
 
Jun 16, 2010
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Professional fitter wired the fridge circuit to the boot accessory socket in one of the cars i had, unsurprisingly it didn't fare too well.

So on paper seemed okay (multimeter showed 12V at the pin), in practice the socket just cut off.

Had to run a separate feed from the battery via a relay to deal with that.
 
Mar 4, 2019
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A "professional" towbar fitter would indeed fit what the customer has ordered and make sure it's correctly fitted to contract.

But the problem is some customers may not realise that the supplementary services are not always included in the electrical kits, and they need to be specifically ordered.

A good towbar fitter aught to ask the customer what they intend to tow, and establish if the supplementary should be added to the order.

Equally a good towbar fitter should be aware of tow vehicles that have issues with providing adequate supplementary supplies, and advise customers accordingly.

Sadly sometimes genuine mistakes can occur where something goes wrong, but the professional will put their mistake right, but customers must accept their responsibility for ordering the wrong things. And of course there can be the odd rouge trader who tries to avoid their responsibilities.

Neither the fridge or caravan manufacturers can know what vehicles will be used by customers, so they are not in a position to prevent tow vehicle based problems with the exception of ensuring suitable gauges of conductor are used in their products.

However it should becoming clearer to all, that as car manufacturers strive to make their products more efficient, they are using power saving processes, like smart alternators and stop start running. With such developments it can no longer be assumed that adequate supplementary supplies will be available. Fridge manufacturers are unlikely to be able to magically make their products work when no power is available, but they might strive to improve insulation so the fridges have lower ambient heat transfer.

The car makers should also be asked to look at ways to make supplementary power available when towing. Most in car systems are now controlled by programmable ECU's and perhaps a towing setting could be implemented that ensures supplementary power is maintained. In many cases there are sufficient sensors already fitted to cars that could automatically detect when a trailer is hitched, or of course it could be a user operated switch.
“The car makers should also be asked to look at ways to make supplementary power available when towing.” Well said Prof JohnL. My car already senses the trailer is connected and makes changes; turns off rear bumper sensors, trailer indication on dash and probably does something with stability control and more. A change to BSI computer program as you suggest would be good.
 
Mar 14, 2005
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Professional fitter wired the fridge circuit to the boot accessory socket in one of the cars i had, unsurprisingly it didn't fare too well.

So on paper seemed okay (multimeter showed 12V at the pin), in practice the socket just cut off.

Had to run a separate feed from the battery via a relay to deal with that.
They weren't that professional then were they!
 
Jun 20, 2005
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Today’s tow bar fitter is 20% mechanical fitting, 80% plugging his laptop into the car’s computer rejigging everything. My chap spent 30 minutes showing me on his PC how he had made changes to the VW ecu to handle with and without a caravan attached. It’s not pot luck. I can say VW have allowed for the tow bar fitter intervention. I am sure most others have done the same.
 
Nov 16, 2015
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The fitters and Engineers can only do what their training gives them. After that experience gives the rest.
 
Jul 18, 2017
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Today’s tow bar fitter is 20% mechanical fitting, 80% plugging his laptop into the car’s computer rejigging everything. My chap spent 30 minutes showing me on his PC how he had made changes to the VW ecu to handle with and without a caravan attached. It’s not pot luck. I can say VW have allowed for the tow bar fitter intervention. I am sure most others have done the same.
Same thing with modern cars. If the computer does not tell them what they need to do, they are lost. In many cases the computer cannot detect the fault correctly or what caused the fault which is why repairs can be expensive!
 

JTQ

May 7, 2005
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In many cases the computer cannot detect the fault correctly or what caused the fault which is why repairs can be expensive!

Conversely, I rather suspect there are many cases where given no computer aided diagnostics, that a lot of operatives would also struggle to know what has gone wrong, making again for an expensive repair. eg. let's change this bit in hope it cures it!
 
Jun 20, 2005
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Conversely, I rather suspect there are many cases where given no computer aided diagnostics, that a lot of operatives would also struggle to know what has gone wrong, making again for an expensive repair. eg. let's change this bit in hope it cures it!
Like the old points and condenser. Remember carrying them as spares👍👍
 
Nov 11, 2009
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Like the old points and condenser. Remember carrying them as spares👍👍
My father only used his early cars at weekends and very often in winter the distributor cap , leads and plugs had to be removed from the car taken home some couple of miles away and warmed in the oven. Thank heavens when I bought my first car, a mini, WD 40 had been invented.
 
Nov 6, 2005
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My father only used his early cars at weekends and very often in winter the distributor cap , leads and plugs had to be removed from the car taken home some couple of miles away and warmed in the oven. Thank heavens when I bought my first car, a mini, WD 40 had been invented.
As a cost-cutting exercise, many cars of that era had plug leads made with carbon-impregnated string cores - these quickly broke down in service - a good tip at the time was to replace with "high Performance" copper-cored type.
 

JTQ

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As a cost-cutting exercise, many cars of that era had plug leads made with carbon-impregnated string cores - these quickly broke down in service - a good tip at the time was to replace with "high Performance" copper-cored type.

I seem to remember the use of compressed carbon was all about RF interference mitigation rather than "a cost cutting exercise".

In fact, changing them out to a basic copper core was the cheapest option. They then needed to change to suppressor plug caps.

Though I found the carbon ones did have a finite lifetime, developing core cracks that then arced leaving witness burn marks in the outer sheath.
 
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Nov 11, 2009
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As a cost-cutting exercise, many cars of that era had plug leads made with carbon-impregnated string cores - these quickly broke down in service - a good tip at the time was to replace with "high Performance" copper-cored type.

Yes copper may have been better although his 1938 Ford 10 would still have found it hard to get over 50 mph on the M1 even downhill with a tail wind. But at least he would have saved the task of heating the leads so frequently. 👍
 

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