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Nov 11, 2009
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Why not a plug in electric cool box in the boot, then irrespective of what the alternator does the OP will at least have some cold beers and cool food.
 
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Jan 3, 2012
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We have a small 15L cool bag and it fits between the winch and my mobility scooter I just plug it into the boot 12v so far no problems
 

Sam Vimes

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Sep 7, 2020
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Aircon uses an engine driven compressor, so no additional electrical load, so unlikely to work.
While its generally true that an ICE will drive the aircon compressor, this may still have an affect on the Smart Altenator system. On my car when the Smart Alternator is in low votage output mode, turning on the Aircon makes no difference to the voltage level - its stays low.

However, on some implemenations people have found this to work. Most likely because the Battery Management System detects an extra load on the engine and turns up the Smart Alternator output. Some Smart Alternators typically drop into low output mode when the engine load is light - e.g coasting or breaking. Which is what mine does. But on some systems when extra load is detected the output voltage goes up.
 
Nov 30, 2022
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While its generally true that an ICE will drive the aircon compressor, this may still have an affect on the Smart Altenator system. On my car when the Smart Alternator is in low votage output mode, turning on the Aircon makes no difference to the voltage level - its stays low.

However, on some implemenations people have found this to work. Most likely because the Battery Management System detects an extra load on the engine and turns up the Smart Alternator output. Some Smart Alternators typically drop into low output mode when the engine load is light - e.g coasting or breaking. Which is what mine does. But on some systems when extra load is detected the output voltage goes up.
I just load my fridge with cold stuff! Never bother switching to 12v, never had a problem, even when taking the ferry to Spain so I do seriously wonder why some folk spend all that money to address a problem that basically doesn't exist.
Each to his own of course.
 
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Sam Vimes

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The problem does exist and people have to find ways around the short comings of a caravan industry that is so behind the times.

Caravans and their fridges are sold on the basis that they can be kept cool by having the tow car power then fridge. Equally they're sold on the basis that the leisure battery can be charged whilst being towed.

Yet sufficient numbers of people have problems with fridges and some have problems with battery charging. In fact battery discharging.

The caravan industry points the finger towards the towbar fitters. They in turn point the digit to the car manufacturers.

Smart Alternators have been around for a long while and so has the problem. The caravan industry could step up and fit as standard DC-DC converters to fix the problem but they won't. It's down to the owner.

Just as it is to fit your own leisure battery and gas bottle.

Caravan electrics and controls are still in the dark ages, again, IMO.
 
Jul 18, 2017
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I just load my fridge with cold stuff! Never bother switching to 12v, never had a problem, even when taking the ferry to Spain so I do seriously wonder why some folk spend all that money to address a problem that basically doesn't exist.
Each to his own of course.
We stop overnight in Portsmouth and switch fridge onto coldest settings. We arrive in Spain the next day and drive to Zaragoza and arrive at about 8pm. All the stuff in the freezer is still frozen. No issue.
 
Nov 30, 2022
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We stop overnight in Portsmouth and switch fridge onto coldest settings. We arrive in Spain the next day and drive to Zaragoza and arrive at about 8pm. All the stuff in the freezer is still frozen. No issue.
Which is the point I have been making! :rolleyes:

Caravan fridges don't need to be powered whilst being towed, yours, and my, first hand experience proves that, yet still others dismiss our views as being totally wrong and utterly misinformed because they differ from their opinions, those opinions are not formed out of practical experience (such as ours) but by incorrect perceptions (which will doubtless continue)
 
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Jun 20, 2005
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Some Smart Alternators typically drop into low output mode when the engine load is light - e.g coasting or breaking. Which is what mine does. But on some systems when extra load is detected the output voltage goes up.
I had a chat with some other caravanners about this.

What truly is a smart alternator?
A rhetorical question but dependant on engine speed ? I don’t think is necessarily true.

More likely the voltage draw which isn’t actually connected to engine speed.
My 13 pin wiring has three out puts of relevance here.
1. Charge caravan battery
2. Live feed to ATC.
3. Feed to 12 v fridge.

Never in the last 20 years with three modern cars have I had a problem?
What is the true issue with a smart alternator? It can’t be that smart if it doesn’t recognise points 1,2 &3.

I have suspected for many years that perhaps I should remove the fridge vent covers before departure rather than on arrival🤔🤔
 
Nov 11, 2009
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I had a chat with some other caravanners about this.

What truly is a smart alternator?
A rhetorical question but dependant on engine speed ? I don’t think is necessarily true.

More likely the voltage draw which isn’t actually connected to engine speed.
My 13 pin wiring has three out puts of relevance here.
1. Charge caravan battery
2. Live feed to ATC.
3. Feed to 12 v fridge.

Never in the last 20 years with three modern cars have I had a problem?
What is the true issue with a smart alternator? It can’t be that smart if it doesn’t recognise points 1,2 &3.

I have suspected for many years that perhaps I should remove the fridge vent covers before departure rather than on arrival🤔🤔
Are you talking wrtcthe vent covers that are required for cold weather operation?
 
Nov 16, 2015
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My Santa Fe manages to charge the caravan battery and keep the fridge cool whilst the car is running, none of this modern technology or smart alternators.

BUT, electronic had brake stuck on yesterday and I had to get Green flag out to get me home. 1/2 hour before they arrived I managed to release it.
Local Hyundai dealer can't get me in until 30th July.
Recall on handbrake fuse. As well.
 
Jun 20, 2005
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Are you talking wrtcthe vent covers that are required for cold weather operation?
Yes those vents. As you know Dometic et al say the vents must be removed when the ambient temperature is above 8 degs c. Not very hot😉
I freely admit I travel at vastly greater temperatures with the vents in place. Am I wrong? Probably🙉
This thread is making me think we all need to reassess the situation 🤔
 
Nov 6, 2005
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My Santa Fe manages to charge the caravan battery and keep the fridge cool whilst the car is running, none of this modern technology or smart alternators.

BUT, electronic had brake stuck on yesterday and I had to get Green flag out to get me home. 1/2 hour before they arrived I managed to release it.
Local Hyundai dealer can't get me in until 30th July.
Recall on handbrake fuse. As well.
Hyundai Santa Fe has had a smart alternator certainly since 2010, possibly since 2006.

In essence a smart alternator has electronic control which determines when it charges and when it just idles - in basic form the alternator charges when the throttle is released and the engine is on the over-run and stops charging during periods of full throttle - but in addition to that the electronics manages the battery state of charge and charges or not according to demand.
 
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Nov 6, 2005
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Yes those vents. As you know Dometic et al say the vents must be removed when the ambient temperature is above 8 degs c. Not very hot😉
I freely admit I travel at vastly greater temperatures with the vents in place. Am I wrong? Probably🙉
This thread is making me think we all need to reassess the situation 🤔
Are you referring to removing the Vent winter covers or removing the vents themselbves.
 
Nov 11, 2009
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Yes those vents. As you know Dometic et al say the vents must be removed when the ambient temperature is above 8 degs c. Not very hot😉
I freely admit I travel at vastly greater temperatures with the vents in place. Am I wrong? Probably🙉
This thread is making me think we all need to reassess the situation 🤔
Once cooler weather had passed I would remove the vent covers and they wouldn’t be used again until later autumn.
 
Jun 20, 2005
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Once cooler weather had passed I would remove the vent covers and they wouldn’t be used again until later autumn.
Admittedly many decades ago Chipping Sodbury caravans said keep them fitted whilst travelling to avoid” foreign bodies” stones etc entering and damaging the fridge parts.
 
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Nov 11, 2009
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Admittedly many decades ago Chipping Sodbury caravans said keep them fitted whilst travelling to avoid” foreign bodies” stones etc entering and damaging the fridge parts.
Subjectively I’d think nit having them fitted whilst travelling would help the fridges cooling, assuming that is that the alternator pokes out sufficient to have the fridge working. Must say I never had issues with the fridges in UK, although when going to southern france I did fit a vent fan. I also mirrored the approach followed by Hutch and Plodd.
 
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Jul 15, 2008
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.....I too have a Santa Fe 2016.
It is fitted with a battery voltage display that always shows 14.2 volts when towing.
I have measured the voltage at the caravan battery and the supply at the back of the refrigerator ...both 13.8 volts.
The leisure battery charging and the refrigerator work just fine.
They have to, as every year I have been doing a 4 day tow from Dieppe to Andalusia and the same on the return.
I fit covers across the vents when towing.......absorption refrigerators need suficient heat to work efficiently.
Airflow of up to 60 mph over unrestricted vents gives much reduced cooling.

Works for me....but each to their own.
 
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Sep 4, 2011
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When I had my Santa Fe it had Main Dealer fitted towbar, previous motors I had always fitted own towbars over a period of 40 years, I found that fridge would not work on towing. I measured voltage a back of fridge and when alternator charging at 14,2 volts the fridge was only 12.9 volts. Not enough for the fridges circuit board relay to operate the Element, I then ran a heavier cable through the motor and this cured the voltage drop giving 13.8 v at fridge and never ever then had a problem until I sold the car. The Sorento I had before that I had used a heavier cable when wiring it and that worked from day one. If there is enough demand from the Battery ie Headlights or fridge Element the Smart Alternator will be charging permanently at 14.2 volts and the fridge will run ,as long as there is not voltage drop due to undersized wiring,
 
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Jun 20, 2005
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Interesting different views on the vent covers.

Reading Bill’s post I can now appreciate the advice from Chipping Sodbury Caravans.

My fridge has always remained well chilled on 12 v whilst towing. Whilst I assumed I was protecting the fridge components from damage but in fact I have been doing a Bill avoiding overcooling whilst towing!👍
 

Sam Vimes

Moderator
Sep 7, 2020
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I had a chat with some other caravanners about this.

What truly is a smart alternator?
A rhetorical question but dependant on engine speed ? I don’t think is necessarily true.

More likely the voltage draw which isn’t actually connected to engine speed.
My 13 pin wiring has three out puts of relevance here.
1. Charge caravan battery
2. Live feed to ATC.
3. Feed to 12 v fridge.

Never in the last 20 years with three modern cars have I had a problem?
What is the true issue with a smart alternator? It can’t be that smart if it doesn’t recognise points 1,2 &3.

I have suspected for many years that perhaps I should remove the fridge vent covers before departure rather than on arrival🤔🤔
Smart Alternators came about to improve mpg and to reduce emissions. They do so by reducing the load on the engine at certain times and allow the battery to power the onboard electrics/electronics. Then, when the battery is discharged to a certain level the Smart Alternator kicks in to recharge it. This can be done most efficiently when the vehicle is coasting or breaking - as in regenerative breaking.

One of the issues is that the specification for vehicle electrics, specifically at the tow bar connector isn't that precise. Nor is the caravan electrics. All are typically quoted as being 12V systems but this is not the case. Car voltages vary considerably now that Smart Alternators are widely used. Caravan wiring is poor and considerable voltage drops can occur, especially on high loads like that needed by a fridge or battery charging.

So when the Smart Alternator does its 'smart thing' the voltage at the tow connector isn't enough to power the caravan's needs.

Car manufacturers and indeed tow bar wiring manufacturers don't specifically know whats going to be connected up. It may well be the lowest common towing situation is considered and that's a 'dumb trailer' that just needs power for lights.

Caravans introduce a new requirement as you stated but this is where the three levels - car/wiring harness/caravan all put the onus on each of the other to address the problem.

Car manufacturers could say ' We need to have improved mpg and reduced emissions even when towing, so we'll keep the Smart Alternator functioning.

Tow bar wiring manufacturers could say - we just interface the two.

Caravan manufacturers just close their eyes to the problem.
 

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