Now we've beaten that one to death lets hope Sam Vimes gets the problem sorted out, as it does appear to be vehicle related and not the fridge itself.
I was under the impression that many canal boats and river cruisers operated on a 240v system when moving as they are able to generate the 240v constantly?
When moored they connected to 240v. I guess that the 12v system on them would be in addition to the 240v and serve the same function as the 12v system on a caravan.
Maybe someone with such a boat can confirm?
My fridge wiring is now a bit non standard in that it also allows 12v running from the vans lithium batteries, the “ferry setting”. You do need a lot of storage to do this though. A useful addition at the time I did this was a blue LED fitted into the trim above the fridge that is wired to the 12v feed. Now it’s simple to spot if that feed is on, important if you have a battery feed available. It’s a great cross check that the cars towbar system is working properly too, when coupled it lights when the engine is running as it should. The cars electrics are as smart as they could be in a modern Audi, yet it’s perfectly possible to have the required 2x 12v feeds to the caravan. The dedicated module for the towbar should sort all this regardless of alternator peculiarities as I’m sure you are aware. It’s canbus controlled from the cars management system as far as I’m aware. Certainly havoc was wreaked on our car when Audi recently chose to reprogram the car without realising the towbar box was in place, until that was sorted with reprogramming it behaved like the car had major faults so the towbar setup is heavily integrated into the vehicles systems for sure. I think some of the smart alternator myths came about because some people have tried just jumping towbar electrics onto a modern cars wiring in the old style, that ain’t gonna work,
Steve
You know I spent a lot of time getting my fridge to work off the car properly after all if the facility is there it has to work. Things that don’t work but should drive me to distraction. Having said that we never use the fridge when travelling. I just don’t trust all that weight of food and bottles bouncing around in a fragile plastic box. We take a large cool box for our fridge stuff and stock the fridge up on arrival. A couple of large freezer blocks keep things cold and frosty until the fridge takes over.
When wiring was fitted to our current Jeep it was never connected so that the fridge could be used. As we hardly ever bothered with using the facility previously I never bothered with updating it. Our cool bags work just as well.
Apologies for the late follow up on my fridge issue. Got home a couple of days back to find the jungle that passes for our garden had got even wilder. This is bit of a long read and only Part 1, so read or ignore – your choice.
So, it seems that the issue of fridges, charging and possibly ATC power when towing with a car with a smart alternator has been around for quite a while. This occurs across a wide range of towing vehicles and caravans. Some report no problems while other have the issue with the same car/caravan. There are many anecdotes about how to work around this issue such as turning on headlights, aircon, disabling Stop/Start control and revving the engine. I’m a bit sceptical about how affective these are and suspect that they may only be a short term work around. After all how many people will know what’s happening to the fridge in the caravan while driving. We only found a problem when the Magnums were a bit runny when we arrived. When I noticed our fridge not working, none of the proposed work arounds made any difference.
I suspect that implementation of the ‘smarts’ for the alternator vary from car to car as does the towbar electrics and the caravan wiring and equipment which could account for why there are different experiences.
I’ve been giving some thought to the potential causes of the problem, which I believe are not really due to the inclusion of a smart alternator but are more to do with the implementation of the elements in connecting the car to the fridge etc. The smart alternator function just causes the fault to cause the failure to manifest itself.
I need to do some more actual measurements to check my theory out but my conjecture is that the problem lies with the voltage drop from the towbar connector to the fridge (I can’t tell yet if this is also affecting charging the leisure battery). Having reached this conclusion, it was satisfying to stumble across a Youtube video from Sterling Power (link below) that concurred with my reasoning. However, I think that while Sterling Power have a good solution – that costs a lot of money – they have missed one crucial point. That is the caravan manufacturers state that the fridge should work and the battery can be charged when towing from a car with a 12V source. It would appear that if the source was indeed at 12V this wouldn’t work in some systems due to the voltage drop along the wiring etc.
My particular fridge – Dometic RMS8551 – requires about 10A on the switched 12V. Measuring just my wiring from towbar connector to fridge, there’s about 5m of 2.5mm2 cable. Taking some average value for the resistance of this cable its possible to get a 1.5V drop in voltage at the fridge and that’s not taking into account drops across connectors and fuses. It so happens that the fridge has an undervoltage detection circuit which kicks in at 10.5V. So even if my car was giving out 12V the fridge wouldn’t work.
My next step when the season has finished is to try and do some actual measurements before I query the caravan manufacturers.
View: https://www.youtube.com/watch?v=JsMuXScOBWw
So, it seems that the issue of fridges, charging and possibly ATC power when towing with a car with a smart alternator has been around for quite a while. This occurs across a wide range of towing vehicles and caravans. Some report no problems while other have the issue with the same car/caravan. There are many anecdotes about how to work around this issue such as turning on headlights, aircon, disabling Stop/Start control and revving the engine. I’m a bit sceptical about how affective these are and suspect that they may only be a short term work around. After all how many people will know what’s happening to the fridge in the caravan while driving. We only found a problem when the Magnums were a bit runny when we arrived. When I noticed our fridge not working, none of the proposed work arounds made any difference.
I suspect that implementation of the ‘smarts’ for the alternator vary from car to car as does the towbar electrics and the caravan wiring and equipment which could account for why there are different experiences.
I’ve been giving some thought to the potential causes of the problem, which I believe are not really due to the inclusion of a smart alternator but are more to do with the implementation of the elements in connecting the car to the fridge etc. The smart alternator function just causes the fault to cause the failure to manifest itself.
I need to do some more actual measurements to check my theory out but my conjecture is that the problem lies with the voltage drop from the towbar connector to the fridge (I can’t tell yet if this is also affecting charging the leisure battery). Having reached this conclusion, it was satisfying to stumble across a Youtube video from Sterling Power (link below) that concurred with my reasoning. However, I think that while Sterling Power have a good solution – that costs a lot of money – they have missed one crucial point. That is the caravan manufacturers state that the fridge should work and the battery can be charged when towing from a car with a 12V source. It would appear that if the source was indeed at 12V this wouldn’t work in some systems due to the voltage drop along the wiring etc.
My particular fridge – Dometic RMS8551 – requires about 10A on the switched 12V. Measuring just my wiring from towbar connector to fridge, there’s about 5m of 2.5mm2 cable. Taking some average value for the resistance of this cable its possible to get a 1.5V drop in voltage at the fridge and that’s not taking into account drops across connectors and fuses. It so happens that the fridge has an undervoltage detection circuit which kicks in at 10.5V. So even if my car was giving out 12V the fridge wouldn’t work.
My next step when the season has finished is to try and do some actual measurements before I query the caravan manufacturers.
Excellent script Sam. 👏👏
I suspect when you start your measuring exercise you may be surprised. The average alternator should churn out a minimum of 13 v, usually somewhere between 13.5v and 14.5v. Say your is only 12v and applying your cable resistance theory you may get your Eureka moment😉🤪.
Roll,on the next instalment👍👍
I suspect when you start your measuring exercise you may be surprised. The average alternator should churn out a minimum of 13 v, usually somewhere between 13.5v and 14.5v. Say your is only 12v and applying your cable resistance theory you may get your Eureka moment😉🤪.
Roll,on the next instalment👍👍
We have the exact same fridge and the 12v only maintains the temperature. It does not lower the temeprature. Now we simply fill the freezer with frozen stuff and it seems to keep the fridge cool for at least 48 hours providing you are not opening and closing the door. On arrival in Spain on the overnight ferry the food was still frozen and this was when we got to Zaragoza. We have not bothered with having the relay fitted to have the fridge operational while driving.
Voltage drop certainly does exist, and at 12V (nominal) the voltage drop becomes a greater proportion of the desired voltage and can become more of problem.
The NCC recommendation for electrical cable size in caravans is only 1.5mm2 csa, so are you sure your cable size is 2.5mm2 csa?
The industry standard conductor resistance tables give
1.5mm2 csa Copper as 12.1 Ohms /Km (or 0.0121 per m)
2.5mm2 csa Oopper as 7.41 Ohms /Km (or 0.00741 per m)
Your 5m length should give you a resistance and 10A voltage drop of
5m of 1.5csa 0.0605 Ohms @10A = 0.60 V drop
5m of 2.5csa 0.0371 Ohms @10A = 0.37 V drop
However as the same current must also pass through the 0V return wire the same voltage drop will occur there also
Round trip voltage drop (10m)
1.5 csa 1.2V
2.5 csa 0.74V
If your measurements deviate significantly from these values, then you might have a high resistance connection somewhere. It could be a bad contact in the habitation relay.
All these are cable at 20C as temperature increases the resistances will rise but for normal caravans work the difference is small enough to be negligible.
The NCC recommendation for electrical cable size in caravans is only 1.5mm2 csa, so are you sure your cable size is 2.5mm2 csa?
The industry standard conductor resistance tables give
1.5mm2 csa Copper as 12.1 Ohms /Km (or 0.0121 per m)
2.5mm2 csa Oopper as 7.41 Ohms /Km (or 0.00741 per m)
Your 5m length should give you a resistance and 10A voltage drop of
5m of 1.5csa 0.0605 Ohms @10A = 0.60 V drop
5m of 2.5csa 0.0371 Ohms @10A = 0.37 V drop
However as the same current must also pass through the 0V return wire the same voltage drop will occur there also
Round trip voltage drop (10m)
1.5 csa 1.2V
2.5 csa 0.74V
If your measurements deviate significantly from these values, then you might have a high resistance connection somewhere. It could be a bad contact in the habitation relay.
All these are cable at 20C as temperature increases the resistances will rise but for normal caravans work the difference is small enough to be negligible.
Some additional points of interest.
1. My fridge can run exclusively on 12Vdc - not just to maintain a pre-cooled state but to get it to the desired temperature in the first instance. While this is possible its will impose a considerable drain on the battery. In order to prevent this, the installation in my caravan does not permit running it like this so its only when the car's engine is running will it cool on the 12v setting.
2. Habitation relay. I wonder if modern caravans have a Habitation Relay in the same way that older vans had. What makes me query this is that my Fridge appears to take the switched 12v (pin10) directly and will detect itself no volts or an undervoltage condition - so it only cools on 12V when the car engine is turning over. A 12V supply for the control electronics is either from the direct 12V (pin9) or from the leisure battery.
The Power Distribution Unit is a smart charger and 12V supply to the caravan. Maybe it includes a habitation relay of sorts but I can't work out if it also controls the switched 12V to the fridge. It must control switching of the direct 12V in order for the electronic controls on the fridge to work on the caravan or car supply.
3. Commercially available 12 core cable for caravans seems to include a mix of wires - 7 x 0.65mm2, 1 x 1.5mm2 and 4 x 2.5mm2.
The cable configuration is in the table below.
Resistance figures for copper cable seem to vary and I took what appeared to be a nominal value - I've seem higher and lower values. Either way a voltage drop is always going to occur but I need to determine what I'm seeing. I also need to monitor Pin10 at the towbar under load conditions and determine the lowest voltage that's possible.
Just some other points specific to my car - Qashqai 1.5dci.
1. From a cold start - left over night but after a long run the previous day - when backed up to the caravan and coupled up, the fridge powers on from the car. During this short running and connection period the smart alternator is probably at a high output to make up the drain on the battery from starting.
2. After a journey of about 30-40 minutes, when I stopped for coffee and cake, I checked the fridge before switching off the engine. It was not running. Presumably by this time and after this length of journey the smart alternator was at a low output. I tried switching on headlights, aircon, and disabling stop/start. This made no difference. However, its possible that the fridge controls need a little time to establish that the volts where back in spec. and maybe I didn't give it long enough.
3. After the stop with engine off, of about 20minutes, I restarted the car and checked the fridge - it was working. Probably due to the same affect as in point 1 above. The smart alternator is on high output as a result of a drain on the battery due to starting.
4. We drove home but the fridge was off again when we got there.
5. So it looks like the fridge is going to work intermittently depending on the state of the smart alternator. Provided the smart alternator output doesn't go below 12V then it should work continuously.
Something to consider - if you have a car with a battery that's getting old and can't maintain a decent charge, would the smart alternator running continuously at high output or at least for a longer duration than one with a good battery?
1. My fridge can run exclusively on 12Vdc - not just to maintain a pre-cooled state but to get it to the desired temperature in the first instance. While this is possible its will impose a considerable drain on the battery. In order to prevent this, the installation in my caravan does not permit running it like this so its only when the car's engine is running will it cool on the 12v setting.
2. Habitation relay. I wonder if modern caravans have a Habitation Relay in the same way that older vans had. What makes me query this is that my Fridge appears to take the switched 12v (pin10) directly and will detect itself no volts or an undervoltage condition - so it only cools on 12V when the car engine is turning over. A 12V supply for the control electronics is either from the direct 12V (pin9) or from the leisure battery.
The Power Distribution Unit is a smart charger and 12V supply to the caravan. Maybe it includes a habitation relay of sorts but I can't work out if it also controls the switched 12V to the fridge. It must control switching of the direct 12V in order for the electronic controls on the fridge to work on the caravan or car supply.
3. Commercially available 12 core cable for caravans seems to include a mix of wires - 7 x 0.65mm2, 1 x 1.5mm2 and 4 x 2.5mm2.
The cable configuration is in the table below.
Resistance figures for copper cable seem to vary and I took what appeared to be a nominal value - I've seem higher and lower values. Either way a voltage drop is always going to occur but I need to determine what I'm seeing. I also need to monitor Pin10 at the towbar under load conditions and determine the lowest voltage that's possible.
| Function | Colour | csa mm2 | |
| Pin 1 | L/H Direction indicator light | Yellow | 0.65 |
| Pin 2 | Rear fog light | Blue | 0.65 |
| Pin 3 | Return for contacts 1 < 2 & 4 < 8 | White | 1.5 |
| Pin 4 | R/H Direction indicator | Green | 0.65 |
| Pin 5 | R/H Rear position lights | Brown | 0.65 |
| Pin 6 | Stop lights | Red | 0.65 |
| Pin 7 | L/H Rear position lights | Black | 0.65 |
| Pin 8 | Reversing light | Pink | 0.65 |
| Pin 9 | Permanent power supply +12V | Orange | 2.5 |
| Pin 10 | Switched power supply | Grey | 2.5 |
| Pin 11 | Return for contact 10 | White/Black | 2.5 |
| Pin 12 | Not used | ||
| Pin 13 | Return for contact 9 | White/Red | 2.5 |
Just some other points specific to my car - Qashqai 1.5dci.
1. From a cold start - left over night but after a long run the previous day - when backed up to the caravan and coupled up, the fridge powers on from the car. During this short running and connection period the smart alternator is probably at a high output to make up the drain on the battery from starting.
2. After a journey of about 30-40 minutes, when I stopped for coffee and cake, I checked the fridge before switching off the engine. It was not running. Presumably by this time and after this length of journey the smart alternator was at a low output. I tried switching on headlights, aircon, and disabling stop/start. This made no difference. However, its possible that the fridge controls need a little time to establish that the volts where back in spec. and maybe I didn't give it long enough.
3. After the stop with engine off, of about 20minutes, I restarted the car and checked the fridge - it was working. Probably due to the same affect as in point 1 above. The smart alternator is on high output as a result of a drain on the battery due to starting.
4. We drove home but the fridge was off again when we got there.
5. So it looks like the fridge is going to work intermittently depending on the state of the smart alternator. Provided the smart alternator output doesn't go below 12V then it should work continuously.
Something to consider - if you have a car with a battery that's getting old and can't maintain a decent charge, would the smart alternator running continuously at high output or at least for a longer duration than one with a good battery?
It could do with a buffer. If, while traveling, the fridge took it’s power from the caravan battery, so long as the van was getting power from the car, the caravan battery would then only charge intermittently, as and when the smart alternator deems fit.
Sounds, simple (to me). But would need some complex logic circuits I would think.
Alternatively. Smooth the cooling effect out by using ice packs. 😏
Regarding voltage drop. In all my previous cars, not my present one, I did my own wiring. For both fridge and battery, I always fed an 8 or 10 mm cable through to the boot to minimise the drop. The 12 core cable only provides minimum cross section. But I have heard that some installers feed this through the car with even thinner wires. Thereby agrevating the problem.
John
John
Sounds, simple (to me). But would need some complex logic circuits I would think.
Alternatively. Smooth the cooling effect out by using ice packs. 😏
Regarding voltage drop. In all my previous cars, not my present one, I did my own wiring. For both fridge and battery, I always fed an 8 or 10 mm cable through to the boot to minimise the drop. The 12 core cable only provides minimum cross section. But I have heard that some installers feed this through the car with even thinner wires. Thereby agrevating the problem.
John
John
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Our old Dometic hit 2C after a good time on 12v car feed a couple of days ago. Also managed a -1C on gas. Ooops, too low. Setting needs watching once Autumn comes..
Steve
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So far I haven't gotten around to the real Part 2 investigation into the case of the non working fridge when towing. However, I have discovered that I have Part 2 of the problem.
Problem 1 is that due to the Smart Alternators dropping the voltage output when in an 'Eco' mode the fridge doesn't get enough volts to turn on.
Problem 2 is that the Leisure Battery is discharging when towing.
This is a problem reported elsewhere on the Internet and indeed has been mentioned on this forum a number of years back.
What happens is that the Leisure Battery gets connected via Pin 9 to the cars 12v system and effectively the car sees both batteries as one. The Smart Alternator is programmed to cut the output voltage and not charge the battery(s) until they drop supposedly to about 80% capacity at which point it will cut in and start charging.
To me dropping to 80% doesn't sound too much of a discharge but on a few occassions now we've arrived home or on site and found the motor mover wont work because the battery is 'flat' whereas its been on charge, either at home or on site for a number of hours or days.
I need to make a few measurements if I can but I've put this off until now because I didn't want to screw up anything before our last trip and the annual service, which is next week.
There are two potential solutions to both problems:-
1, Install a Battery to Battery Charger - essentially a DC to DC convertor that takes a wide input voltage range (from the car in this case) and produces a constant 13.8v out.
These cost from £150 upwards.
2. Disconnect the car from the fridge and battery. Much cheaper and since we can manage with just cooling the fridge before we set off and not being bothered about using the leisure battery since we never go off grid this is an easy solution. Just one connector in the van to disconnect.
What's suprising - but then again perhaps not - is that as far as I can tell the caravan industry is burying its head in the sand about these problem which most be reasonably wide spread and may get wider as time goes on.
Also I wonder what happens in this respect for EVs when towing.
Problem 1 is that due to the Smart Alternators dropping the voltage output when in an 'Eco' mode the fridge doesn't get enough volts to turn on.
Problem 2 is that the Leisure Battery is discharging when towing.
This is a problem reported elsewhere on the Internet and indeed has been mentioned on this forum a number of years back.
What happens is that the Leisure Battery gets connected via Pin 9 to the cars 12v system and effectively the car sees both batteries as one. The Smart Alternator is programmed to cut the output voltage and not charge the battery(s) until they drop supposedly to about 80% capacity at which point it will cut in and start charging.
To me dropping to 80% doesn't sound too much of a discharge but on a few occassions now we've arrived home or on site and found the motor mover wont work because the battery is 'flat' whereas its been on charge, either at home or on site for a number of hours or days.
I need to make a few measurements if I can but I've put this off until now because I didn't want to screw up anything before our last trip and the annual service, which is next week.
There are two potential solutions to both problems:-
1, Install a Battery to Battery Charger - essentially a DC to DC convertor that takes a wide input voltage range (from the car in this case) and produces a constant 13.8v out.
These cost from £150 upwards.
2. Disconnect the car from the fridge and battery. Much cheaper and since we can manage with just cooling the fridge before we set off and not being bothered about using the leisure battery since we never go off grid this is an easy solution. Just one connector in the van to disconnect.
What's suprising - but then again perhaps not - is that as far as I can tell the caravan industry is burying its head in the sand about these problem which most be reasonably wide spread and may get wider as time goes on.
Also I wonder what happens in this respect for EVs when towing.
Or disconnect pin 9. You may not have leisure battery charging, but essentially you will also not have discharging, (or install a suitable diode). At the same time you may get occasional, if not constant, fridge chillling.
John
Having read about smart alternators I bought a cigarette lighter plug-in voltmeter. Running solo after a cold start it can show as low as 12.2V (or on occasion even less than 12V!) which gradually climbs to around 13.5/13.6V and sits there all day.
With the caravan hitched up* and the fridge on the voltmeter sometimes goes as high as 14.9V but usually sits on 14.6V or 14.3V but it never drops below that level. This suggests to me that the ECU update to add towing maybe overrides the smart operation on my car.
Question: has the OP's Qashqai had the ECU updated and/or has the update been done correctly?
*18 plate Passat Estate TDi 150 GT pulling Bailey Unicorn S4 Seville.
With the caravan hitched up* and the fridge on the voltmeter sometimes goes as high as 14.9V but usually sits on 14.6V or 14.3V but it never drops below that level. This suggests to me that the ECU update to add towing maybe overrides the smart operation on my car.
Question: has the OP's Qashqai had the ECU updated and/or has the update been done correctly?
*18 plate Passat Estate TDi 150 GT pulling Bailey Unicorn S4 Seville.
Any VW Group car with a properly coded towbar will initiate towing mode when the electrics are plugged in - this includes changing the alternator charging algorithm so you should get 14+ volts for the fridge.
The caravan Industry has its problems, but in this case it's not the Caravan Industry at fault. They are following the wire coding that had been agreed.
The failure is the car which it seems is being poorly prepared and failing to keep pin 9 fully energised.
A 20A Silicon diode in the feed from pin 9 to the battery would prevent the battery from discharging into the fridge, but at the same time the voltage drop across the diode would reduce the charge voltage supplied to the battery, and it might not fully charge. A more sophisticated solution either using a 20A relay or Mosfet could be arranged to only work when a voltage of 13.0V or more is available from the car.
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I checked when I had the tow bar installed and there is no software update for the Qashqai. I also verified this with a different tow bar installer. In some way I'm glad that there is no update since that would reduce the engine efficiency just to acheive leisure battery charging and keeping the fridge going and I'd rather have better mpg.
The car is aware of having a trailer attached since the towing tell tale light illuminates when the turn signals are on.
I did consider putting a diode in the feed to prevent reverse current flow but that would most likely prevent charging even more and its something I can live without. But not the discharging. Yes, there are other options such as a Voltage Sensing Relay which could have been used in the design of the relay card in the PDU. But they just use an ordinary automotive relay.
The issue I have is that the car electrics are currently an unknown and I'm searching for a manual which may shed some light on it.
The concept of considering the two batteries - car and leisure - as just one breaks down when you consider that the car electronics varies the smart altenator output depending on the charge condition of the car battery. The car battery is sensed but it would appear the leisure battery isn't since if this was the case it would indicate it needed charging as well and the smart altenator would be on high output accordingly. This does raise the issue of duty cycle since the smart altenator would still be working on a high/low output cycle.
While its true that the caravan industry is apparently abiding by some standard it is somewhat lacking in its specification of the voltage requirements at the towing connector. All references are to a 12V system and this is not the case. When the input to the caravan towing connector is 12.9V from my car the fridge will not work. Most likely because of voltage drops along the wiring.
Just for reference the onboard PSU has a rated output of 13.8V presumably to charge the leisure battery if needed but it will also allow for cable voltage drops.
Pin 9 is always energised so technically the car is not at fault since it appears to always provided a minimum of 12V.
The car is aware of having a trailer attached since the towing tell tale light illuminates when the turn signals are on.
I did consider putting a diode in the feed to prevent reverse current flow but that would most likely prevent charging even more and its something I can live without. But not the discharging. Yes, there are other options such as a Voltage Sensing Relay which could have been used in the design of the relay card in the PDU. But they just use an ordinary automotive relay.
The issue I have is that the car electrics are currently an unknown and I'm searching for a manual which may shed some light on it.
The concept of considering the two batteries - car and leisure - as just one breaks down when you consider that the car electronics varies the smart altenator output depending on the charge condition of the car battery. The car battery is sensed but it would appear the leisure battery isn't since if this was the case it would indicate it needed charging as well and the smart altenator would be on high output accordingly. This does raise the issue of duty cycle since the smart altenator would still be working on a high/low output cycle.
While its true that the caravan industry is apparently abiding by some standard it is somewhat lacking in its specification of the voltage requirements at the towing connector. All references are to a 12V system and this is not the case. When the input to the caravan towing connector is 12.9V from my car the fridge will not work. Most likely because of voltage drops along the wiring.
Just for reference the onboard PSU has a rated output of 13.8V presumably to charge the leisure battery if needed but it will also allow for cable voltage drops.
Pin 9 is always energised so technically the car is not at fault since it appears to always provided a minimum of 12V.
By the way, how do you check to see if the vehicle will notify you if a bulb on the trailer is not working?
I would see a notification on the instrument panel. But before every trip out and back we would check all outfit lights prior to setting off.
We check the lights etc before setting off, but I have no idea if the instrument panel will light up ith a warning notification if there is a fault with the trailer lights while towing?
Voltage drop shouldn't be an issue in any outfit - sadly though it frequently IS an issue due to minimum specification wiring in both towcars and caravans - using oversize cables is a relatively easy way to reduce voltage drop but it's generally considered too much work, or too much cost, just to improve fridge performance - as few need charging of the caravan battery from the car.
The towbar installation on my 2011 Hyundai Santa Fe was unsatisfactory - it was done by a so-called towbar specialist which the selling dealer used, but skimped on wiring spec and didn't take the smart alternator into account - I had the wiring re-done by a conventional auto electrician, at my expense, using 80 amp cable and a 140 amp relay - it was overkill numerically but worked very well.
Like many owners, I considered my 2015 VW Touareg as too complex to deal with the same way so I just had a factory-fit towbar specified, which then automatically included fridge circuitry - it doesn't work as well as the Santa Fe but is adequate.
The towbar installation on my 2011 Hyundai Santa Fe was unsatisfactory - it was done by a so-called towbar specialist which the selling dealer used, but skimped on wiring spec and didn't take the smart alternator into account - I had the wiring re-done by a conventional auto electrician, at my expense, using 80 amp cable and a 140 amp relay - it was overkill numerically but worked very well.
Like many owners, I considered my 2015 VW Touareg as too complex to deal with the same way so I just had a factory-fit towbar specified, which then automatically included fridge circuitry - it doesn't work as well as the Santa Fe but is adequate.
How many people have the fridge operating while towing as we have never felt a need for that option even when travelling to Spain?
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