Jump to content

Fridge electrics when towing


Recommended Posts

Not that old chestnut I'm sure but,,

 

We've just taken delivery of our new Buccaneer a few days ago  & it's great, just a couple of minor irritations

 

The fridge alarm shows when connected to the car to show there's no 12v supply.

 

My car (2020 BMW X5) has a factory fit lowball & electrics.

 

The car dealer's checked the towbar electrics & said it's giving 12v supply to the fridge pin (no 10  from memory) when under load but the caravan fridge seems not to believe me!

 

I've asked the supplying dealer but they're hopeless. On one hand they say it was checked at the PDI & then on the other hand say I need to bring the van in so they can check it!!

 

Does anyone have any idea/knowledge of how I can check the fridge under power from the car.

 

I have of course tried running the engine past 1,500 rpm (the car dealer says it's not necessary on this model car)  to no avail:(

 

Help pls,,

Link to post
Share on other sites

If it were me, I would get all the towbar electrics checked out at a good independent auto electical place, or an independent tow bar fitter, my friend spent weeks going back and forth with BMW dealer with similar problem and eventually turned out that factory fit BMW towbar and electrics were not wired correctly to run fridge on move, not sure if they are the same now,but as I said get it checked independently

Link to post
Share on other sites

I would agree with Woodsieboy, car dealership engineers or so called autoelectricians generally seem to be wanting when it comes to caravan electrics and in particular, feeds for fridges and AL-KO ATC. For the relatively small cost of having them check it over, their expertise is worth it.

 

Dave.

Link to post
Share on other sites

Cheers guys,
 

I did speak with a local auto electrician who does tow bars & trailers

 

he talked in a language I didn’t really understand but the upshot was he didn’t want to play with my electrics for fear of causing an issue that may invalidate my cars warranty 

 

 

Link to post
Share on other sites

I had a 2016 BMW520D with a factory fit retractable tow bar and that didn’t have fridge wiring. Apparently this is “the norm” with BMW. There wasn’t even a pin to connect to in the 13 pin socket!

2018 Volvo V90 and 2018 Swift Sprite Quattro EB

Link to post
Share on other sites

Car dealers are,  in my experience,  woefully ignorant when it comes to towing equipment.  Many German cars with factory fitted tow bars came with just the wiring for road lights.  I once bought a new Golf with tow bar and discovered this to my cost.  Ever since,  when ordering a new car with tow bar,  I have specified that it will have electrics fitted for all lighting,  plus  wiring for fridge and trailer battery charging.

      John.  

Link to post
Share on other sites

The fridge wiring will only be live if the engine is running but it sounds like this has been checked. It should be easy enough though to take the cover off the plug and see if it has a wire to terminals ten and eleven which are the ones you need.  

As Leedslad says most dealers have no idea about towing and the electrics involved so I would not rely on them for advice.  Standard wiring is normally for a freight trailer, the extra for a caravan is not included, so you do need to specify this. Many dealers simply farm out fitting to specialist tow bar fitters so very little point in getting one from the dealer unless it is a factory fit and not fitted over here.

It is possible there is a fault at the caravan end though so this needs to be checked as well.

Link to post
Share on other sites

Your best bet is to make an appointment and take it to Horsforth Towbars who <really> know what they are doing. I have had three bars fitted to Passat Estates there and have never had a moments problem.

 

If you go up to LBA and turn in as if going into the airport, then continue down to the bottom and turn right. When you get to the T-junc turn left down to the Old Ball roundabout. Continue forward left towards the station and take the first turn into the right between shops, HT are at the back.

Link to post
Share on other sites
29 minutes ago, Wildwood said:

 

As Leedslad says most dealers have no idea about towing and the electrics involved so I would not rely on them for advice.  Standard wiring is normally for a freight trailer, the extra for a caravan is not included, so you do need to specify this. Many dealers simply farm out fitting to specialist tow bar fitters so very little point in getting one from the dealer unless it is a factory fit and not fitted over here.

 

 

Unfortunately with BMW it is down to BMW themselves.  While in Europe there's no demand for fridge wiring they used to do a kit to upgrade UK spec cars but decided to drop it because most of Europe didn't need it......  I managed without it, we found that chilling the fridge down before and putting a frozen bottle of water in there for longer journeys was fine, if it hadn't have been for it being on a 3 year lease I would have got it sorted had I been keeping it for longer.  My car previous to that was a Mercedes which came with the Mercedes fold-away tow bar and that had all wiring including the fridge supply.

 

I fitted an aftermarket tow bar to my current Volvo with a dedicated wiring kit from PF Jones and that had everything included thankfully, even a special feature that cut the fuel gauge power supply when the caravan was plugged in...........  THAT was down to an incompetent fitter (not me!).

 

 

2018 Volvo V90 and 2018 Swift Sprite Quattro EB

Link to post
Share on other sites

Both my previous Audi and current Porsche had factory fitted tow bars and neither had a connected fridge circuit. It's just not the norm in Germany and they don't seem to think it necessary to supply proper towing electrics for the UK even though obviously the cars are specifically built RHD for our market.

Even if the towing electrics include the necessary circuits you may also fall foul of the smart alternator issue. Modern Euro5&6 cars employ smart alternators to help meet recent emissions targets. Basically the alternator only outputs full voltage until the car battery achieves a pre-set level of charge (usually about 80%) before reducing output. This is to allow capacity in the battery to receive charge from regenerative braking. The reduced voltage output and losses due to the length of wiring to the caravan may result in there being insufficient voltage to power the fridge. I can see this quite clearly in my car because it has a voltage output display on the dash and an 'intelligent' smart alternator. When driving solo the alternator output starts at 14.8 volts but reduces and fluctuates according to the battery's charge state often being as low as 12.5v. However my car intelligently identifies when the caravan is attached and maintains a full 14.8v output all the time. Not sure how your BMW will operate but worth finding out!

Life is not a rehearsal . . .:)

Porsche Cayenne S Diesel & Knaus StarClass 695. Previously Audi S4 Avant & Elddis Super Sirocco

Link to post
Share on other sites

The number of times as was asked"Have you turned the fridge onto car" I wired a 12 volt LED into the 12 volt circuit of the fridge. The LED was fitted into the front marker of the van, I could see this in the mirror so was able  to say "Yes I have"

Link to post
Share on other sites

My Tiguan came fully wired so not all German cars come part wired.

 

Best way to check you problem is to check for voltage at the rear of the fridge, could just be voltage drop, if it's wired for the fridge

Link to post
Share on other sites

Some great advice above. Intelligent alternators typically only supply enough power for the demands of the car therefore the caravan might not get a look in. I guess this depends on just how intelligent the car is. 

Link to post
Share on other sites

The fridge supply from the car also operates the habitation relay - cutting off the 12 volts inside the van.

A down and dirty way to check the habitation relay is operating (and therefore getting a fridge supply) is to switch on an interior light. Start the car and see if the light goes out. (Please correct me if I'm wrong here!)

I also understand from previous posts on here that if you switch on your proper headlights on your Smart Alternator car, you'll get a higher output from the alternator, which may well kick in the fridge,...

 

Link to post
Share on other sites
16 hours ago, Woodentop said:

Your best bet is to make an appointment and take it to Horsforth Towbars who <really> know what they are doing. I have had three bars fitted to Passat Estates there and have never had a moments problem.

 

If you go up to LBA and turn in as if going into the airport, then continue down to the bottom and turn right. When you get to the T-junc turn left down to the Old Ball roundabout. Continue forward left towards the station and take the first turn into the right between shops, HT are at the back.

Cheers, I'll give them a try. as I said the car's been to the dealer (after I bought it) who confirmed they'd tested it did have power when connected to their test/load board.

Link to post
Share on other sites
14 hours ago, KnausCol said:

Both my previous Audi and current Porsche had factory fitted tow bars and neither had a connected fridge circuit. It's just not the norm in Germany and they don't seem to think it necessary to supply proper towing electrics for the UK even though obviously the cars are specifically built RHD for our market.

Even if the towing electrics include the necessary circuits you may also fall foul of the smart alternator issue. Modern Euro5&6 cars employ smart alternators to help meet recent emissions targets. Basically the alternator only outputs full voltage until the car battery achieves a pre-set level of charge (usually about 80%) before reducing output. This is to allow capacity in the battery to receive charge from regenerative braking. The reduced voltage output and losses due to the length of wiring to the caravan may result in there being insufficient voltage to power the fridge. I can see this quite clearly in my car because it has a voltage output display on the dash and an 'intelligent' smart alternator. When driving solo the alternator output starts at 14.8 volts but reduces and fluctuates according to the battery's charge state often being as low as 12.5v. However my car intelligently identifies when the caravan is attached and maintains a full 14.8v output all the time. Not sure how your BMW will operate but worth finding out!

I agree with your comments, the BMW tech guy I spoke with told me the same, he said it's not possible to test with a  multi meter, the car needed to be connected to the trailer socket & under load, he confirmed he'd tested it & it works. The supplying dealer for the caravan hasn't actually got any idea & said I've got to bring the van in to them.(:

 

Link to post
Share on other sites

My Passat bought used with factory towbar was not wired for the fridge. Cost about £150 to sort it. I have read on a number of forums that switching on the headlights will trick the smart alternator into supplying power to the aux/fridge feed. I have long had the habit of switching on my headlights when towing (not sure what prompted the habit) so with my hybrid Volvo the fridge seems fine when towing. 

Link to post
Share on other sites
2 hours ago, Flatcoat888 said:

 I have read on a number of forums that switching on the headlights will trick the smart alternator into supplying power to the aux/fridge feed. I 

 

Doesn't work if you have LED headlights though:( not enough current draw! 

Experience is something you acquire after you have an urgent need for it.

Link to post
Share on other sites
4 hours ago, Mr Plodd said:

 

Doesn't work if you have LED headlights though:( not enough current draw! 

 

Headlights on makes zero difference to my car when towing but then its usually over 14volts when connected to the caravan.

I need 14.3 volts minimum to get 12volts to my fridge when under load, despite upgrading the caravan wiring to 10mm for the fridge. 

Swift use only 4mm for the fridge wiring for a 170watt fridge.

Link to post
Share on other sites

On my caravan I can take the fridge vents off and put a multimeter on the 12V wires. When car is connected and fridge off I get 14ish volts. When I switch fridge to car the voltage is 10v so I know it is drawing current. 

Link to post
Share on other sites
8 minutes ago, halifaxdan said:

On my caravan I can take the fridge vents off and put a multimeter on the 12V wires. When car is connected and fridge off I get 14ish volts. When I switch fridge to car the voltage is 10v so I know it is drawing current. 

Thanks Halifax Dan, I'll give that a try:)

Link to post
Share on other sites
1 hour ago, xtrailman said:

 

Headlights on makes zero difference to my car when towing but then its usually over 14volts when connected to the caravan.

I need 14.3 volts minimum to get 12volts to my fridge when under load, despite upgrading the caravan wiring to 10mm for the fridge. 

Swift use only 4mm for the fridge wiring for a 170watt fridge.

Plus it runs through 3 (on my Swift caravan) block connectors from the fusebox at the front to the fridge at the middle. Only needs one dodgy connection to drop the Voltage at the fridge, as was my case.

 

 I went down the Sterling Wildside route but that was primarily to  give the correct charging algorithm to my lithium battery, after upgrading the wiring to the fridge it now run runs on 12V as it should. That was an additional bonus from my original install.

Edited by Harrib0
Link to post
Share on other sites
2 hours ago, halifaxdan said:

On my caravan I can take the fridge vents off and put a multimeter on the 12V wires. When car is connected and fridge off I get 14ish volts. When I switch fridge to car the voltage is 10v so I know it is drawing current. 

 

If its dropping to 10v under load you will not be getting the rated power you need 12v for that.

Link to post
Share on other sites

Yeh I know. My freezer doesn’t hold temperature while driving. It’s not so bad that I want to rewire things but not ideal.  

Link to post
Share on other sites

In my experience some auto electric ‘specialists ‘ haven’t got a clue about the requirements for towing a caravan. After trying several times to get the people who fitted my towing rig to get it right, I discovered myself that they’d taken the feed to both pins 9 and 10 from the cigar lighter type socket in the tailgate. The wiring to that is a mere 10 amps rather than the 25 amps needed and runs from the ignition, so there was no permanent feed to pin 9. Neither the ATC nor the fridge worked properly. They thought the solution was to rewire the socket to bypass the ignition, which caused further issues, including a constantly clicking relay for the fridge . In the end I gave up and got Carma Automotives to come out and fix it. Next time I change vehicle I will get Carma to do the job from the outset.

Edited by MalH
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...