Jump to content

Dometic RMD8551/8555 cooling whilst towing ???


Recommended Posts

Hi

I'm trying to determine if it's possible for this large Dometic fridge to be cooled in the usual fashion on 12v supplied by the towing vehicle whilst travelling. This is a large fridge/freezer and combined with vehicle Euro5/6 smart alternator issues there seems to be some doubt as to whether or not an satisfactory power supply can be provided. 

If you have one of these large Dometic fridge freezers (model RMD8551 or RMD8555) fitted to your van and you are successfully cooling it using 12v whilst towing I would be most grateful for the following information.

  • confirmation of Dometic model (the 2 models mentioned differ only in whether or not auto changeover of power source is included)
  • make/model of caravan and year of manufacture
  • make/model of towing vehicle and year of manufacture

Equally if you are having issues with this model fridge whilst towing I would be interested to know the same information.

Thanks in anticipation.

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

If you read the manual for the RMD8xxx series, it clearly states that the fridge can work on 12v, 230v or gas. Nowhere that I spotted, does it state that 12v is just for maintaining cool, so it appears that “normal” operation can be obtained when on 12v. 
Now, I have one of these fridges (not sure exact model) in a 2018 van, towing with a 2019 model Volvo XC60. 
I can confirm that the fridge certainly is cool, but far from cold, after a two to three hour journey 

Link to post
Share on other sites
Posted (edited)
11 minutes ago, Lost in the wilderness said:

If you read the manual for the RMD8xxx series, it clearly states that the fridge can work on 12v, 230v or gas. Nowhere that I spotted, does it state that 12v is just for maintaining cool, so it appears that “normal” operation can be obtained when on 12v. 
Now, I have one of these fridges (not sure exact model) in a 2018 van, towing with a 2019 model Volvo XC60. 
I can confirm that the fridge certainly is cool, but far from cold, after a two to three hour journey 

Thanks for your reply. I am aware that the fridge is capable of operating under 12v whilst towing - it's a 3-way fridge. My query arises because in my van the fridge is not connected for a 12v supply (other than for control). The caravan manufacturer states this is because of doubts over an adequate supply from potential towing vehicles (due to the size of the fridge and/or Euro6 smart alternator issues).

Hence my interest in whether or not this fridge is working in other vans. Are you confident your fridge is actually working on 12v?

Edited by KnausCol

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
5 minutes ago, KnausCol said:

The caravan manufacturer states this is because of doubts over an adequate supply from potential towing vehicles

Sounds like an excuse.  Caravan manufacturers have no idea, or control over what vehicle is used to tow. 
There are devices, such as the Stirling wild side unit that are claimed to overcome any potential issue with euro6 cars, although as already said, my car appears to operate my fridge successfully. (I really don’t expect it to get cold in only a couple of hours operation)

Link to post
Share on other sites
27 minutes ago, Lost in the wilderness said:

Sounds like an excuse.  Caravan manufacturers have no idea, or control over what vehicle is used to tow. 
There are devices, such as the Stirling wild side unit that are claimed to overcome any potential issue with euro6 cars, although as already said, my car appears to operate my fridge successfully. (I really don’t expect it to get cold in only a couple of hours operation)

I agree with you, a potential car supply problem shouldn't influence a caravan manufacturer in how they install a fridge and I'm pretty confident my car 12v supply is adequate. 

Whether or not a car is actually powering the fridge whilst towing is not always easy to determine particularly if you pre-cool the fridge on EHU before travelling and the journeys are not very long. Vehicle fridge supply often will not  kick in until the engine is running and may even be delayed for a while thereafter when an adequate voltage is reached. Unless there is obvious signs the fridge/freezer has not been running (e.g. stuff defrosted) one might assume all is ok.

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
3 minutes ago, KnausCol said:

Whether or not a car is actually powering the fridge whilst towing is not always easy to determine..........Vehicle fridge supply often will not  kick in until the engine is running and may even be delayed for a while thereafter when an adequate voltage is reached.

I agree that we dont know whether adequate/sufficient voltage is really reaching the fridge when we are travelling.

It is possible to determine whether the voltage reaching the fridge when the outfit is static with engine running though. I havent actually done it but a multimeter test at the fridge terminals is possible - possibly an assistant sitting in the car to keep some engine revs up may be neccesary. I suspect that whilst the circuitry is ok on paper, the voltage losses with the puny cables and long lengths will defeat it. I have heard of some people installing larger section cables with success. Possibly worth doing for a long journey in a hot climate.

Ern

Link to post
Share on other sites

There's so much voltage drop in the runs to a fridge in a caravan, that it's never going to work that well.  I did work them out once, and seem to recall that one can expect about 11v at the fridge.

 

They should work a bit better in a motorhome if they've been wired correctly with 4mm or 6mm cable.

Link to post
Share on other sites

The issue with my van is that the manufacturer hasn't even connected the fridge for 12v operation (for whatever reason)  so regardless of any car voltage supply issues it's never going to work. 

What I was trying to establish was whether anyone with this fridge (i.e. other van manufacturers) has it successfully operating on 12v whilst towing.

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
14 minutes ago, KnausCol said:

The issue with my van is that the manufacturer hasn't even connected the fridge for 12v operation (for whatever reason)  so regardless of any car voltage supply issues it's never going to work. 

What I was trying to establish was whether anyone with this fridge (i.e. other van manufacturers) has it successfully operating on 12v whilst towing.

 

Yes we do.  Last thing I check once car connected and running, is to switch fridge to auto.  We can tell the difference after a couple of hours tow.

Sam :beardy:   RR Sport HSE Dynamic towing Swift Elegance Grande 845

Link to post
Share on other sites
18 minutes ago, SamD said:

 

Yes we do.  Last thing I check once car connected and running, is to switch fridge to auto.  We can tell the difference after a couple of hours tow.

Thanks - and just to confirm yours is a Dometic RMD8551/8555?

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
51 minutes ago, KnausCol said:

Thanks - and just to confirm yours is a Dometic RMD8551/8555?

 Correct.

Sam :beardy:   RR Sport HSE Dynamic towing Swift Elegance Grande 845

Link to post
Share on other sites

We are talking Porsche here - which will be compliant with VAG wiring. VAG provide an accessory cable which goes to pins 9, 10, 11, and 13 on the socket and plugs into the back of the wiring/fuse assembly under the dash. Costs around £100 plus fitting. The fridge cable is plenty big enough to power a tall fridge, Our U4 Seville has a 9330 fridge which draws 170W or roughly 15A and keeps well cool - enough to freeze milk in a trip from N Yorks to Somerset!

 

If the OP wants to get things checked I would suggest he makes an appointment at Horsforth Towbars  in N Leeds. They really know what they are doing and are very helpful.

 

2018 Passat B8 Estate 150GT TDi150 towing a 2018 Bailey Unicorn S4 Seville

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

We are talking Porsche here - which will be compliant with VAG wiring. VAG provide an accessory cable which goes to pins 9, 10, 11, and 13 on the socket and plugs into the back of the wiring/fuse assembly under the dash. Costs around £100 plus fitting. The fridge cable is plenty big enough to power a tall fridge, Our U4 Seville has a 9330 fridge which draws 170W or roughly 15A and keeps well cool - enough to freeze milk in a trip from N Yorks to Somerset!

 

If the OP wants to get things checked I would suggest he makes an appointment at Horsforth Towbars  in N Leeds. They really know what they are doing and are very helpful.

 

If you read my posts you will see this has nothing to do with the Porsche - it has been properly fitted with fully functioning tow bar electrics. The issue is that my caravan doesn't have the fridge connected internally within the caravan for 12v operation, because the caravan manufacturer has deemed a suitable supply from any tow vehicle may not be available. Hence my desire to ascertain whether other manufacturer's caravans with this fridge are installed and working successfully. Just gathering evidence to present to my supplying dealer.

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

Slightly different complection to the op. Our last 3 caravans have been correctly wired to operate on 12V supply from car. 2 Swifts and a Adria. I belive it is the norm for UK caravans and as your Knaus is made for the UK market I would have expected it to be the same.  

Ern

Link to post
Share on other sites

In which case - and apologies for misunderstanding the original - there is a Knaus dealer near Barnsdale Bar on the A1. Pass Barnsdale Bar services on the A1 and take the next exit - A639 - and follow it towards Pontefract. Barnsdale Leisure is about 3 miles on the left and they are a Knaus dealer.

 

Just in case you didn't know.....  :)

2018 Passat B8 Estate 150GT TDi150 towing a 2018 Bailey Unicorn S4 Seville

Link to post
Share on other sites
7 minutes ago, Woodentop said:

In which case - and apologies for misunderstanding the original - there is a Knaus dealer near Barnsdale Bar on the A1. Pass Barnsdale Bar services on the A1 and take the next exit - A639 - and follow it towards Pontefract. Barnsdale Leisure is about 3 miles on the left and they are a Knaus dealer.

 

Just in case you didn't know.....  :)

Thanks for that. Yes I did know, they are my nearest Knaus dealer but unfortunately not the dealer who supplied my new van earlier this year who I am currently in 'discussions' with over this issue.

1 hour ago, Ern said:

Slightly different complection to the op. Our last 3 caravans have been correctly wired to operate on 12V supply from car. 2 Swifts and a Adria. I belive it is the norm for UK caravans and as your Knaus is made for the UK market I would have expected it to be the same.  

My view entirely. It is a van specifically for the UK market and it is fitted with a 3 way fridge. I don't think it's unreasonable to expect it to work 3 ways. I certainly expect it to be at least wired to work to give it a chance!

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

I have that model fridge working fine from my Kia Sorento. I know when it is getting power because I have wired my rear view camera from the same supply wires. No picture = no volts!

Link to post
Share on other sites
2 minutes ago, staffordshirechina said:

I have that model fridge working fine from my Kia Sorento. I know when it is getting power because I have wired my rear view camera from the same supply wires. No picture = no volts!

Thanks - what van might that be?

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
9 hours ago, staffordshirechina said:

I have that model fridge working fine from my Kia Sorento. I know when it is getting power because I have wired my rear view camera from the same supply wires. No picture = no volts!

Ditto re the rear view camera  from the fridge supply on our Lunar Delta towed by a Euro 5 Honda.

Sounds as if the caravan manufacturer is trying to save a few £s.

Link to post
Share on other sites

I have a feeling from reading somewhere that being a euro caravan most don't have a 12v system and the 12v to suit therefore I guess the same with the fridge.

 

Driving a long pickup and having the fridge the other side to the 12v wiring meant my voltage loss was large.

I ran 4.5mm in the car and reterminated the earth's properly , I also ended up upgrading the van wiring save the last length that goes to the 13pin plug.

I also installed a sterling Wildside and wow what a difference. From having a fridge that didn't work, I now have a fridge that will not only keep cool but will also cool down if I haven't pre chilled.

The point of my ramblings is that it's not that much of a difficult job to do and you would be able to use decent size cable . The hardest bit would be getting the cable to the 13 pin plug neatly.

If you take the vents off you should see the large connector with two substantially thicker cables going from that joint into the fridge. They are the 12v feed for the heating element.

From there, if they are joined the non fridge side and trace where they go.

Link to post
Share on other sites

KnausCol and I have been in conversation re this issue since I have the same 'problem'. We don't think it's a question of saving a few pounds since in his and my van, the 12v supply is connected to the power supply unit in the van.  All that is missing are the two necessary wires from the fridge to the PSU.  Therefore he/we are of the opinion that it is a deliberate move by Knaus, possibly to avoid issues of draining either the car or caravan battery. The video on You Tube from Sterling Power re the Wildside explains why.

We are aware of Barnsdale Leisure - they are a lot closer to me than ALV in Tebay- I continue to use ALV - 'nuff said!

Having spoken to the Service Manager at ALV a couple of days ago, they are aware of this issue and it would appear, having checked a new van they have in stock, that Knaus have gone a stage further and the power from the car isn't even connected to the PSU. 

We always have our fridge/freezer on EHU for two or three days before setting off on a trip and even in summer and a 4-5 hour trip, haven't had a problem with the freezer defrosting.  That said, I can see that it would be a different matter if one was contemplating a long trip in the hotter parts of Europe.

VW Touareg Escape towing a 2018 Knaus Starclass 695

Link to post
Share on other sites

2015 Buccaneer towed by a 2018 RR Sport, no problem but fridge is always cold before we set off.

 

Car has LR fitted electrics so the car knows the van is there.

 

Ian

2018 Range Rover Sport AB,  2015 Buccaneer Cruiser.

Link to post
Share on other sites
36 minutes ago, IanV8 said:

2015 Buccaneer towed by a 2018 RR Sport, no problem but fridge is always cold before we set off.

 

Car has LR fitted electrics so the car knows the van is there.

 

Ian

Thanks Ian

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

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...