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How to connect and test Westfalia fridge on 12v DC?
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johnnytod
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PostPosted: Fri Dec 03, 2021 5:15 pm    Post subject: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Hi all,

I bought a Westfalia kitchen unit and I have hard time testing it on 12V DC.
I need some help with that.
The unit is out of the van. I tested it already on propane and on 120v and both worked. But I can't seem to get it to run on 12 v DC. Switch is turned to 12v

Is this the plug with the 3 spade blades in it which is used for the 12V connection?

In this connector there are 3 wires going: black, blue and brown. I understand the black is positive, the blue is negative. What is the brown wire then for?

Does the brown wire have to be connected to something in order for the fridge to work on 12v?

I connected the black and the blue wires directly to a truck battery (also taken outside of the vehicle) but it did not heat..

Is the heating element for the 120 v and for the 12 v one and the same? If that is the case it can't be the heating element as it is already working on 120v. The 10 Amp fuse is also fine.


I understand there is a relay which prevents the fridge to work purely from the battery unless the engine is running and it is getting DC from the alternator.

Is this relay in the fridge or under the driver's seat? How do I jump it?

Since the unit is out of the vehicle, I guess it can't be the relay

Grey cable you see in the picture is the 120 v cable with plug and the black cable with 3 spade connectors you see goes into the same metal box. I suppose that black covered cable with 3 wires in it is for the 12 v DC connection

Any thoughts of what I may be missing to make it work?

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Timwhy
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PostPosted: Fri Dec 03, 2021 5:27 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Not sure if anyone can help but maybe someone can? I have never run my fridge on 12v.
If you can get it to work on 110v and propane then you are ahead of the curve!
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fxr
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PostPosted: Fri Dec 03, 2021 5:31 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

First, the heating elements are NOT the same. If you put 120V on a 12V element, you'd get 100 times the heat out of it and it'd release its smoke PDQ.

So, separate elements.

See the circuit diagram in this thread:
https://www.thesamba.com/vw/forum/viewtopic.php?p=9122836#9122836
It'd be worth reading the whole thread...
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leecat
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PostPosted: Fri Dec 03, 2021 6:04 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

I believe brown runs the fan, so that is 'always on' to 12v and then actually controlled by a thermal sensor (because the fan is needed for cooling on both propane and 110 volt). Blue is the joined ground for both the fan and the fridge, and black is the actual 12v fridge power (thus being 'switched-to-ignition' power from factory) - as running the fridge itself on 12v I believe sucks the battery down in a matter of a few hours.

Therefore to make it run = +12vdc to brown (counter-intuitive to me) and black, and ground to blue. I'm not sure, however, if failing to connect brown to +12v would introduce a failure into the system and lead to the OP's non-working issue.

Please correct me if I am mistaken.
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Ahwahnee
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PostPosted: Fri Dec 03, 2021 6:38 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Timwhy wrote:
...I have never run my fridge on 12v.


X2. Never, in 30+ years. Maybe it is foolishly conservative but I want my batteries to be in top condition when I park at the end of the day. I also like to spare my alternator any extra work.

I have run the fridge 24/7 for a year at a time w/o issue.
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cmayna
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PostPosted: Fri Dec 03, 2021 7:00 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Ahwahnee wrote:
Timwhy wrote:
...I have never run my fridge on 12v.


X2. Never, in 30+ years. Maybe it is foolishly conservative but I want my batteries to be in top condition when I park at the end of the day. I also like to spare my alternator any extra work.

I have run the fridge 24/7 for a year at a time w/o issue.


I use ours on propane during our travels. Never on DC.
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johnnytod
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PostPosted: Fri Dec 03, 2021 10:13 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Do you run the propane also when you are driving?

Is the wind coming through the exhaust pipe not extinguishing the flame? What about safety?

I believe a good deep cycle or li-ion battery can be discharged to half (e.g. to 6 Volts) and recharged without any problems for the battery. I mean that's what the auxiliary battery is for, right?

Regarding connecting the 12V wires:
I figured out the connection of the 12V DC plug - thanks for the hint and diagram. So if you want to bench test your fridge, you should connect the brown and the black wire together and connect them to + in the battery and the blue wire to -. That way the relay closes and the circuit is closed and it starts heating.
I am doing a test now to see how many hours it would run on a normal truck battery until it goes down to 6v. I have been running it already for 2 h 45min and the battery has only gone from 12.3 V to 11.6 V
So based on that run rate I assume it will last at least 6-7 hours until it goes half empty.
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Wasted youth
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PostPosted: Fri Dec 03, 2021 11:00 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

the 12VDC heating element is different than the 120VDC element as stated.

Look at how the wiring comes off the three-way switch and there will be a terminal block where the leads come from/to both heating elements. It is definitely possible to test all three heating methods on the workbench, but I am not able to explain more at this point.

There are other threads that have addressed this.

Both heating elements are available. Your 12VDC element may have failed, like mine. So if you put 12VDC to it and it doesn't work, it may be burned out.

I don't run the fridge on propane while I'm driving - the pilot blows out. I always shift it to 12VDC when I drive.
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cmayna
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PostPosted: Sat Dec 04, 2021 8:28 am    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Guess I've been pretty lucky running on propane during travelling. Maybe I should check to make sure my DC function does infact work.
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DLJ
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PostPosted: Sat Dec 04, 2021 8:39 am    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Yes you can run on propane while driving. If flame blows out it means that you have a leak someplace in the exhaust - intake system. I would check the outside vent cover first.
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PostPosted: Sat Dec 04, 2021 8:55 am    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

As for he correct wiring, here is a link to the diagram in the gallery.


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Should explain the wiring and their colours.
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fxr
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PostPosted: Sat Dec 04, 2021 9:39 am    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

johnnytod wrote:
Do you run the propane also when you are driving?
We always did.
Quote:

Is the wind coming through the exhaust pipe not extinguishing the flame? What about safety?
Never a problem.
Quote:

I believe a good deep cycle or li-ion battery can be discharged to half (e.g. to 6 Volts) and recharged without any problems for the battery. I mean that's what the auxiliary battery is for, right?
Total bollocks. If you discharge a battery down to 6V then you have permanently buggered it. 11.0V should be the minimum - and even that should be avoided as much as possible to prolong a battery's life.
Quote:

Regarding connecting the 12V wires:
I figured out the connection of the 12V DC plug - thanks for the hint and diagram. So if you want to bench test your fridge, you should connect the brown and the black wire together and connect them to + in the battery and the blue wire to -. That way the relay closes and the circuit is closed and it starts heating.
I am doing a test now to see how many hours it would run on a normal truck battery until it goes down to 6v.

Do NOT do this!.
Quote:
I have been running it already for 2 h 45min and the battery has only gone from 12.3 V to 11.6 V
So based on that run rate I assume it will last at least 6-7 hours until it goes half empty.
It's near fully depleted already. Please revise your understanding of batteries before doing these experiments.
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PostPosted: Sat Dec 04, 2021 11:43 am    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

spitsnrovers wrote:
...
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I would expect the most common failure mode for the 12VDC heating would be a break in the element, so an ohmmeter applied to the 2 red wires should be a useful first test.

Have had a flame-out a couple of times through the years - abrupt winds on a very gusty day while driving high speed seemed to have been the cause.
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PostPosted: Sat Dec 04, 2021 11:55 am    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Driving high speeds? In a VW camper? LOL
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PostPosted: Sat Dec 04, 2021 3:18 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

NOTE: the switch shown in the above diagram is as drawn on the label on the fridge. Original Dometic Error!

The drawing is incorrect. It should be a Double Pole-Double Throw switch. The two little bits inside the switch block should both be pointing either up, or down. NOT one up and one down as shown. As drawn simply will not work.

Hope this helps someone else.
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johnnytod
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PostPosted: Sat Dec 04, 2021 10:24 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

Guys, here is my summary of the test.
To recap after connecting the black and brown wires together and connecting them to the battery, the fridge started working.

The fridge worked for a whole 6 hours on a single normal truck battery and which point my battery was completely down.
That's quite more than I expected though and with a deep cycle battery I am sure the result can be even better.

I recharged the battery right up and the battery is fine again.
Here is another interesting thing I found about battery charges:
The charge below shows that at 11.8V the battery already is considered at 0% but I ran my battery until it got to 3v and this provided something like 3 additional hours of fridge time. May not be good for the battery but it still works.

State of Charge Sealed or Flooded Lead Acid Gel battery AGM battery
100% 12.70+ 12.85+ 12.80+
75% 12.40 12.65 12.60
50% 12.20 12.35 12.30
25% 12.00 12.00 12.00
0% 11.80
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PostPosted: Sun Dec 05, 2021 12:26 am    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

While it's true you can run the stock frig from a deep cycle battery pretty much no one does it because it takes a lot of amp hours which equals a lot of batteries to get 24 hours of cooling. The other issue is that comes up is even if you load up on the amp hours how are you going to replace them when you are out camping in the woods. You'll need a lot of solar and sunshine or you'll need to drive many hours to recharge. Also if you do some research on how to optimize loads on lead acid batteries you'll find running them "dead" degrades their performance.

I run my frig on propane and it lasts me an easy week. That also includes propane for cooking and running a heater.
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PostPosted: Mon Dec 06, 2021 1:50 pm    Post subject: Re: How to connect and test Westfalia fridge on 12v DC? Reply with quote

The fridge on 12V takes ~7A. Over 24hrs that's ~170Ah. Going by the rule of thumb that even deep-cycle LA batteries don't like going below 50% of capacity, that means a battery of at least 340AH.

A 300Ah LiFePO4 battery will do it, but would need an *awful* lot of charging to top it up again, especially if the fridge was still connected - you'd need 15A for another 24hrs. If going solar, assuming 5 hrs of good sunshine (the usual figure used for the USA) you'd need at least 850W of useful solar, meaning 1700W of actual panels.

That'd crowd out many house roofs, let alone the complete interior volume of the van...
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