Observations on the Westy Fridge

[WhirledTraveller]

Now that I've got my aux battery wired up (to an old, weak, Honda Civic car battery for now...) I've been playing with the various electrics. The PO had never used any of it and the fridge probably hadn't been run in 10 years or more. The electric panel worked with the exception of the battery gauge. I took the gauge out to test it and it's definitely dead Now I'm looking for a replacement, I'd like to go digital but not modify the cutout... might not be possible.

However the fridge worked great! I stuck an indoor/outdoor thermometer in it, and with an interior temp of 56 degrees the fridge was down to 25 in just a couple of hours. (On shore power). Woohoo!

I made a few measurements with my DVM which might be of interest to some of you. The resistance across the fridge heating element is 2.1 ohms. On shore power, the voltage across the element is 9.7 volts and under battery power it was 9.3 volts (with 11.9 measured at the battery under the load).

This means that the fridge is drawing about 4.5 amps. It also means that I'm losing 2.6 volts or over 20% efficiency just to the wiring /switches/ fuses etc.

Might be a rewiring project in my future...
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[oisak]

You can check RV sites for electric gauges and power inverters. Also marine sites are a good source for this.

[WhirledTraveller]

Followup... I didn't like all that voltage drop in the wiring so I did a little investigating. I found that the stock way the Westy is wired the negative side follows a tortuous path back to the battery, and the stock wiring from the fridge to the first connector (only 2 feet or so) is very low gauge.

So I ran a 12 gauge wire from the negative side of the fridge heating element directly to a solid ground. I also ran a 12 gauge wire from the positive side of the thermostat directly to the first connector (essentially bypassing the Dometic wiring harness). The voltage across the element (under battery power) jumped from 9.3 Volts to 10.6 volts.

Might not seem like much but consider this...

Before, the fridge was pulling 53 watts from the battery and only using 41.

Now, the fridge is pulling 60 watts from the battery and using 53.

12 more watts of cooling power, with only 7 watts more battery drain.

All this for 15 minutes work and no permanent modifications to the wiring.
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[fusername]

ah nerds and bussess, such a combo.

I just noticed you a re local, so here's a pointer. go to the MIT fleamarket, its every month durnign the warmer months, there i s a guy with 4 million voltage and amp meters, you could put on in the panel, as i figure the stock thing must just be a volt meter.
I'm actually about to tear apart that wiring, as my fridge doesnt exist, po removed the element, and redo the entire panel so it has a line input for ipods, an on off switch for batt power/aux, an inverter, etc etc.

if your ever interested in swapping notes pm me, we could do some real damage together im sure. and welcome to the samba!
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[WhirledTraveller]

Hey! I resemble that remark!

I've been to the MIT fleamarket several times. Conjures up dreams of creating a mad-scientist lab in my basement.

I'm also looking to make some sensible mods... but I want to preserve the stock look as much as possible, so I want everything to be hidden behind the scenes.
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[typesoneandtwo]

[Duncwarw]

4.5A? Wow, that's about half what I'd expect.

In my case, the fridge doesn't cool well at all on DC. It may be that the DC side of mine needs looking at.

On AC or LPG though it gets plenty cold.

Good info, thanks.
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“To find yourself, think for yourself”
Socrates, 470 BC - 399 BC

[Karl]

[Duncwarw]

Ah that explains it. Mine's a 3-way from a Vanagon.

Thanks Karl.
_________________
“To find yourself, think for yourself”
Socrates, 470 BC - 399 BC

[WhirledTraveller]

Since I did the wiring mods the amp draw is now 5 amps. FWIW the sticker on the side of the fridge says 5.4 Amps at 12 volts...

I'm planning on putting a 100 AH deep cycle reserve battery in. Then I figure I can run the fridge for 10 hours to a 50% discharge (about as far as you want to go for battery longevity).
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[pittwagen]

Rather than start another fridge thread I have revisited this one and have a couple of questions I hope someone can answer.

I have a fridge from a 74 Westfalia that appears to be working quite well. I really don't think it was used much - still has the ice cube tray! So far I have run it only on 110V through the stock converter at the back of the fridge which delivers 12v to the heating element. It cools to about 45-50 degrees below ambient air temp. on the max. setting and about 25 degrees when set just past the "on" position. I haven't measured the amps yet on the various settings. Lowest temp measured in the middle of the fridge was 20F from an ambient temp of 70F using a good quality thermometer.

I've looked at new units and while they draw much less power, it would be nice to keep this one going for now and hopefully improve its efficiency.

The 12v wiring from the battery is as it should be - bypassing the variable setting switch and going to the heater via the 12/110 switch.

I also don't spend much time where there is 110 power. Given that I may not always need max. cooling I would like to wire the 12v from the battery through the variable setting switch. Is there any reason why I can't do that and at the same time using a much heavier gauge wire?

Why did VW not do this to begin with?

Seems to me that if this was the case the unit would draw considerably less amps from a deep cycle battery. Hopefully I will be adding a decent solar panel to support this as well.

Also, has anyone experimented with added cooling fans to remove the heat from the back of the unit?

I am building a custom setup for the fridge location - similar to the Vanagon with vents on the left bottom, left side top and across the top rear. This will be in a stand along cabinet behind the driver's seat with a sink and cupboard. The fan would pull cool floor air from the bottom and up the back over the cooling unit. I'm going to allow a 2" air space under the unit for air flow.

Thoughs and comments please.

[fusername]

in a vangon they added a fan down below the hot coils to move air. when you run your fridge make sure the grill on the top of the cabinet is clear, and that the grill on the floor near your feet is clear, air should circulate through there. I am wishing I had rememebered this thread and checked my voltage drop, i spent 2 weeks in utah living out of the bus with friends and the fridge only stayed cool enough to stop things from spoiling. we ran it whenver the car was on. never got as cold as i rememver it getting in my driveway a year or two before hwen i installed it. I have a fridge from a 79 in my 77, which appears to have a 1110 volt heating element, as it is the fridge with a selector switch in the cabinet. I am a little shocked to seekarl wrong here, so I may trace the wires around next time I am bored. I also need to clean out the cob webs. glad to see a real number on fridge draw, as I am living from the bus again and was thinking investing in a solar panel would be wroth it so i could run the fridge, but wasn't sure what size would be needed to run it from time to time, all the numbers I could see were 7 amps, which is clearly wrong. my ammeter is sadly dead, never lend out good tools folks!
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Need something custom bent up? shoot me an email, maybe we can make it work!

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[busdaddy]

[tayfoss]

Love your post, though the content is entirely inapplicable to the fridge in my bus. My 1970 Westfalia icebox, is just that. There is a tray to hold a block of ice and a little drainage line for the water when it melts. Why invent a pen that can write in space when you can just use a pencil?

Cheers,
Taylor

[kmmcdonald]

Will the refrigerator work (run from city power) when the auxiliary battery is not in the bus (78 Westfalia)?

thanks

Keith

[pittwagen]

Here's the best pic I could find of the switches.

The sources are both 12v. The one shown as 12v in the pic comes from the battery. The one shown as 110v comes from the converter but is only 12v.

The switch at the bottom is the variable output swith hooked to the capiliary tube and rated at 250v.

My question is why can't the 12v battery source and the 12v converter source go through this switch and connected at the wire terminal and effectively bypassing the 12v/110v switch above.

All the wires eventually go to the blue connector and on to the heater.

Interestingly there are 2 wires coming from the heater that aren't connected - 110 volt source??

[pittwagen]

Here are a few more pics:

Fridge transformer/power converter:

Another of the fridge rear - note 2 unconnected wires coming from the heater - lower left.

Anyone know why the battery wires and the converter wires (which both supply 12v) can not be spliced together so as to be able to use the variable output switch - lower right?

[busdaddy]

Maybe it's time to pull the heaters out and see which one is disconnected and test it for continuity.
Not all 74 fridges have that transformer, I'm beginning to suspect it's a fix when the 110V heater burns out to utilise the 12V heater in it's place, all that have the transformer also have the cut wires.
The thermosat isn't a variable control, it's a simple on/off switch controlled by a capilliary tube, the pressure it turns on or off at is varied by changing the spring pressure in the control when you turn the knob. As such there's no reason why it can't control the 12V side directly.

You may have to change how the wires on the 110V/12V switch are arranged to switch input sources or swap some wires downtream from it, the diagram on the fridge is pretty cryptic about what it does internally.
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