Casita refrigerator needs 12 volts - Page 3 - Fiberglass RV


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Old 12-02-2012, 06:43 PM   #29
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This has been an interesting thread. Even with all the expertise it appears we are unable to determine the actual electrical usage. Why does Dometic make this so difficult?
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Old 12-02-2012, 06:44 PM   #30
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Quote:
Originally Posted by Francesca Knowles View Post
Here's one example of a model for which they do give the numbers.

Francesca
This doesn't give electrical consumption while running on gas - just gas consumption.
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Old 12-02-2012, 06:47 PM   #31
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Raz.....I believe you are right. If nothing else there are indicator lights on the front of the fridge, which would need DC (although very minimal). I still believe there are internal controls needing DC as well.
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Old 12-02-2012, 06:50 PM   #32
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Quote:
Originally Posted by Thomas G. View Post
This doesn't give electrical consumption while running on gas - just gas consumption.
Hmmm...I think you may be right.

There are four sets of numbers there (see below)- how do you interpret that first row ???

At first glance I thought that was for 12v use when on gas/(converted)110...but it's the same as that given for 12v only!

Quote:
Energy consumption @amb temp 25C (kWh/24h) 1.9
Energy consumption 12V @amb temp 25C (Ah/24h) 220
Energy consumption 230V @amb temp 25C (kWh/24h) 1.9
Energy consumption gas (g/24h) 265 g/24h
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Old 12-02-2012, 06:54 PM   #33
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Quote:
Originally Posted by Francesca Knowles View Post
how do you interpret that first row ???

Francesca
Electrical energy consumption is 1.9 kilowatt hours in a 24 hour period when running on AC power at 25* C ambient temperature.
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Old 12-02-2012, 07:19 PM   #34
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Quote:
Originally Posted by charliej View Post
This has been an interesting thread. Even with all the expertise it appears we are unable to determine the actual electrical usage. Why does Dometic make this so difficult?
Charlie it looks like the only way to know how much for sure is to fire it up and plug in a battery monitor..... Please report what you discover back!!
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Old 12-02-2012, 07:53 PM   #35
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Here is a link to the 2454 Installation manual and it sez in at least two places that it won't operate without 12VDC connected.
http://www.dometic.com/f90ce2b0-0aa4...83f3ebf5.fodoc

FWIW: The fuse for the control system is only 3 amps, sugesting that control system draw is somewhere around 1 - 1.5 amps
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Old 12-02-2012, 11:47 PM   #36
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Looks like we've established that refrigerators require 12 to run on LP some don't. It appears to me that one way to tell is if you a control panel with lights, it does require 12 VDC. If no lights, probably no DC is required, (NOTE: I said probably).
It also appears that there's no reference in the manuals to amount of current required. Therefore the best way to find out is to measure it.
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Old 12-03-2012, 05:09 AM   #37
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As a rule if it has no LED display, no automatic starter, no automatic switch, and no interior light it shouldn't need power to work. In the newer fridges it is very hard to find one that doesn't require 12v. Some of the very small 1.7 to 2.4 cu ft are still fully manual but that's about it. Personally I like the auto switch over, auto start, and a fridge light but I can definitely see a niche market for fully manual appliances.
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Old 12-03-2012, 06:41 AM   #38
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My first trailer came with a Norcold N300 3 way fridge. You would light it up and some time later the burner would be out. In an effort to provide convenience, all controls were located at the top of the fridge inside the trailer. To achieve this Norcold used about 3 ft. of wire and over a dozen metal to metal contacts (switches, crimp connections, ect) to connect the thermocouple to the safety switch. The failure occurred because there was too much voltage loss across all those contacts. There was not enough power left to keep the safety switch open. Thus the flame would go out.

To put the controls that far from the thermocouple requires electronics to boost the thermocouple signal and that electronics requires a DC power source. Of course once you do that, why not add a light, fan, electronic temperature controls, indicator lights, micro-controller........ Hence the high current drain when using propane.

From this experience I have concluded that if the controls are outside at the back of the refrigerator, more likely than not there is no DC current drain when using propane. If the controls are inside there is a chance there is. Lights, fans, readouts, ... a sure thing. Raz
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Old 12-04-2012, 11:40 PM   #39
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Electrical units of measure - correction

Quote:
Originally Posted by baron100 View Post
I was advised by a solar dealer that my fridge control in my 2007 Casita uses approximately .5 amp per hour or 12 amps in 24 hours.
I hope this was just a misunderstanding - if not, the solar dealer doesn't know his business.

The correct version would be "approximately .5 amp or 12 amp-hours in 24 hours".
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Old 12-04-2012, 11:52 PM   #40
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Well, you can always ask the authority...

I sent this to Dometic customer service (CustomerSupportCenter@dometicusa.com):
Quote:
Some RV refrigerator models require 12V DC power for controls, even when the refrigeration power is AC power or propane; others use no electrical power at all when running on propane (and no DC power when running on AC). Is there a way to determine which Dometic models - perhaps which series - require 12V DC control power?
This was the response:
Quote:
Any model that has an upper board will require 12VDC power.

We appreciate this opportunity to address your situation, and hope all your future travels are trouble free. Please do not hesitate to contact us any time, to order parts or if we can be of assistance.

Customer Support Center
800 544 4881
RV.Com / DometicUSA.com
Dometic LLC
Not overwhemlingly helpful, but it confirms what Byron, Steve, Raz, etc have said. The "uppper board" is the circuit board at the top front of the appliance which connects to the selection switches, indicator lights, displays, or whatever other nice features need power.
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Old 12-05-2012, 10:50 PM   #41
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Quote:
Originally Posted by Francesca Knowles View Post
There are four sets of numbers there (see below)- how do you interpret that first row ???

At first glance I thought that was for 12v use when on gas/(converted)110...but it's the same as that given for 12v only!

Quote:
Energy consumption @amb temp 25C (kWh/24h) 1.9
Energy consumption 12V @amb temp 25C (Ah/24h) 220
Energy consumption 230V @amb temp 25C (kWh/24h) 1.9
Energy consumption gas (g/24h) 265 g/24h
Tom provided the translation of the first row, which corresponds to a feature item referring to energy consumption according to a European (IEC) standard. Dometic's product page for this model (RF60) gives a fuller version:
Quote:
Energy consumption - according to EN ISO 7371,i.e.: 25 0C / 5 0C:1,90 kWh/24h
That was supposed to be
Energy consumption - according to EN ISO 7371,i.e.: 25 C / 5 C:1,90 kWh/24h
As per Euro practice, the comma is the decimal point. The 5C value would presumably be the temperature maintained inside the refrigerator for the test.

This item is repeated as the consumption for operation on 230V AC. It is not the energy consumption for operation of the controls, because there is no outside-supplied power used for controls - as the specsheet says they are not electronic:
Quote:
Thermostat electromechanic
The other reason it is apparent that this is the energy consumption of the controls is that it is far too much.
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Old 12-05-2012, 11:08 PM   #42
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Quote:
Originally Posted by Francesca Knowles View Post
There are four sets of numbers there (see below)...
Quote:
Energy consumption @amb temp 25C (kWh/24h) 1.9
Energy consumption 12V @amb temp 25C (Ah/24h) 220
Energy consumption 230V @amb temp 25C (kWh/24h) 1.9
Energy consumption gas (g/24h) 265 g/24h
The last three rows correspond to cooling on the three power sources: 12VDC, AC power (in Europe, with their 230V power), and propane gas. None of them include power for controls, because there isn't any - this model (the RF 60) does not have electronic controls.

This model has 110W heaters (AC and DC), which would use 110 W x 24 h/day = 2.64 kW-h/day if running continuously, so it appears to cycle on and off to maintain the set temperature, being on for about 1.9/2.64 = 72% of the time (17.3 hours/day).

The DC row expresses consumption in amp-hours (a useful number for a user considering how quickly their battery will be exhausted) and reflects always-on operation (because as the spec sheet explains the thermostat works only in AC and propane modes) at 12V. This corresponds to
220 Ah/24h x 12V = 2.64 kWh/24h, or
110 W x 24 h = 2.64 kWh/24h

The energy content of propane is 50.35 kJ/g, so the energy consumption per day on propane (assuming that their spec is for propane, not butane) is
50.35 kJ/g x 265 g/24h / 3600 kJ/kWh = 3.7 kWh/24h
The burner uses 11 g/h, which would be 50.35 kJ/g x 11 g/h / 3.6 kJ/Wh = 154 W
That's much higher consumption than with electricity. Propane operation is effective, because a lot of energy is carried in a filled propane tank compared to a similar mass of charged battery and the burner has higher output than the 110 watt electric heaters, but it is not very efficient, presumably because the heat doesn't transfer very efficiently into the refrigerator system.


By the way, this sample model (RF60) should have similar performance to small RV refrigerators, but it is not for use in RVs.
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