Norcold 3-way duty cycle time on 12v?

ElCampo · 10-02-2018, 08:42 PM

Hi all, does anyone know off the top what the normal duty cycle is for the Norcold 3-way fridges installed in the View?

Manufacturer tag shows 17.6 amps at 12v, but does anyone know approximately how many of say 24 hours it will be performing a cooling cycle? Let's just go with average, I know there are variables like how many midnight snacks are consumed, and whether they are consumed in Alaska in October, or Arizona in August etc.

Thanks!

luvlabs · 10-03-2018, 10:31 AM

First off, ignore the sticker as it is listing peak loads. If you have the gas adsorption refrigerator, your refrigerator uses 12V all of the time to run the electronics - the draw is very low. When you are parked without electric power, the refrigerator is powered by propane, when you are plugged into shore power, the refrigerator is powered by AC current and, if you so select, you can choose to run on 12V but that power comes from the alternator not your batteries - your engine must be running.

Given the low current draw of the electronics, I'm not sure how many people have measured it, but it is minimal. While you are cutting amp draws, your propane valve draws a steady 1-2 amps/hour. A major drain. There are homemade and commercial power supplies to reduce the draw.

ElCampo · 10-05-2018, 02:51 AM

Thanks luvlabs,

I was thinking about this in terms of if the fridge were operated from say a battery, does the heater for the absorption just have two states, on / off because it needs to boil the solution, or is there temperature modulation? Compressor fridge definitely has different loads to start the compressor vs run the compressor. Is it the same with this style of fridge? If there is no modulation, how often would it cycle under normal standard ambient conditions? Just looking for a ballpark number

By the sticker, a 24 hour draw at "max" would be 422 amps. What would a realistic 24 hour draw scenario be?

NYBobbo · 10-05-2018, 06:36 AM

I believe the heater, electric or propane is constant with no high or low.

You may consider an ARP control to keep your fridge from burning out due to out of level conditions and poor air flow over the coils. You can search ARP or go to their website for more information.

Ambient conditions vary and the fridge does go through a defrost cycle somewhere around every day to day and 1/2 - someone else may have the actual cycle on that.

If you plan on using electric from your batteries perhaps the 422 amps on the sticker is correct in any kind of hot climate and less if it's cooler. I think you will have to experiment with yours, let us know how it goes.

old_engineer · 10-05-2018, 07:51 AM

The heater elements in an absorption refrigerator are either on or off. The 12V heater is primarily intended to be used when your are traveling and hooked up to the tow vehicle. When at camp you would use either AC or gas to cool the unit. The control boards themselves don't pull much current and if similar the Norcold is similar to my old 3-way Dometic would be less than an amp.

luvlabs · 10-05-2018, 08:59 AM

To make this real simple, I don't believe there is a way to run the Norcold absorption refrigerator on 12V unless the engine is running. I don't believe it is on the inverter circuit either. So, your refrigerator is either propane or 120V AC (shore power or generator).

ElCampo · 10-06-2018, 05:58 PM

To clarify, I'm in the process of installing a decent solar system and battery bank. My initial thoughts were to let it remain as installed, which for boondocking would mean it will run 99% of the time from propane. I am considering the implications of reconfiguring the wiring to add 12v input from the battery bank rather than the alternator, or 120v from the inverter. My general inclination is to leave it as is, but if the draw isn't obscene I see no real reason not to give it a 12v boondocking option. I'm new to absorption fridges so I'm trying to get some user data for actual run times in an average climate. If it runs over 50% of the time, it's a non starter. If it only runs say 10-20% of the time, I'd start getting pretty interested, even if it were just set up to run from 12v when the sun is shining.

powercat_ras · 10-06-2018, 06:46 PM

I would assume 160 - 240 Amp-hours per day , depending on weather and how much you open and close the door / doors.

The solar investment to produce that much extra solar per day compared to running on propane and buying the propane to run the refrigerator will not give a very good payback.

ElCampo · 10-06-2018, 07:56 PM

True, at 160-200 amps per day it would not make sense. Do you think winnebago would be receptive to trading out the absorption for something with a swing compressor or danfoss?

It would no question at that point!

Then again, it's easy enough to set up a load relay to provide 12v battery power for maybe 6-8 hours of the day (let's go with daylight hours) and greatly supplement the propane especially during the warmer sunny hours. I could give up 40-80 amps per day for the fridge. The solar is getting installed regardless of whether the fridge is viable.

NYBobbo · 10-07-2018, 11:28 AM

I'm sure you can purchase a new fridge and sell off the old (new) one. If you have deep enough pockets you have many options. Why not try what you have and see if it's needed. You can plan all day long and setup and work on things to get it perfect, but it's a waste if you don't use it. Go camping.

ElCampo · 10-07-2018, 04:29 PM

Quote:

Originally Posted by NYBobbo

I'm sure you can purchase a new fridge and sell off the old (new) one. If you have deep enough pockets you have many options. Why not try what you have and see if it's needed. You can plan all day long and setup and work on things to get it perfect, but it's a waste if you don't use it. Go camping.

Just theorizing since I'm on the road for work at the moment and 99% of my solar has arrived and is patiently waiting for me to install it!

I'll be home in a few days, and we'll be on the road with it in a few weeks time.

I actually enjoy the thinking and innovation part of all this stuff because it's applicable not just to me, but to others looking to do similar things and generally the industry improves when needs are filled.

If you consider that when you live on a sailboat and have a proper solar setup that can run refrigeration and desalination, the only time limiting factor for boondocking is food, which a lot can be carried, and a lot can be caught. I'm trying to get as close to this as possible because I like my freedom. It looks like in this case, the time limiting factor will be either fresh water, or propane. I guess I'll see how the water supply works out, and then take another look if warranted.

Thanks for the input.

Ray,IN · 10-10-2018, 10:48 PM

You may download the Dometic service manual for your frig from bryantrv.com.
It will have all the information you need in it other than installation instructions, which is a different manual.