Thinking about a residential fridge.

[38Chevy454]

I also recommend converting to a residential frig. In my old Showhauler, replaced the Notcold 1200 with Samsung RF18. Some small cabinet mods required as the Samsung is a little taller. Also added a pure sine wave inverter, although I understand the Samsung will work with modified sine wave style which are lower cost.
The electric consumption of the res frig is quite low, but adding some additional battery capacity will never hurt. Run the generator once per day was sufficient to get back to full charge and run the A/C in evenings when I would boondock.
My current Renegade Verona came with res frig std, it is also the same Samsung 18 cu ft.

[BCam]

Anybody have links to actual and reasonably scientific power consumption studies when away from shore power? Anecdotal evidence is interesting but I don't want to run a generator for several hours a day and don't want to invest thousands in more solar and batteries.

[AnotherMike]

Originally Posted by BCam

Anybody have links to actual and reasonably scientific power consumption studies when away from shore power? Anecdotal evidence is interesting but I don't want to run a generator for several hours a day and don't want to invest thousands in more solar and batteries.

Easy to calculate.

If someone will post the actual AC current draw of their res fridge you multiply the 120vAC times the amps.

But that draw exists only when it's actually cooling.

Then you have to figure out how many minutes per hour it's actually cooling. That will be determined by how often the door is open, and to a lesser extent the air temperature around it (there is some heat gain through the walls - the insulation of the fridge door and walls isn't perfect).

But once you have the running time it's just 120 (volts) times (actual amps) times (running hours in a day) = Energy usage per day in Amp-hours.
It would be interesting to know the actual amps versus the nameplate amps.

Once you have the amp-hours per day you add 10% for the conversion loss in the inverter, so multiply times 1.1 to add 10%. Yes, 10% may be a little high for a modern inverter, but it's a good starting number to figure energy usage.

Now since the inverter is going to draw 10 amps at 12vDC for every amp at 120vAC you need to multiply by 10 to get the amp-hours at 12 volts.
You also need to measure the idle current of the inverter and convert that to amp-hours... that's wasted power, but it's still amp-hours being drawn from the battery. And smaller inverters generally have much less idle draw than a large inverter... This is why a dedicated small inverter, for the fridge only, is preferred over a large inverter.

So if somebody can provide some hard numbers I've given you a template to plug them into.

Mike

[happy2rv]

I will never willingly have another RV style refrigerator. I used to be paranoid about shutting the refrigerator off if we weren't perfectly level and we've never had an RV refrigerator that was consistently cold enough. Our TT came with a whirlpool residential refrigerator and inverter from the factory and we love it. As far as I know, the only "modification" to the whirlpool was the removal of a conveniently placed screw between the refrigerator and freezer door and replacing it with a knob attached to a rod with threads at the end to keep the doors shut during travel.



Unfortunately, I don't have hard data either, but I can say we have two group 24 marine batteries and just the standard charging line in the 7-way trailer connector, probably 6-8 amps while driving. Our batteries maintain a charge while driving. We've done close to 10 hour days without problems. I haven't done the calculations or real world tests to determine how long we could go without the charge line from the truck though.



As noted, some refrigerators don't like modified sine wave (cheap) inverters.


Many of the newer RVs are coming with 12V compressor refrigerators. These seem like a good option, but I haven't done the research on them. Should be more efficient though. There are also 12V compressor replacements for the cooling unit on the RV refrigerator, keeping the existing shell. This seems like a bad option to me, but some people really seem to like it.

[Sbrownstein]

I have hard data. I ran these tests in my driveway at a couple of ambient temps. Ice maker was off and I didn't open it that much. Ambient temperatures were 76 and 86 degrees. My coach has a monstrous Frigidaire counter depth 23 cubic foot french door unit. It is an energy star unit. Inverter, as shown is a Xantrex 2000 PSW unit. Measurements were taken at 1 minute intervals on a data logger interfaced to my Trimetric SOC meter. At the time I had 4 12 volt factory flooded cell batteries. I now have 4 T-105 Trojans which provide about 25% more storage than assumed in the data. Amperage data is real, SOC data is calculated. Today I could easily go a full 24 hours with the Trojans and stay at or above 50% SOC.

Lots of differences here compared to your "grandfather's reefer." My unit, as with most energy star reefers, has an on-board inverter (not the Xantrex but built in.) This allows the compressor to be run at multiple speeds...the slower the better! Biggest power consumption by far are the defrost heaters. They run for 15 minutes about every 7 hours (it does vary and 7 hours is the spec limit.) Compressor is, obviously, off during the defrost cycle. After that compressor runs for about around an hour at high speed to catch up and then drops to low speed for around 6 hours. Then it all starts again.

Average DC current is around 8 amps. Peak is 50. But you can look at it for yourselves.

I have checked this data against the spec. Defrost heater wattage matches as do last hour wattage compressor draw. You cannot use nameplate data to compare units, but I have had good luck scaling this data using published Energy Star data for other boxes.

Finally, most so called DC compressors (danfoss, etc) are actually componentized versions of this design that come with integral, dedicated inverters. They too are variable speed AC compressors.

[Dutch Star Don]

Scott, quit messing around with all the broken stuff.....just buy a new RV, they come with a nice residential refer.

My dealer is getting in 18 new Newmar coaches next month....you'd enjoy a new Dutch Star! Just think, with the Az address, you'll save a fortune on tax and license versus your previous address.

[FIRE UP]

Originally Posted by Dutch Star Don

Scott, quit messing around with all the broken stuff.....just buy a new RV, they come with a nice residential refer.

My dealer is getting in 18 new Newmar coaches next month....you'd enjoy a new Dutch Star! Just think, with the Az address, you'll save a fortune on tax and license versus your previous address.

Oh thanks Don!
I really needed that bit of *advice* hehehehe. As for AZ and the tax and license savings, well, pretty much not so. In AZ, if you purchase any vehicle, truck, motorhome, motorcycle, space ship, submarine etc, FROM A DEALER, you get charged sales tax. If you purchase any of the above FROM A PRIVATE PARTY, you DON'T pay any used tax!!!

As for the license fee structure, AZ has their own game plan on that too. They look at the MSRP of the coach, then, subtract 60% from that, then, charge you your fees from that point. Then, each year, the fees drop by 16%.

So, when we moved from CA back about 6 years ago, our coach license was up for renewal. We didn't pay it to CA since we were registering all our vehicles etc. now in AZ. Well, the renewal fee for CA was gonna be $380 at that time. But, in AZ, it was right at $600!!!!!!!!!!!! And, based on AZ's way of doing things, our '11 GMC Sierra was around $150 higher than CA, our '08 Honda Goldwing was over $90 higher than the previous fee in CA.

So, no doubt about it, while AZ is cheaper in many ways to live, vehicle licensing IS NOT. About the only good point in relations to registration here in Mohave County AZ, is the fact that, there are NO SMOG RULES here,

In CA, we needed to get the vehicles (pickups and cars) smog checked every two years. And, you could not pay the registration fees UNTIL the smog check was done and it passed. But, here, NO SMOG CHECKS at all. But, that's only in Mohave County. Over in Phoenix and Tucson, THERE ARE SMOG CHECKS.
Scott

[grindstone01]

So let me get this straight, you are not questioning the cost of a new RV, but the licenses and tax cost have got you stopped from the advice of getting a new RV?

[FIRE UP]

Originally Posted by grindstone01

So let me get this straight, you are not questioning the cost of a new RV, but the licenses and tax cost have got you stopped from the advice of getting a new RV?

Cracking up,
No Sir, I'm not questioning the cost of a new RV. Don likes to raz me every now and then, cool guy. In reality, I wouldn't buy a new RV right now even if I had the money to do it cash. As much as we still like to travel some, visit new places and see and meet new people, I really don't know how much longer we might keep up with this.
Ours is paid for and, I've done a ton of remodel stuff to it so, I'm pretty sure it's our last one. And, due to the fact that it's now 16 years old, our license/registration fees have tapered down substantially.

Annnnnnnnyway,
We buzzed on down to our local Lowes and Home Depot and, Lowes had nothing for us in terms of the correct sized fridge and, the one that would fit, was back ordered for over 2 months so, off to Home Depot. They have the EXACT sized fridge that's gonna work perfectly. They even have three different colors and, three of each, YAHOOOOO! So far, the only *sort-a* down side is, there's no provisions for an ice maker in this model.

No biggie. We don't like home made ice from our old RV fridge anyways. We usually take a bucket full of our ice from our home fridge which, is R/O ice and tastes great. When it runs out, we're off to the store to buy some. Anyway, the brand we found is a Magic Chef. $389 for a white one. And, $449 for a *Platinum Steel* one. We're going for the platinum steel one 'cause it would look a ton better. Besides, $450 bucks is a whole lot cheaper than a replacement Norcold N-1095 at around a couple grand.

I could have changed our present one over with a conversion unit but, for this kind of price, and the newest and latest efficiency, to us, it's a no-brainer. We'll pick up the new one tomorrow and the old one is already out of its hole and on the floor of the RV. I think at present, based on my measurements etc, the new one is gonna be a *piston/cylinder* type fit (for all you old grease monkeys). I may have to do some *shaving* of one side of the face frame just to make install a tad easier. We'll see.

Again, I want to thank all you folks that have offered encouragement in changing from a regular RV fridge to a residential one. Can't wait to get this little project all done and go CAMPING!
Scott

[jacwjames]

Check the installation instruction as to what clearances are necessary. They usually have recommended side clearances for rear, top, and sides. This will allow for required ventilation.

There are debates as to whether to seal the rear and top vents, you should do some research on this. I chose to seal up both.

[grindstone01]

Our residential refrig would quit working when the outside temps got into the 30'sF until I sealed off the outside side and roof vent. The specs did call for a narrow operating range of something like 50-90F, which would be normal for a house interior temp range.

[MWeiner]

Originally Posted by FIRE UP

Gang,
Been RVing for decades and, for the most part, have never really had any issues with any of the factory RV (absorption) fridges. Some have cooled more than others. Our coach is an '04 Itasca Horizon 36GD with the CAT C-7 330HP and MH3000 trans. It's around 16 years old now and, well, I'm not sure the fridge is gonna hold out too much longer.

I'm one of those that makes darn good and sure that the coach is pretty much DEAD LEVEL each and every time we camp anywhere. Since *I'm* the one that has to pay for stuff if I get lazy and don't level properly, I take whatever time is needed, to make sure it's level. Now, with all that being said, on our last little trip, we experienced some fluctuation in the fridge temps. Normally, I turn the fridge on at least 24-36 hours prior to leaving on a trip.

The fridge normally get's down to around 35-38 degrees prior to loading it for the trip. Now, living in Lake Havasu City and working with an absorbtion fridge, even though the coach is in its own cave, and is somewhat much cooler than the outside temp, that garage still hovers around 80+ degrees. Some of you boast that your RV fridge gets down to 32 easily in 100 degree weather. Well, I've never been that fortunate. As stated, my RV fridges have worked ok but, never as good as a residential fridge, in that kind of heat.

First, I must mention that, it's a Norcold N1095. In the 9 years and 53,000 miles we've put on this coach, it's never let us down, even in pretty darn hot weather. But, this last trip, we were in only max temps of around 90 degrees or so and, that fridge started out at about 35 degrees at home but, over a few days, it climbed to around 45-47 degrees. There's only two of us and, we've been trained a long, long time ago, to NOT LET OUT ALL THE PING PONG BALLS!!!!!!!! when accessing the inside for food. We open, grab what we need and close it.

So, with all that garb being said, I'm starting to think of a potential change to a residential fridge. I don't think I want to mess with a new cooling unit but, it's not totally out of the picture either. I have (4) 6V golf cart batteries and, a 2000 watt Magnum M/S2020 Inverter/Charger already. From, what I've read about this potential situation, albeit quite a while ago, at least one approach to this is to purchase at least (2) more batteries and, a separate inverter, with possibly even some solar, to power the residential fridge.

Now, we used to *Boondock* or, *remote* camp years and years ago but, we've sort-a migrated to *hookups* in the last few years. That's not to say we won't boondock. That could happen easily based on what's happening when and where we are invited to go or, simply decide to be on our own for a few days. But, normally, we're at hookups. The size of our present RV fridge is around maybe 24" across by, about 4'-5' tall by about 20" deep or so. This is all just a guess since I've not taken any actual measurements.

I'm kind-a assuming that, the cost for a 120VAC residential fridge of about that size, can't be too much money, just guessing. It seems that, based on what I've seen in many new RVs, that many are coming from the factory with residential fridges already stocked in them. They (the fridge makers), must be making the newest ones, pretty darned efficient.

Anyway, I haven't even looked at a standard, RV absorption type replacement just to see what it would cost too. Just starting to think of alternatives.
Scott

Scott, just my 2 cents here... forget residential refrigerators. You might not realize it, but, they need to be level as well....

I did a lot of research and I'm going to give you a pro tip right now.... get a Danfoss compressor... You will not be disappointed and they are designed to be off level up to 30 percent.... I don't think anyone will be camping at 30 percent off level anywhere.

I personally have a Nova Kool, but, I've heard that Isotherm uses the Danfoss compressor as well.

If you were to take a moment and call Nova Kool in Canada, they will explain everything to you.... and why they are a niche company that has been supplying refrigerators for the marine/RV/aviation industry for over 25 years..

Yeah, you can certainly get a residential refrigerator a lot cheaper, but, it will not withstand the rigors of being jostled on the road as well, and it has to be level.

The Danfoss compressor is unique and it's very energy efficient.

Don't waste even one cent on trying to fix that old propane and don't get another propane refrigerator....in terms of the propane refrigerator, think Hindenburg.... it's ammonia, water, hydrogen and propane flame all in one.... terribly inconsistent archaic and mostly all new RV's have a compressor refrigerator.

Good luck.

[happy2rv]

Originally Posted by MWeiner

Scott, just my 2 cents here... forget residential refrigerators. You might not realize it, but, they need to be level as well....
...
Yeah, you can certainly get a residential refrigerator a lot cheaper, but, it will not withstand the rigors of being jostled on the road as well, and it has to be level.
...

Why do you think a residential refrigerator has to be any more level than the Danfoss??? Pretty much if you can stand up in an RV comfortably, a residential should be fine.



I haven't done the research on efficiency, so I can't speak to that. However unless you are going to boon docking a lot, I'm not sure how much of a concern extreme efficiency is.

[MWeiner]

Originally Posted by happy2rv

Why do you think a residential refrigerator has to be any more level than the Danfoss??? Pretty much if you can stand up in an RV comfortably, a residential should be fine.



I haven't done the research on efficiency, so I can't speak to that. However unless you are going to boon docking a lot, I'm not sure how much of a concern extreme efficiency is.

I can't help you.... these guys at Nova Kool can, call them.
You're going to be glad you did. By the way, they are the manufacturer, they don't sell products direct from their operation..

It takes 6 weeks to get a Nova Kool.... not usually in stock, they sell most of what's produced....

Not a regular product on the shelf.