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 Post subject: 110 Volt Fridge
PostPosted: January 30th, 2017, 5:56 pm 
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Joined: August 8th, 2015, 11:54 am
Posts: 190
Location: Santa Cruz, CA
Well, as with most Chinookers I seem to never run out of ideas to modify my rig. I'm sitting in a motel room in Springfield, Oregon while AM Solar installs 460 watts of solar panels, a 350 watt inverter, new charger, 2 - 6 volt AGMs rated at 300ah and some additional 12 volt DC outlets. One goal of this set up is to be able to camp off-grid without running the generator except as needed for the A/C, but my ultimate goal is to replace my Dometic 3 way fridge with a 110 volt residential fridge. We camp where temperatures are often above 100 degrees during the day and the Dometic can't keep up with that, with fridge temps rising to almost 50 degrees during the day. I've seen a 110 volt 7.3 cubic foot fridge/freezer online that appears to be the right size to fit in the existing opening and the only electrical spec I can get on it is that it draws 34 watts. I know that Engels and ARBs have very low current draws but all of them are too small and most make you choose between having a fridge or a freezer. My questions are as follows:

1. Do you think this new solar system will have enough juice to run a 110 volt fridge?

2. Has anyone switched to a 110 volt fridge and if so what size? How did it work out?

3. Does anyone have recommendations as to a particular brand of small residential fridge?

Thanks!

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 Post subject: Re: 110 Volt Fridge
PostPosted: January 30th, 2017, 6:56 pm 
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Location: Santa Cruz
I have a 4.5 cubic foot Magic Chef residential refer that I power with 200 watts of solar, a 1k inverter, and a pair of golf batteries. I would have it no other way. This system covers my other 12V needs as well.

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 Post subject: Re: 110 Volt Fridge
PostPosted: January 30th, 2017, 8:53 pm 
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How were you able to install 2 golf cart batteries? I assume these are 6 volts. All the ones I have looked at are too tall for the battery compartment.


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 Post subject: Re: 110 Volt Fridge
PostPosted: January 30th, 2017, 9:12 pm 
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Location: Santa Cruz, CA
Hey Scott - you went with a 1kw inverter. Should I be worried that AM Solar is going with too small an inverter? They're specing
a 350 watt inverter. I should add that I'm not planning on running anything else but the fridge and a laptop charger off the inverter.

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 Post subject: Re: 110 Volt Fridge
PostPosted: January 31st, 2017, 4:53 am 
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Joined: October 20th, 2015, 6:57 am
Posts: 548
Location: Northern NJ
Do you Chinookers who depend on solar always park out in the open? Do you only travel in the Southwest or ?

I would think that in the parts of the country with tree cover, rooftop solar would be basically useless. At least, it is for me with even part shade.

Thanks,
Kevin

PS 350W inverter sounds small to me, as I would double whatever I needed, but they're the experts.

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 Post subject: Re: 110 Volt Fridge
PostPosted: January 31st, 2017, 9:27 am 
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Joined: August 10th, 2014, 6:06 am
Posts: 134
BAbbling out some recollections of posts past,I recall a discussion of marine refers,that ran efficiently that blue posted using danfoss compressors,( but he will comment for himself eventually).I agree that Am solar,are the experts but if you are breaking the bank you don't want to have to upgrade in the near future.HandyBobs solar blog highly recommends Magnum inverters,and his basic system features their 1200 watt unit,if I recall correctly.Not being an electrical engineer,I rely on others,and his general recommendations have worked well for me.Perhaps or perhaps not something to investigate,pertinent to your query.Rooney


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 Post subject: Re: 110 Volt Fridge
PostPosted: January 31st, 2017, 9:47 am 
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Joined: July 31st, 2014, 1:01 am
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Location: 1999 Concourse
kdarling wrote:
Do you Chinookers who depend on solar always park out in the open? Do you only travel in the Southwest or ?


I like to camp in the shade - especially in summer. What I do is have a pair of 100 watt panels that I can set out wherever is best (on a ~30' tether). So far the only time that hasn't let me put them in the sun is when I visited a friend in the NW and parked in his backyard, behind a huge row of trees, and under a carport :lol: At that point I plugged in! But that's the only time I've plugged in since I set up my panel system in the spring of 2015. Having free-standing panels also works nicely in winter. Where I typically camp then there is not much shade, but the sun is on a low angle and the hours of sunlight in a day are much fewer. However I can easily angle the panels -- both toward the sun and at the 45º or whatever is best to match the sun's path. Then I can park the Chinook however I want to for views or etc. at a given site (vs. needing to angle it a certain way).

I'm running a not-huge compressor refrigerator (DC, Danfoss BD-35 compressor) on those 200 watts and still get up to 100% on any day with a reasonable amount of sun. I can also "catch up" reasonably quickly after a period of cloudy/rainy days (although there's a limit - a week of rain would be a problem - but then I'd probably leave at that point!).

I have 270 watts (two 135 watt panels) slated for the roof but I've been lazy about installing them as the 200 watts of ground panels are really all that I need. BUT, it's inconvenient when on the road or stopping over at parking lots enroute. Once I put the roof panels on I probably won't have to put the ground panels out unless there is bad weather or I'm parked in the shade.

The panels I have are the thin (formerly known as flexible) ones and they stow well right up against the back of the driver's seat when on the road.

As far as sizing an inverter/AC (110) fridge, a couple of things to consider:

1) There will always be a bit of inefficiency when using an inverter, because some power is lost in the conversion process/running the inverter, but as long as you can account for that (both in sizing and in re-charging capacity), then fine.

2) AC refrigerators are typically not meant for "being underway" (vs. many DC refrigerators come from the marine market), so you may have to fit door latch(es), put fiddles on shelves (or be careful when you open the door), a mounting method (the DC ones typically come with a mounting flange) etc. Also things like self-defrosting might be undesirable (power draw).

3) You can do the basic power conversion yourself. If you start with watts, which is generally on any appliance. Then you can divide the watts by the voltage you are using. For example, if something draws 800 watts, that means it will draw about 7 amps AC and/or about 66 amps [sorry, initially I had typed watts by accident] DC. And of course that would need at least an 800 watt inverter. But actually an 800 watt inverter probably would not be enough. This somewhat depends on the appliance, but some things have a start up surge that requires more. This is typically things with motors but may be other things too (I live a DC life for the most part so this is not my area of expertise). I'm not sure how much of a start up surge a refrigerator compressor might have, but it's something you'd want to check.

34 watts sounds crazy low to me for a draw. Just for an idea, I did some Googling. They do tend to "hide" the draw specs I see. Unless you want to dissect the "annual kwh" figures. This is opposite to DC refrigerators where amp draw is right at the top of everyone's list and they show it clearly.

But a general query came up with a figure of from 500-700 watts. So let's take 600. That would be about 5-1/2 amps AC or 50 amps DC (per hour; ouch - my refrigerator draws less than 4 amps DC per hour). So you can see that this "average" household refrigerator would not run on a 300 watt inverter. Of course I'm sure you can find one that draws less (as Scott surely has). But none are going to draw 34 watts (I wish!).

The reason that 50 amps DC figure is important is because ultimately, you ARE going to be drawing DC amps for any appliance you are running via inverter. Because that's where the inverter gets its power - in DC amps from your battery. And, anything you take out you have to be able to put back (always the kicker).

With my 200 watts out in good sunlight and angled for best gain, I can take in up to 60 amp hours in a day (it's hard to know the absolute max, because they will only take in what the batteries need, but I have seen 59-60 amps on a couple of days where I had good sun right after some cloudy days. That's probably a reasonable maximum to expect from 200 watts. In comparison, flat panels won't be able to do as well unless it is mid-summer.

You're going to love solar, I bet. Silent power!

BG

PS: Just for comparison, I'm using an average of around 25 amp hours per 24 hour day to power my small DC compressor refrigerator (cooler shaped). The "real" refrigerator I plan to install has the same compressor, but is larger (4.7 cu. ft). However I don't expect that to draw much more, if any, because it will be much better insulated. I will use a bit more than that in mid-summer, because it runs more when it is hot, but then the sun is higher and better for solar gain then.

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Last edited by Blue~Go on January 31st, 2017, 2:24 pm, edited 1 time in total.

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 Post subject: Re: 110 Volt Fridge
PostPosted: January 31st, 2017, 12:22 pm 
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Posts: 234
Location: Santa Cruz
Hey Paul - My guess is that a 350w inverter will not supply the power needed to start up a residential fridge, but I can't say for sure. In general, a larger inverter will have greater total conversion losses, but that's not always the case; build quality and efficiency (and price) naturally vary. My inverter selection process was pretty simple; it needed to be pure sine, have a remote on/off switch, and have good ratings. I think I paid $150. My setup has inefficiencies for sure (inverter, PWM controller, fixed panels, etc.). But my drop line is large gage and short (14ft), my inverter and controller are inches away from the bank, and I insulated wherever I could. I'll happily tolerate inefficiencies as long as my basic needs are met. We're pretty frugal, though. In all honesty, the whole system was an experiment, yet it needed to be dead reliable since I installed it just before leaving for a half-year North American tour. I'm guessing the fridge is 99% of my power consumption, with the balance being the water pump and LED lights. The fridge I selected is nothing special. I wanted manual defrost (or none), Energy Star rating, and workable dimensions. Low price and availability at a national chain store were windfalls. I don't know what it draws; I guess I should get around to installing my shunt and find out. As Blue mentioned, I had to add a door latch and adjustable bars in front of the shelves to prevent food explosions when autocrossing or rockcrawling lol. I was able to get the stock Premier's Norcold out through the passenger door in one piece (not easy, lots of cursing), and the new fridge slid in right through the back door. The external dimensions of the compressor fridge are much smaller even though the internal capacity is the same as the Norcold (the absorption apparatus and chimney are volumetrically quite consumptive). This afforded me 3.15 cubic feet of new storage space below the fridge in the dimensionally-stock cabinetry, even with several inches of venting clearance all around the fridge. With some creative carpentry, I could get even more. The mounting process was a bit involved and required some notable modifications to the cabinetry, which will probably be your biggest hurdle when changing to a compressor fridge, especially a residential type. Also, there is a wee bit of compressor noise, and a very tiny bit of heat that enters the coach, but all said, it's a far superior alternative to the Norcold for our camping style. I would really love a marine DC unit, but the fridge alone would have cost almost as much as my entire system (and had a multi-week lead time), so I wanted to first try a residential fridge to see if it would work for us. As far as sun exposure goes, I only ran into shortages during extended periods of rain, and I'd usually leave at that point. The 233 AH flooded golf batteries were $300 for the pair, so although I do everything I can to keep them happy, I don't fret too much unless I get down to about 50%. This has happened two times during the course of over 200 days of camping. Both times I just turned off the fridge, cooked up the perishables, and turned it back on the next day. No biggie. Tim - the batteries are in the generator bay. I never had a battery tray, as the stock house battery was under the hood. My fingers are tired. Hope this helps.

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 Post subject: Re: 110 Volt Fridge
PostPosted: January 31st, 2017, 2:39 pm 
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Scott,

Interesting to hear more details on your setup. I like your combination of engineering-mindset plus out-of-box thinking. It looks like we both have setups that work, and interestingly they are coming from somewhat opposite angles.

(In other words, for me the Chinook is my primary thing, so I went with the "proper" marine style electrical setup and a marine type DC compressor refrigerator. Not cheap, but it's what I know (from the past), it works well and since I'm not also maintaining a house, a good choice for me. You went for a readily available no-sweat (but still safe) setup and that sounds like it worked well too. Plus an experiment is always fun. So they are both a win, but in different ways.)

Main thing is that any setup has to "pencil out" in terms of power used, the ability to provide that power -- and the ability to put it back. Without those things satisfied, a system will be annoying and shorter lived.

*******

Interesting about your taking the refrigerator out the passenger door. I had the somewhat larger two-door Dometic that came in the Concourse of my era (and later ones). No way would it go out the back door. I think it would have gone out the window (with window removed) and maybe the passenger door with the Ford door removed (because it doesn't open all that far otherwise). However, I didn't try because I already knew the new refrigerator (Vitrifrigo C130 L) would fit in through the back door by just removing the refrigerator door (simple job).

So I was very undermotivated to possibly cause some damage to the rig, and/or have to remove a window, just to remove an old refrigerator that I didn't want anymore. Hence, I pulled the Dometic out about 12" (leaving the rest in the hole which also avoided interference with the "ell" of the sink counter in the Concourse) and then used a Sawzall to cut all the way around (easy as it's just foam and thin plastic and aluminum there). Hence I ended up with a slim front half and a slim back half which easily went out through the door. All of the possibly gooey/electrical/hydrogen/whatever bits stay on the back half so nothing scary has to be sawed through.

But yeah, figuring out how one is going to remove the old and bring in the new is a good first step!

BTW, I just helped a friend replace a Norcold 2-door absorption (propane) refrigerator (non-Chinook) with a compressor refrigerator. As you noted, without the "chemical fireplace" on the back, the compressor refrigerator is smaller outside for the same given space inside. In his case he got a 25" wide, 20" deep, and 8" high storage compartment for pots and pans, bakeware, etc. I did the opposite and my refrigerator compartment is all the way down (still on top of the generator box) and instead I have a high counter above it (and then a storage cupboard above that that is similar to the other upper cabinets). I wanted a "counter by the door" for various purposes. However my new refrigerator is smaller in capacity to the original (4.7 cu. ft). That's fine for me. I could have fit a large one but wanted the openness and counter space more.

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 Post subject: Re: 110 Volt Fridge
PostPosted: January 31st, 2017, 4:20 pm 
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A few pics from removal of original Dometic RM3663 in my Concourse.

1) Pull out about 12" and apply Sawzall (or equivalent). On this refrigerator the line shown doesn't intersect anything "juicy."

Attachment:
Pull out partway and Sawzall.jpg
Pull out partway and Sawzall.jpg [ 125.85 KiB | Viewed 685 times ]


2) Zip, zip!

Attachment:
Zip, zip, zip.jpg
Zip, zip, zip.jpg [ 61.91 KiB | Viewed 685 times ]


3) Easily take your two slim refrigerator halves out the back door :mrgreen:

Attachment:
Easily remove two slim refrigerators via rear door.jpg
Easily remove two slim refrigerators via rear door.jpg [ 135.03 KiB | Viewed 685 times ]


Obviously this only applies if you are not trying to save the refrigerator. Mine was in very good condition, so I did consider less destructive means, but in the end wasn't willing to risk my back, remove a window, and/or scratch up the Chinook in order to save it. (Especially since the new one would easily fit in the back door.)

I did spend 45 minutes or so capping off the gas line (and testing for leaks), removing the screws holding it in place, and removing the shelves and various plastic baskets and such (which are now in another Chinooker's Dometic). But the actual "operation" depicted above probably took less than 30 minutes.

The carcass was hauled away by someone from Craigslist who wanted to tape it back together and use it at a cabin (or something like that).

I got the idea to cut it in half from reading a truck camper forum -- they have similarly constricted rear doors so can be a source of good tips.

Edited to add: I think I just remembered that pdemarest might have a side door model? Or am I thinking of someone else.... Of course even then the door might not be generously wide.

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