NEW 12 volt full size Refrigerators.

[bradfordwhite]

Wondering if others have discovered or are using the new 12 volt Full Size refrigerators that the RV industry is apparently now using as standard equipment.

 

It has much larger uses than just an RV because anyone can buy them and use them anywhere they want just like any other refrigerator.

 

Since they are 12 volt one can easily power them with a basic 12 volt solar panel and battery system and never have to worry about power outages.

 

When you add in the shift to low draw LED lights and all the computers and phones that run off 12 volt DC. it's just incredible how quickly one can shift to not having to be connected to the electric grid.

 

The old RV frigs were bad.  You had to have two gapping holes through the walls so they could vent outside which means you can't move them, they were slow to cool, they were toxic because of the gases used in them, and they weren't that spacious.   Also they weren't efficient and have been the cause of many RV fires.

 

The new ones are 12 volt only and efficient low draw at that.  

 

Incredible.  So impressive.

 

 







 

https://www.rvupgradestore.com/Gene...MI0_zxspXw-AIVCMqUCR2YSQYaEAQYAiABEgKRafD_BwE

 

[Chetlaham]

I love this, thank you!

I have always fantasized about having solar panels on the roof, deep cycle batteries in the basement, analog voltage indicator in the kitchen and 12 volt receptacles (and lighting) through out the home. With a service company that can replace/maintain the batteries and panels if any show up bad over time.

 

[cfz2882]

Probably a BLDC hermetic compressor in that fridge-seen a few 12 and 24v BLDC hermetics last 7-8 years-even automotive AC compressors.Similar to a "inverter" mini-split BLDC compressor,only low volt DC.Chetlatham,I have such a 12v system running in one backyard building-just for kicks-bank of deep cycle batts charged by PV panels and small wind turbines that I enjoy goofing with

 

[circlew]

Keep in mind that the lower the voltage, the higher the amperage. For example, 200 watts at 12 volts is over 16 amps, which requires #12 wire. This means much heavier gauge wiring is required. Even the old 32 volt farm lighting generator - battery systems required much heavier wiring than a 120 volt system. This increases material and labor costs drastically. Very impractical for building wiring.

 

[cfz2882]

12v voltage drop

yep,i have used quite a bit of # 12,10,8,6 wire in the setup to reduce the voltage drop problem with 12v-I have a lot of salvaged wiring,so no expense mostly 21 watt automotive/RV bulbs,a few Edison base 12v 50w bulbs,some MR16 35 &50w,and LEDS.The old 1980 vintage transistor driven Tripp lite inverter does pull a little current...

 

[bradfordwhite]

It's true that DC does not travel well over long distance wires. That's why years ago, when electric was first discovered they switched to AC because it could be created at a single generating station and then sent out to numerous places miles away.

When you're making your own power at home, on your roof or in your yard you aren't worried about all that non-sense. Most RVs trailers, motorhomes, even automobiles use 12 volt DC lighting and appliances and they are often wired with 14 & 12 gauge stranded copper.

Home wiring for standard circuits is typically done with 14 and 12 gauge solid copper, though you can use stranded as well.

Think of how much HEAVY gauge copper and aluminum wire is out there strung along the roads and buried under ground to keep alive the central generation plan for electricity from years ago. The tree trimming and pole maintenance that must be done yearly to keep those lines active.

Think of how nice it would be not to ever have to worry about power outages and electric bills.

Home wiring is a one time expense.

 

[gizmo]

solar and refrigeration

I have lived on solar off-grid for over 20 years. We have a 24 volt DC battery system, 3000 watt 24DC to 240AC inverter that can do 5000 watts for half an hour; 3.6 kW of PV panels  (soon to be 4 kW when I put up the last 2 panels...).

We have a standard 240 volt 2 door fridge. The 12 volt fridges generally aren't worth the bother in permanently occupied homes. There are clear reasons for this...

RV fridges have to work under much harsher conditions than domestic fridges - vibration, poor ventilation, very high ambient temperatures. Also space is at a premium inside RVs, so RV fridges often have thin insulation that costs efficiency.

I have seen many, many DC fridges advertised and most of them are less efficient than a standard 240 volt fridge sold here. This is mainly because of thin insulation and they have to run at high condenser temperatures / low evaporator temperatures due to the hostile environments they need to function in. This makes them use more power for a given amount of cooling. I have seen similar-size DC fridges to mine, advertising as a feature that they use less than 1 kW/h a day. My 240 volt Chinese cheapy uses half a kW/h a day.

 

Some DC fridges are standard fridges with compressor conversions, these are more likely to work well in a solar home, but they are super expensive.

SunFrost used to make special super-insulated fridges in the USA, not sure if they are still around. They were HUGE due to thick wall insulation and astonishingly expensive.

 

Solar is cheap now. It is revolutionary. You don't need special fridges, though you might choose a smaller one than the average US fridge. Compare prices between a 12 V DC home-size fridge and its standard (110V or 240V) equivalent. The DC one is so much extra, you would be better buying a very efficient "normal" fridge, and using the difference to fund a couple of extra solar panels in your array and you'd still have change in your pocket. Also you will have a "normal" fridge with spare parts easily available and able to be repaired by your local appliance tech.

 

When we built this house, which was designed to be future-proof and super efficient, we installed a gas line to the fridge cavity as we had a small LPG RV fridge. No longer used, the gas line for the fridge is capped off. We also added, at great expense, a dedicated 24 Volt DC cable from the battery shed, through underground conduit, to the fridge cavity in the kitchen. We were planning to buy one of the "high efficiency" DC fridge conversions, at over AU $2000. The DC line has never been used. We now have a 220 litre Oracle fridge, made by Haier, it cost us AU $298 brand new. Same as this one... https://www.gumtree.com.au/s-ad/ber...igerator-oracle-model-no-octm217wh/1297927926  It works fine, uses hardly any power. It's a standard 240 volt fridge, perfect for us. And newer ones are even more efficient. It runs off a "normal" Australian 240 Volt power outlet. It uses less than 500W/h a day.

 

[gizmo]

expired link

Sorry the link I posted to yesterday has expired already - it must have sold.

Anyway, basic 217 litre white 2 door, freezer on top, fridge.

Now we can buy 400 litre fridges that use less power than my Chinese 217 litre one.

Refrigeration technology is still getting more efficient at quite a pace.

 

[kb0nes]

So do we know if this unit actually has a 12v compressor or just has an internal inverter? Somehow I would assume the latter is more likely than having a 12v compressor.

With inverter technology today I really don't see this as much of an advantage. Why not just choose a 120v AC fridge and buy an inverter then you can run any other 120v AC loads too? I would feel compromised being stuck with 12v distribution only. With LiFePo4 batteries, low cost solar PV panels and MPPT controller/inverters alternative energy is getting affordable, reliable and decently efficient. I just bought my first LiFePo battery a couple months ago and it is an impressive bit of kit after years of dealing with lead acid non-sense ugg.

As for power distribution, DC travels just as well as AC, it is the voltage that is the issue. Since DC doesn't allow for easy voltage step up/step down it lost the battle early on. Choosing 12v for the power system is a big mistake, one would do much better at 24 or 48v to improve efficiency and reduce wiring sizes.

 

[henene4]

There are certain fridges that warn against running them on inverter power supplies.
More so especially those that do have inverter compressors.

It's kinda like how you can only run certain LED bulbs on dimmers.
No matter how good an inverter is, "true sine wave" isn't the same as the sine wave from the grid.
You can get VERY close - enough to feed into the grid - but especially cheaper equipment might not get there.
And with the high performance inverter drives for compressors that "dirty power" can lead to a lot of issues.

If a fridge runs of 12V DC it HAS to have an inverter.
DC motors have to be actively commutated - either via a drive system or via brushes, and brushes just can't be made to work in an refrigeration compressor application.

And once you go to a drive system you will probably just aswell integrate a voltage shifting step.
Not quite that easy, but frequency is speed of the compressor, and voltage is power/torque, so high voltage helps on startup.
You could probably make that work without voltage shifting by very slow ramp up of frequency, but why make it harder than it needs to be?

Once you go to the scale where most solar installations run and with the fact that most solar installations do want to feed into the power grid running fridges off of such high quality inverters won't be a problem no matter the kind of fridge.

But on such a small installation like an RV, you might run into trouble, so the fridge going around that hurdle makes things just easier.

Side note on that:

Had it a few times happen to me that touchscreen devices behave erratically while plugged in on trains.
Actually happened to me here in Europe and when I visited China.
Inputs would register incorrect or the device would have phantom inputs.
Once unplugged they ran again no problem.

That electrical noise from the inverter shifting the usually lower frequency of the train power lines to the usual 50Hz for the plugs behaves like electromagnetic interference and even makes it through the well filtered switch mode power supplies for high tech gadgets.

Same principle applies to lower spec DC/AC inverters.

 

[kb0nes]

A refrigerator today, even an inverter model will run just fine on pretty much any modern inverter of decent quality.

Even my decade old Honda inverter generator has a remarkably clean output, I have monitored it both with my oscilloscope and a spectrum analyzer. Yes there is some RF that remains, but I have yet to find any device that didn't run perfectly on it. Only exception is hearing a few birdies on sensitive HF receivers.

Any disclaimer is pertaining to old inverters that were indeed pretty crude. Using the example of an LED run on a phase angle dimmer is entirely a different issue.

 

[bradfordwhite]

12 vlt compressor. That's one reason it's so efficient. Nothing is lost to conversion.

 

[henene4]

As I said, it physically can't be run directly off of DC.

And a dimmer switch is remotely a good comparison.

All it does it switch off and on at certain points of the sine wave.
Any dynamic system will then buffer the sudden switches (for example a hot filament needing time to cool down).

An electronic system with very little dynamic properties will experience the fluctuations.

An inverter does switching with not all to dissimilar components - just way more sophisticated AND usually with lots of smoothing to mimic the typical supply voltage from the mains.

 

[bradfordwhite]

#9

Henrik, I want to check with the manufacturer to make sure.

In the second video he says it's a 12 volt frig with no inverter. He also talked about how efficient it is compared to a standard 120 frig with an inverter and also a typical RV frig using a 12 volt heat source to power the chemical reaction. This 12 volt frig is super efficient compared to the 3rd one.

 

[gizmo]

super efficient compared to the 3rd one.

The third one is an absorption fridge, made as a gas fridge but it can be fitted with an electric element. They are horribly inefficient. They will use something like fifteen times more power for the same refrigeration, compared to a compressor fridge.  I recently helped a friend of mine swap a 45 litre gas fridge in her campervan to a Dometic brand 12 volt Dc fridge of 80 litres. (Needed some cabinet work to fit the larger fridge.) It uses dramatically less power - she says she no longer has to connect to main power to recharge, the single 240 watt solar panel on the roof meets her total needs (just fridge and lights.) In an RV this is a great solution, but in a solar powered home the sums don't add up. Cheaper to get more solar panels, a standard fridge (still choose a very efficient one, the difference between models is amazing). Every true solar powered home will already have an inverter these days, or at least those without one would be extremely unusual.

 

"12 volt fridge with no inverter" - Henrik is right, it WILL have some sort of inverter. Understand though, the word "inverter" can be understood 2 ways: A DC:AC conversion device to allow normal AC household appliances to run off a DC battery, like my house runs off - no, it doesn't have that. But any device that calls itself "brushless DC motor" is in fact some sort of AC motor, possibly single phase, possibly three phase, that runs off a dedicated power supply that converts the DC input to a suitable AC wave form for the motor. ALL brushless DC, hermeticaly sealed DC refrigeration compressors work this way. They ALL have a small black box that takes in DC and converts that to some type of AC to the compressor - it may not be 110V AC, in fact they often use quite sophisticated variable voltage, variable frequency drives that adjust motor speed to suit heat loads and ambient conditions. The black boxes all contain some sort of inverter technology, whether the importer/distributor understands that or not.

 

There used to be genuine DC motor refrigeration compressors, Indel of Italy made them for one. They used a brushed motor and ran on 12 volts DC. They were not hermetic (the motor wasn't sealed inside a black metal casing) but had a shaft seal to hold the refrigerant inside with an external DC motor. You can't put a true DC motor inside a hermetic compressor, as sparking affects the refrigerant gas. These Indel compressors were sold in USA in the 1980s/1990s, in a refrigeration kit for boats or RVs, Sears sold them as I recall. They were sold here in Australia in a camping fridge called "The Ridgy-Didge Fridge." (Ridgy-didge is old Australian slang meaning "true or genuine.") They were very unreliable, the seals wore out and they lost the refrigerant gas.

 

Trust me, I've been there. I originally wanted, and started to create, a home that ran without an inverter on 12 volts or 24 volts DC. Then solar panels plunged in price, inverters became cheaper, more reliable and more efficient, and "normal" appliances became more efficient due to those government-driven efficiency schemes that people moan about. Best option is an efficient inverter, standard appliances (choose highly efficient ones, though) and pocket the savings. You can of course convert appliances to run on DC (I did several washing machines, made a few DCC converters to run gadgets that would normally have a wall wart plug, like cordless phone; had a DC water pump on water tanks, and so on.) I spent money and time on the conversions, but have mostly given up on that and gone "conventional." I do still have DC wiring in the house though - two lights and five power outlets are 12 volt DC, they are fed off a 24:12 volt DCC converter. So if the inverter fails we will still have very basic power supply.

 

[bradfordwhite]

My issues are that it:

runs off 12 vt
It runs efficiently
it's a spacious frig
it doesn't require special venting
it's a compressor based cooling system.
it cools quickly
it doesn't have inordinate and dangerous gases like amonia.

Interesting experiment someone did:

 

[gizmo]

Yeah, nothing magical happening there. They are using an... inverter.

 

The voice-over guy says you run the fridge an hour from the battery, via the inverter - then you recharge the battery for an hour as the battery will be discharged. HOW? The whole point of the "experiment" was how to run a fridge off a battery when the mains power has failed. Well for an hour, OK. But for several days of power failure, you need a DC supply to recharge (eg solar), and big enough battery to run the fridge overnight without charging.

 

What they did in that video is a miniaturized version of how my whole house has run since it was built. Solar panels charge the batteries, inverter converts the DC in the batteries to AC for the house. My battery bank is very roughly 1.8 metres wide, one metre deep and 750 mm high. (six feet wide, three feet deep and eighteen inches high.)

 

[bradfordwhite]

gizmo, what kind of batteries do you have?

I've dug out my solar panels and custom made charge controller that I had in storage since 2014 and am going to set it up again. Back then I had standard lead-acid.
Now they are saying Lithium is a much better way to go as it discharges evenly and doesn't need venting (though they need to stay cool).

There have been tests run with these new 12 volt refrigs, as was shown above. They are incredibly efficient. It's so promising.

Taking it a step further...if they have the tech to do a compressor refrigerator at 12 volt, they would naturally be able to do compressor air conditioning at 12volt.

 

[bradfordwhite]

I only have 140 watts on two mono-crystalline panels and my charge controller housed in a previous home security system cabinet.

 

[cfz2882]

12v A/C is here today.

is made for automotive applications-modern BLDC motors benefit from better drive transistors than was avalible in the past.I am reworking(mostly just tidying up)my backyard 12v off grid setup now-4 small wind turbines and 100w PV panel(made in Canada in 2002,but just recently deployed after long storage)Plan to add 2nd 100w Canadian panel and possibly a big,~175w Samsung panel-that one is meant for 24v,so may carefully dig into it and reconnect the cells for 12v use.

 

[eronie]

All high end Tesla cars have DC heat pump compressors.

 

[gizmo]

may carefully dig into it and reconnect cells for 12v use

OH FFS NO, don't do that. You will wreck the panel.

 

Get an MPPT charge controller. They allow the panel voltage to be way above the battery voltage, they are much more efficient any way. Depending on the model, they could charge a 12 volt battery from up to 80, 120 or even 150 volts panel array, though they are most efficient when panel array nominal voltage is roughly double the battery voltage.

 

100w panels are so small they are barely worth the effort and hardware to install them  these days. I don't know the situation in the USA, but here you can get second hand solar panels for almost scrap value very easily. They are all over Gumtree for example. My last collection was 8 x 200 watt Trina panels for (from memory) AU$200 the lot including the mounting frames and clamps. That's 1600 watts of panels for about USD$135. They had been removed because the home owner was upgrading from a 1600 watt system to a 6600 watt installation. People want the cells on the roof to all match these days to look nice, so they don't add to existing systems, they replace small systems with big systems. If you are prepared to go out and collect used decommissioned panels, they are absolute bargains.

 

I digress - MPPT regulators allow you to have a 24 volt panel system charging a 12 volt battery. The internal electronics match up the voltages. That's similar to what I have - 3600 watts of PV panels, nominally they are pairs of 24 volt panels in series, so nominally a 48 volt PV array charging a 24 volt bank of batteries through two MPPT regulators, an older Apollo Solar 80 amp regulator and the newer addition, a Victron 70 amp Blue Smart regulator.

There are cheaper ones around, I believe Renogy and Epever are good quality cheap brands of MPPT regulator.

I say "nominally" because in good sun, panel voltages run way higher than the rated voltage - My "48 volt" arrays run at 65 to 75 volts in good sun, the MPPT regulators allow the panel voltage to go that high for better efficiency.

 

My batteries are getting on now, they were new in 2006. They are Exide Energystore 2 volt 1330 Amp/Hour lead-acid cells, a bank of 12 cells to make a 24 volt system. I look after them well and they still perform like new as far as I can tell. They do need to have distilled water topped up every month, but I have a home distiller I bought on Ebay so I brew my own distilled water using surplus power on sunny days and stock it up over summer. I distill rainwater so it's all free. I very rarely let them get below 90% charge, they have NEVER been below 85% charged. That's right, lead acid cells should only operate on the top 10% charge to get a good long life. So a 200 amp/hour battery should never have more than 20 amp/hours taken out. The lower you discharge them, the shorter the life and it gets dramatic below about 60%. My first set were 15 years old when I got them and we got another 15 years, 30 years is a great life but they were pampered. My current ones were bought new in 2006, I hope to get 20 to 25 years from them. Then I will compare lithium and lead acid, plus any other technologies that may be around by then.

 

I suggest you watch some Youtubes on solar MPPT regulators. Will Prowse has some good ones, he has made an absolute fortune as an online solar guru. He expresses himself clearly and gets his point across well.

 

He is absolutely gorgeous, so that is a bonus, too.

 

[cfz2882]

Ya,thanks for the suggestion on using the 24v panel with MPPT controller -control for one of my larger wind chargers is MPPT and has PV input terminals-presuming the PV input is also MPPT There are quite a few used panels avalible,but they are far from me and " local pickup only"My setup is quite small,so 100w is useful-gets about 6a charge BTW,for others reading this,MPPT:maximum power point tracking

 

[bradfordwhite]

I don't think "digging into" a solar panel to reconfigure the leads is a good idea. They are sealed to protect them from moisture and it would be a lot of tedious work.
Best to sell that panel and get 12 volt. They are so inexpensive these days.

The panels I have I bought new back in 2013 and was thrilled because the prices had dropped so much. Well, they've continued to drop. Even Pure Sine inverters. Back then I think a quality 2500 watt/5000 watt was upwards of $300+. Now you can get it for about half that.

 

[gizmo]

Best to sell that panel and get 12 volt.

Bad advice! Get an MPPT regulator, then that panel will work perfectly. BETTER than a 12 volt panel. There are advantages in having panel voltage about double the battery voltage, but this requires an MPPT regulator. You will get better performance at beginning and end of the day, when the sun is at a poor angle to the panels; you will get better performance in cloudy/dull conditions.

I live in an area with lots of cloudy weather, and our system performance dramatically increased when we changed old PWM regulators to MPPT and re-configured the panels to series strings of 48 volts. (2 x 24V panels in series.)

 

Use a regulator like this: https://www.amazon.com/EPEVER-Contr...ppt+solar+regulator+epeve,aps,332&sr=8-5&th=1

 

Or this:

https://renogy.com/rover-elite-20a-mppt-solar-charge-controller/
The
Renogy is often cheaper on Amazon, but currently showing out of stock there.

 

Renogy also have an excellent state-of-charge monitoring system for a good price:

https://renogy.com/500a-battery-monitor-with-shunt/
 

I have installed a couple of those battery monitors for friends, they are great. They tell you a % state of charge, instead of trying to guess it from battery voltage, which is hopelessly inaccurate.

 

[cfz2882]

12v compressors

looking at what is avalible from the usual retail sources,looks like most are cast aluminum,bolt together,BLDC motor with separate driver,and by the low prices of many of them,probably made in China. Also the pump is scroll type on some I looked at specs on. Seen some in kits of associated parts for under 300$ to some over 1600$ for just the compressor.