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12v or 12ov fridge

L

littleboss

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Joined
Feb 25, 2022
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9
We are building a toy hauler. Was looking at 12v fridges. They are very expensive. Cheapest is a Dometic 12V is about $1000. Rated at 156W.

I can buy a 120VAC fridge for $400. Draws 15A. So would need a 3000W inverter to be safe.

Am I better off buying the 12V fridge, and using a 2000W inverter or going with the 120VAC fridge and use the money that I saved on more solar panels, another battery and the larger inverter

We will probably be using the toy hauler less than 3 weeks a year
 
From experience I can state that a nice size 12 VDC model pulls @7amps when running, of course it doesn't run full time. That load is easy to manage when some solar a Lifep04 battery.
 
I would probably convert a tiny chest freezer with a fridge temp controller and get a Phoenix 1200w/12v Victron inverter.

You could also just use the chest freezer as is to make ice and keep coolers going. You could keep ice cream too!
 
dktool said:
a nice size 12 VDC model pulls @7amps when running,
Click to expand...
84W seems very good. Link? I'm also curious as to how "nice size" relates to "fun size".

I have to say i really liked my propane fridge (also 120Vac). It ran a long time with minimal propane consumption. An excellent choice for low sun areas or if you don't have a huge battery/solar/alternator/shore power solution.
My new RV has a 12V fridge 8cuft, it uses about 55W and runs about 50% duty cycle when very hot outside. Need more data points (need to get it out of driveway a lot more).
 
Decision depends on whether or not you are gonna have the 2kW inverter in any case.

My ancient (20 years old) nuthin' special non-inverter Fridgidaire 7.5 c/f top mount needs 115W, like TM48's. Duty cycle of apx. 30% in winter, with ambient around 65 - 70, 50% in summer when we let the house temp rise to 78-80.

Newer inverter style fridges are supposed to be even more efficient. With one of those, you may be within only a few watts difference btwn. a DC and AC fridge of the same size.

Of course, there will be some conversion loss in your inverter, but if you choose carefully you can get that to under 10W.

I wouldn't mess around with DC. There are a whole lot more choices when you buy AC versions and as already stated DC fridges are usually at least twice as expensive.

If you are living off-grid, that's a whole different ballgame, and ultra-efficiency matters. The "convert a chest freezer" is the way to go if your solar system is small, but chest freezers are a PITA to dig around in looking for the item you want.
 
My side by side French door fridge (36" wide) uses 1.5kWh a day. That's with 3 people using it. The official draw of a certain current occurs only a small part of the time.
Note that upon compressor start, there's a surge.
 
MisterSandals said:
84W seems very good. Link? I'm also curious as to how "nice size" relates to "fun size".

I have to say i really liked my propane fridge (also 120Vac). It ran a long time with minimal propane consumption. An excellent choice for low sun areas or if you don't have a huge battery/solar/alternator/shore power solution.
My new RV has a 12V fridge 8cuft, it uses about 55W and runs about 50% duty cycle when very hot outside. Need more data points (need to get it out of driveway a lot more).
Click to expand...
Dometic 10 cubic foot https://www.dometic.com/en-us/outdo...ators/dometic-dmc4101-12v-refrigerator-242459
 
JC Refrigeration units

Dutchaire Refrigerators Archives - JC Refrigeration

Since 1994 JC Refrigeration has been manufacturing absorption style refrigerators. So, we have many years of experience and you can be assured that all of our cooling units are quality built and individually tested before they are sent to our customers.
jc-refrigeration.com jc-refrigeration.com
 
littleboss said:
Am I better off buying the 12V fridge, and using a 2000W inverter or going with the 120VAC fridge and use the money that I saved on more solar panels, another battery and the larger inverter.
Click to expand...
I've found the 12v fridges to be less reliable and most of them aren't self defrosting which means they turn into mold factories in many climates. YMMV

I'd stick with the most reasonably priced energy star rated 120v fridge I could source locally.
 
OzSolar said:
I've found the 12v fridges to be less reliable and most of them aren't self defrosting which means they turn into mold factories in many climates. YMMV

I'd stick with the most reasonably priced energy star rated 120v fridge I could source locally.
Click to expand...
I have a friend with a 12v/24v fridge and yea, its buggy. It just stops working from time to time. I wonder how many of these issues are the 3 phase driver vs the actual compressor. They have mold issues but I have a 120v self defrost unit and have had zero issues in the same humid climate. I wonder how many of these issues with mold are with temperature climbing to high on the DC units.
 
A fridge is about 100-200w when running. But when the compressor starts it can peak to 15A at 120v. A 12v fridge can compensate for this with a big capacitor which increases power factor.

So the biggest problem with being off grid is that just leaving the inverter on so that devices can draw power when needed, wastes so much power. I lose about 100w per hour with my setup. I could be charging a nintendo switch or something low power and its going to drain 100w per hour no matter what. If you have a lot of devices and a large system and not many cloudy days, its fine.

If you can keep everything 12v, you save soooo much power. You can keep your system smaller. My system has dedicated 12v outputs, so my internet runs on 12v and that will last for a week or more without charging. But if you have 1 have to have device thats 120v that switches on and off all day, you have to beef up your system to keep that inverter on.

So i would say, if you only need 120v to watch tv for a few hours or run a microwave, and you are ok switching the inverter off and on when you need it, you will save power and reduce the amount of gear you need to obtain and store all that power that gets wasted. And reduce maintenance on that gear.

If you have to have 120v all the time, you have to do what you have to do.
 
littleboss said:
We are building a toy hauler. Was looking at 12v fridges. They are very expensive. Cheapest is a Dometic 12V is about $1000. Rated at 156W.

I can buy a 120VAC fridge for $400. Draws 15A. So would need a 3000W inverter to be safe.
Click to expand...

15A seems awfully high. Link the fridge.

If you are building a toy hauler, the choice is simple. Get a Dometic chest fridge/freezer. or something like the Iceco. I have a CFX95 in the the back seat area of my pickup and have 12V power run from the camper solar system. Larger freezer compartment and when open cold air isn't lost. 38W when running.

littleboss said:
Am I better off buying the 12V fridge, and using a 2000W inverter or going with the 120VAC fridge and use the money that I saved on more solar panels, another battery and the larger inverter
Click to expand...

I want to replace the 3 way in the truck camper with a new fridge just for convenience. We currently don't use it as we use the Dometic CFX for our current needs but when you want something from the fridge, we have to exit the camper and go to the truck cab. I have looked at DC fridges in the past but have been considering an AC fridge with a small inverter instead. We don't run the 3Kw Growatt unless we need AC power.

So like you I'm still looking for the best solution.


littleboss said:
We will probably be using the toy hauler less than 3 weeks a year
Click to expand...
Here is one thread to read.

DPC

Thread 'Best off grid fridge suggestion'

Im shopping

Looking at a few fridges and options.
I think its more cost effective at this point to stick with an AC fridge and put more money into extra generation capacity than go with a DC fridge.
I am thinking about a 10 cubic foot Direct cool conventional compressor unit.

What are you guys thinking?
  • Like
 
eppich8479 said:
A fridge is about 100-200w when running. But when the compressor starts it can peak to 15A at 120v. A 12v fridge can compensate for this with a big capacitor which increases power factor.

If you can keep everything 12v, you save soooo much power.
Click to expand...
Every 12v compressor I have seen on the market is a brushless 3 phase DC motor, no start capacitor. There would be no start surge which is very nice. That would be for an inductive AC motor.

With a very efficient inverter and a 120v conversion style(not frost free / 1200w heat element) fridge/freezer, power saving would be minimum vs 12v DC (which will also have some driver losses)

While frost free fridges have a heating element to defrost the evap coils, some fridges have a second heater between the freezer and fridge door on the outer surface skin.. FYI
 
eppich8479 said:
A fridge is about 100-200w when running. But when the compressor starts it can peak to 15A at 120v. A 12v fridge can compensate for this with a big capacitor which increases power factor.

So the biggest problem with being off grid is that just leaving the inverter on so that devices can draw power when needed, wastes so much power. I lose about 100w per hour with my setup. I could be charging a nintendo switch or something low power and its going to drain 100w per hour no matter what. If you have a lot of devices and a large system and not many cloudy days, its fine.

If you can keep everything 12v, you save soooo much power. You can keep your system smaller. My system has dedicated 12v outputs, so my internet runs on 12v and that will last for a week or more without charging. But if you have 1 have to have device thats 120v that switches on and off all day, you have to beef up your system to keep that inverter on.

So i would say, if you only need 120v to watch tv for a few hours or run a microwave, and you are ok switching the inverter off and on when you need it, you will save power and reduce the amount of gear you need to obtain and store all that power that gets wasted. And reduce maintenance on that gear.

If you have to have 120v all the time, you have to do what you have to do.
Click to expand...

Current crop of stand-alone HF inverters draw < 10W no load. I have two that do.

If you have shackled yourself to an AIO, well, we all know how bad those are...
 
Couple years ago, one of my "shop neighbors" put a Haier 2.7 c/f mini-fridge out next to the communal dumpster for disposal. I figured it either a: doesn't work, or b: had something spill inside that was so skanky they had to get rid of it.

Neither was the case.

It ran, cooled quickly, cleaned up well, and other than some exterior scratches and dings, works fine.

Anyway, I re-purposed it as my mobile "ice chest". It needs a 1kW MSW inverter to start up, but quickly settles down to 55W run. On an average day, with temps around 70 - 80, duty cycle is about 40% for an interior temp of 38 - 42.

When on a road trip or camping, I have a used Trina 250W panel (SanTan), an EPEVER CC, and a LiTime 12V / 100aH LFP to provide power.

With that setup, and the Haier on 24 / 7, I hit Float on sunny days btwn. 1100 - 1300.

It is extremely nice to have this instead of my very old Igloo peltier effect cooler. It actually uses far less power since it cycles off and on and you can make ice for margaritas (yep, I have my priorities).

When I go to town for supplies when I'm at my remote place, it's very nice to be able to buy frozen foods and bring them back to stuff in the Norcold in the trailer.

Anyway, I toss this "use-case" out there for those that advocate that DC is the only way to go.

Attached images are "breakfast on the road" near Bluff, UT when the Haier is in the Transit Connect, the other is when we are camped out using my 3/4 ton Chevy K2500 with work shell (fridge is on the left, just inside). When I am mobile, the Haier gets secured to the shelving with a ratchet strap around the middle to keep it from walking around.
 

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I do have an AIO. If i go whole home solar it wont be all in one. If there are better inverters, then make sure you get one. I think the 12v fridge he is asking about is equal powered to a normal small fridge in performance. It could easily step up voltage for whatever motor. Its only 1/4 HP usually. 120v @ 1A is still 120w just like 12v @ 10A is 120w
 
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