A lot has been said about Inverter inefficiency, but I don’t worry about that as I have a fridge that works beautifully in temperatures of 42c in summer and it can handle the off road conditions as our van in the image is fully off road and the fridge has done many thousands of kilometres of corrugated roads and not missing a beat. May plug into mains about every 3 months or so for a short time. Have plenty of solar on roof and 400ah of lithium battery storage. Would I go back to using a 12v fridge, no way. Don’t have generator and don’t charge from alternator, van is purely 12v solar. My earlier post has a little more info.
best fridge set up ?
- Thread starter davehop
- Start date
A way of overcoming inverter inefficiencies was featured in a utube.video by " into the mystery 13" a few years ago..
In this he disconnected the ac power to every thing but the compressor and operating everything else on 12v powered through relays to the inverter on off switch. When the fridge needed to turn on the relay connected to the 12 v switch and it powered up.
I have no idea if this was safe , legal or even worked, I am only delving into my memory bank and Leave it up to the experience of others to comment
Alla
42c! damn that's hot. The concern with inverter inefficiency isn't so much whether it can handle high temperatures and keep a fridge cool, its the extra wasted power that you have to account for. Though the ability to keep frozen things frozen and cold things cold is pretty important too, especially the former.
This is important, other than efficiency, its the other main concern I have with a normal household mini fridge. But if yours can handle 1000's of K's of corrugation, it should handle most anything you come across.
How are you defining/measuring efficiency here? Lower power draw at a given temperature including inverter overhead? Lower power draw of the fridge only? More effective at freezing things? All of the above?
Most proponents of AC fridges don't claim that they are equal or more efficient. The argument is usually that the marginally better efficiency of 12/24v units doesn't justify the added cost. And it is a persuasive argument for many use-cases. But I haven't heard anyone claim their 120/220 AC unit was more efficient (since the fridge itself is DC and requires a conversion from DC (batteries) to AC (inverter to wall plug) and then back to DC (fridge internals) with associated efficiency losses at each conversion poitn, it seems it would be impossible to be more efficient if all other things are equal. Maybe your 220v fridges in Australia are made to a much higher energy efficiency standard than here in the US (I think this is true in the EU) but I still have a hard time believing your 220v unit can be more efficient than a DC fridge in a DC system unless I'm fundamentally misunderstanding something (which is likely ?).
This is probably a big part of the reason you don't care about inverter inefficiency or fridge inefficiency. 400ah is a lot more than most offroad builds have. If a fridge is a small part of your total energy budget saving 10-30% doesn't matter much, if its your main energy consumer and you only have 1200w/hrs as is common in small builds, 10-30% savings can be huge.
I don't understand why having a generator or charging from alternator would affect your decision to go with a 12v fridge or not? regardless of whether you use 12v or 220v your system is 12v, your drawing power from your batteries and charging from the sun. What am I not understanding?
Last edited:
That is really interesting, so if I understand correctly, you would use a dedicated inverter for the fridge that switches on and off as the compressor cycles, and all other components are powered directly by 12/24v.
Its a cool idea, no idea if it would work or be worth the effort. It would prevent the continuous parasitic draw of the inverter running 24/7, it wouldn't do anything for the inverter conversion efficiency though.
Some people have asked if I run a genie or charge batteries from alternator to top up in cloudy conditions. With my setup I have gone for 5 weeks of cloudy conditions and rain and my batteries have not gone below 85%. That’s why I don’t worry about Inverter inefficiency and being a Inverter fridge it doesn’t have a high power draw.
I've never heard of an inverter fridge, looks like I have some research to do, do you have any idea what sort of power it draws on average?
Yeah if I was never dropping below 85% in worst case conditions and all my energy was free solar I wouldnt give a crap about efficiency either.
pat.kane
New Member
It isn't easy to identify inverter fridges in the US via a web search or even on the product pages. Here's a good thread on the topic: https://forum.solar-electric.com/discussion/351398/lg-inverter-refrigerators
The 20cuft LG LTCS20020S is $700 at Home Depot (inverter is shown at the very bottom of the page) and https://www.ajmadison.com/cgi-bin/ajmadison/LTCS20020S.html (inverter is not listed anywhere on the page but is in the PDF spec sheet available on the page).
The 11cuft LG LTNC11131V is $630 at Home Depot (inverter is NOT shown on the page anywhere) and $700 at https://www.ajmadison.com/cgi-bin/ajmadison/LTNC11131V.html (inverter is listed on both the page and spec sheet)
The 20cuft LG LTCS20020S is $700 at Home Depot (inverter is shown at the very bottom of the page) and https://www.ajmadison.com/cgi-bin/ajmadison/LTCS20020S.html (inverter is not listed anywhere on the page but is in the PDF spec sheet available on the page).
The 11cuft LG LTNC11131V is $630 at Home Depot (inverter is NOT shown on the page anywhere) and $700 at https://www.ajmadison.com/cgi-bin/ajmadison/LTNC11131V.html (inverter is listed on both the page and spec sheet)
Darkstar
Rain Wrangler
- Joined
- Dec 31, 2019
- Messages
- 339
Solid info.
Big one uses 439KWH per year
convert to watts per hour avg
439X1000/365/24=50 watts per hour avg
Little one uses
39 watts per hour avg
Check my math?
Last edited:
pat.kane
New Member
@Darkstar the thread I linked to states not to trust the rated energy use. Consumer Reports showed actual was less than other lower-rated fridges, and the guy posting was seeing <30W/hr average for the 20cuft version. He also wrote "actual power used is about a kw a day with the inverter no load loss plus inefficiency"
If true, that's not bad at all. Pretty impressive really. Though I'm hesitant to believe that the manufacturers are overstating the energy consumption, until I find data that shows that, and see what the test conditions were. I would ask for the consumer reports link, but there content is normally behind a paywall.
It would be interesting to see what sort of efficiency could be achieved by combining the inverter fridge tech with the small form factor well insulated 12/24v chest style fridge/freezers.
I came across some 12v fridge test data on another forum, test fridge is a 63qt edgestar (cheapest 12/24/120v chest fridge/freezer) I am posting the link here for reference.
The first tests were tests were done via 120v AC, measured at the plug via a Kill-a-Watt. The ambient temps were a stabilized 68f in the day and 62f in the night. Results were 7% higher than 12v power draw specs without accounting for inverter losses (another 8-20%):
The second test was done via 12v DC, measured with a multimeter, with a stabilized ambient temp of 80f and the fridge set to 30f:
These tests were done by different people, so the results will not be completely comparable but should give a good ballpark indication of what a cheaper 12/24/120v fridge may consume in different real world scenarios. Its also worth noting that the first tester tested the fridge empty, while the second tester doesn't state what was in the fridge but implied that it was tested with thermal mass inside.
The first tests were tests were done via 120v AC, measured at the plug via a Kill-a-Watt. The ambient temps were a stabilized 68f in the day and 62f in the night. Results were 7% higher than 12v power draw specs without accounting for inverter losses (another 8-20%):
The second test was done via 12v DC, measured with a multimeter, with a stabilized ambient temp of 80f and the fridge set to 30f:
These tests were done by different people, so the results will not be completely comparable but should give a good ballpark indication of what a cheaper 12/24/120v fridge may consume in different real world scenarios. Its also worth noting that the first tester tested the fridge empty, while the second tester doesn't state what was in the fridge but implied that it was tested with thermal mass inside.
pat.kane
New Member
I was scratching my head on that as well. I did some googling and bailed midway as it didn't seem like a productive use of time. I was curious if the test protocols didn't really reflect how a fridge would be used and/or weren't technology agnostic. The ENERGY STAR(R) Program Requirements for Residential Refrigerators and Freezers is available online and points to 10 CFR 430, Subpart B for the test methods.
Thanks for the energy star link. I started to look into energy star earlier, but than I thought I should double check whether the quoted power specs were from energy star or whether the fridges in question were even energy star certified, turns out the smaller one isn't (didn't check the larger one as even the smaller one is way bigger than I plan to buy). So it appears the power figures come from manufacturer spec sheets or something, not energy star, but its possible they still follow energy star test guidelines.
You may be right that the test doesn't accurately gauge 'real world use' or that the test wasn't well designed to take advantage of an inverter fridges capabilities (it seems from the miniscule bit that I've read is that one of the main benefits is that the compressor can adjust to the users patterns of use, so in a standardized test this may not be an advantage).
"Hi, I am new here, I want a guide over the following solar components. 1MPPT Hybrid Solar Inverter 3KVA/2400W With 24VDC 60A MPPT Bttery Charger Inverter 30A AC Charger, 6 pieces of 100w 12V Monocrystalline silicon cell solar panel module Tempered glass Aluminum frame with P320 Power Optimizer P320-5NC4ARS 320W each Connected in series and parallel and a pair of 100AH 12V lithium batteries in series. Please can this work without a problem.Thanks
Last edited:
I'm almost certain you did not mean to post this here. This is a post about refrigerators ?.
Post in the beginner section. When you do, consider adding more context and maybe more structure to your post. What are you building? Make it easier for people to help you, you included a ton of good useful information which is good, but it reads like a jumbled wall of specs and numbers, its a bit overwhelming (or maybe I'm just dense). Maybe separate out each component on its own line and link to the product in question, it'll make it easier to read. Best of luck with the build!
Haflerman
New Member
- Joined
- Jan 23, 2020
- Messages
- 3
I can tell you without a doubt, buy the largest ARB fridge you can afford. I have a 65 liter ARB and have used it off and on for the past 7 years. Never let me down and keeps ice cream frozen when it was 130deg inside the van camping in Death Valley, CA. Low power draw, even at startup and will fast freeze a cows quarter in less than 2 hrs. Dometic stuff is crap IMHO. Including the 3-wayfridge that VW put in my Westfalia! I removed the fridge, saved 40+lbs and have a portable workhorse that is perfect for camping or VanLife.
Attachments
Last edited:
I think your idea will work just fine. We are doing something very similar.
We are going with this genius guy's idea using a mechanical thermostat that has a relay controlled outlet with the sensor placed inside a top opening freezer. Going to dedicate a sized inverter to the freezer (set on fridge temps) and control the inverter via the relay/cutoff outlet, this way the thermostat switched outlet will turn off the inverter and the fridge when it is up to temperature. The inverter only runs when the fridge needs to run and the freezer is better insulated than a dorm fridge and is top opening as well. The freezer is "cheap as chips" and the thermostat is relatively cheap as well. This also gives you the option to run the unit as a freezer at times if that suits. Info on the components are in the video.
We are going with this genius guy's idea using a mechanical thermostat that has a relay controlled outlet with the sensor placed inside a top opening freezer. Going to dedicate a sized inverter to the freezer (set on fridge temps) and control the inverter via the relay/cutoff outlet, this way the thermostat switched outlet will turn off the inverter and the fridge when it is up to temperature. The inverter only runs when the fridge needs to run and the freezer is better insulated than a dorm fridge and is top opening as well. The freezer is "cheap as chips" and the thermostat is relatively cheap as well. This also gives you the option to run the unit as a freezer at times if that suits. Info on the components are in the video.
Last edited:
Similar threads
