What is the best chest freezer, thickest insualtion, DC, lowest power use, best warranty

Is there a way to get to .3kw/day with a 8.8cu ft or darned close to it? I am currently using .6kw per day with an 8.8cu ft frigidaire AC off the shelf 300 dollar freezer with paper thin insulation. It runs every 1.5 hrs and it runs for 1-5-2 hrs every time it runs. Its a constant power drain to my batteries.

Looking for 100mm+ insulation. Triple seal lid. DC operation at 24/48v. Multi-year warranty, 5yrs would be good. R134 refrigerant NOT R600 crap.

Doing a quick Google of heavy insulated DC freezers I find several (but not cheap) chest freezers for PV operation. Looking over a few of the spec sheets and manuals they all seem to be 12-24vDC and none of them mention the refrigerant used.

Is it possible to add insulation to your present chest freezer? My small 5ft cube one I added a 1 inch dense foam (R-6) to the top lid attached with 2 sided foam tape. It improved it quite a bit since the lid was cold to the touch without it.

My suggestion would be to acquire a used sundanzer or the like. The insulation on them is more like 4"+. Swap out the compressors. Put the AC compressor components into the DC Freezer. This ofcourse requires draining the lines appropriately and refilling. Also requires the right kind of solder.
Its an idea of mine. I have a 5.1cubic danby 120vac. It also is thin on insulation. I also have a sundanzer freezer with the compressor but with no other components. So I would need to retrofit the ac unit's components to it...

OffGridIdaho said:

Is there a way to get to .3kw/day with a 8.8cu ft or darned close to it? I am currently using .6kw per day with an 8.8cu ft frigidaire AC off the shelf 300 dollar freezer with paper thin insulation. It runs every 1.5 hrs and it runs for 1-5-2 hrs every time it runs. Its a constant power drain to my batteries.

Looking for 100mm+ insulation. Triple seal lid. DC operation at 24/48v. Multi-year warranty, 5yrs would be good. R134 refrigerant NOT R600 crap.

Click to expand...

But what is the internal temperature control set at?

I set mine to it's absolute lowest setting, which is -10 to -12°C. Cycle times are MUCH shorter, about 5 minutes 3-5x per hour in my kitchen at 18-20°C, vs. if the freezer temperature were left at the default setting, which was about -24°C. Looking at my smart plug consumption chart, it shows an average daily use of 0.35 KWHr.

E. Cho said:

But what is the internal temperature control set at?

I set mine to it's absolute lowest setting, which is -10 to -12°C. Cycle times are MUCH shorter, about 5 minutes 3-5x per hour in my kitchen at 18-20°C, vs. if the freezer temperature were left at the default setting, which was about -24°C. Looking at my smart plug consumption chart, it shows an average daily use of 0.35 KWHr.

Click to expand...

what voltage is the freezer? What size is the freezer? 0.35kwh is quite good.

120 volts AC. 7.2 cubic feet. Danby brand, nothing special, was low cost on sale, about $200 USD.

The default thermostat setting used at least double the energy. I did not need to freeze my food to -24°C.

If my battery is low in the evening, I will unplug the freezer for 12-18 hours until the solar starts up again. Food stays frozen at -10°C, the lowest thermostat dial setting. But my average 3.5 KWHr does not include unplugging it. 0.35 KWHr is my average normal everyday use with the freezer at 1/2 to 3/4 full, though right now it's a bit lower than 1/2. Some days it's lower and some days, though very few, it's higher than 0.35 KWHr. I also only have a 100 AHr 24 volt battery.

Also helpful I think is adding that my 2 120 VAC chest freezers run off my 4KW Low Frequency pure sine wave inverter 24/7. I only unplug the freezer overnight if my 100 AHr LiFePO4 battery is low and I can't or do not want to run the fossil fuel generator to to them up to get it through the night or I don't use any other appliances. This works well. I have enough solar panels at 2.3 KWs but another battery for low solar and night use would be ideal but presently is not affordable. Where I live, with shipping, another LiFePO4 battery costs as much as 2 KW of solar panels, the latter which, won't power anything at night.

With panels getting as cheap as they are these days, I think a more cost-effective solution is just to add more solar. For my freezer in the workshop, I don't even bother to monitor consumption, because with 2000W of solar, I never have a deficit, even in December.

What's your system specs, battery voltage, array wattage, ect?

0.350 kwh per day should be possible based on that there is several AC models in European market archieving that. Not familiar with US models or search engines.

When I've measured it, our Frigidaire 14.8 Cu. Ft. - FFCL1542AW has been between 300 and 500 Wh/day in the winter depending whether we're opening it and adding stuff or not. The temperature setting we've got it set at keeps the bottom around -18C and the top around -12C. We keep it completely full of food - or ice otherwise.

I haven't measured it in the summer, but at least for my system that doesn't matter very much since there's plenty of solar power to be had in the summer.

Datapoints:

4.84 kWh over 366 h (15.25 days) ending 2022/12/30 14:48 PST = 317 Wh / day
0.91 kWh over 41.82 h (1.75 days) ending 2023/01/01 09:24 PST = 522 Wh / day

Here’s the outdoor and internal freezer temperatures over those ~20 days:



Note #1: the internal temperature and power usage went up in the last few days because we put a bunch of food in and it is still working on reaching equilibrium.

Note #2: You can see the frequency that we open the freezer by noting the little spikes in the yellow line. We do try to open it pretty infrequently so this data might not be very representative.

Click to expand...

1.35 kWh over 82.18 h (3.42 days) ending 2023/01/04 20:13 PST = 395 Wh / day

Here’s the outdoor and internal freezer temperatures over those ~4 days:

Click to expand...

MichaelK said:

With panels getting as cheap as they are these days, I think a more cost-effective solution is just to add more solar. For my freezer in the workshop, I don't even bother to monitor consumption, because with 2000W of solar, I never have a deficit, even in December.

What's your system specs, battery voltage, array wattage, ect?

Click to expand...

2000W of solar is only part of the requirements. Enough battery power is also required to run things when there is no solar or not enough solar.

Solar panels may be inexpensive for some, but do not help during the night and LiFePO4 batteries are not inexpensive.

E. Cho said:

2000W of solar is only part of the requirements. Enough battery power is also required to run things when there is no solar or not enough solar.

Solar panels may be inexpensive for some, but do not help during the night and LiFePO4 batteries are not inexpensive.

Click to expand...

That's another hallmark of poor design. Not enough battery compared to not enough solar. Poor design paired with going cheap.

Then skip the Li batteries completely. This is what I am using right now for my own system, and they perform very well. Definately keepers! I'm expecting these to last me the full 20 years they claim to last. The key to long, reliable service with LA batteries is abundant charging amps.

Because it seems all the new small chest freezers radiate the captured heat from the cabinet sides it isn’t possible to thicker-up the insulation.

I wanted to build a super-efficient 12V compressor fridge and had contacted JC Refrigeration about buying components but they wouldn’t provide pricing for the ancillary parts to build one with 4” walls. I haven’t picked back up on the quest.

Anyways they have components that would work for a freezer- you just have to source the ancillary parts elsewhere. They offer 12V and 24V compressors. If you built your own you could have a perfect freezer. Most commodity refrigerators and freezers are very poorly insulated.
Building one with super thick sides top and bottom with a separate external coil arrangement would probably exceed the efficiency of anything of any quality that is retailed.

For DIY insulation vacuukm insulated panels would be probably ultimate option but sizes probably wont match existing freezers.

vacuum insulated panels are still sort of rare but Digikey has actual stock available and prices listed visible to anyone.

MattiFin said:

For DIY insulation vacuukm insulated panels would be probably ultimate option but sizes probably wont match existing freezers.

vacuum insulated panels are still sort of rare but Digikey has actual stock available and prices listed visible to anyone.

Click to expand...

I looked at those and a marine cooling unit but power use was still in the 1/2kw per day range and the marine freezer units could only do 4.7cu ft. The larger units used much more power.

Someone need to come up with a better way of cooling a freezer.