AcuTemp Refrigerator

[rustystud]

Rusty,
Would you mind taking the top plastic cover off and taking pictures of the batteries and maybe getting some measurements off of them please? This would be so helpful. Unless you know off top of your head

Their basically the size of Motorcycle batteries.

 

[gimpyrobb]

I've got an Acutemp fridge as well! Ordered new 22ah batteries from Amamzon for about $87.00 (for two).

So it seems the dimensions are very close on most of the batts I've found. Did your larger batts fit w/o modifying the batt tray? Could you post a model number?

 

[DieselAddict]

As a "Federally Certified HVAC Technician" I can truthfully state that the "average" refrigerator/freezer's Compressor today uses only 25 watts. The rest of the power consumed is for all the little bells and whistles like lights and fans and sensors and on and on. Also "watts" is "Watts" no matter what. Whether it is AC or DC it doesn't matter. As far as the size being an indicator of power that is ridiculous, especially in todays world of "extreme magnets" . Haven't you seen the size of modern diesel engine starter motors ? Compared to motors from the 1950's they are absolutely tiny ! Modern electronics and powerful magnets make this possible. As far as the size of the "evaporator" and "condenser" goes, they are equivalent in size (if not bigger) to the modern hotel room refrigerator. Another thing you mentioned is hot items taking longer to cool down. Didn't you take "Physics" in school ? Don't you remember all those experiments cooling down hot items ? Since the "atoms" of a heated item move faster when hot, they also give off hear quicker then cool atoms do.
Since there is all this confusion about this refrigerators ability to cool or freeze something I'll also test mine tomorrow. I'll put some water jugs in it and see how long it takes to totally freeze them too.

I await your results with baited breath.

 

[NATCAD]

Can anyone confirm what battery model # they have used that successfully fits in without modifying the tray?

 

[firefinder]

There are actually three batteries in the units. Two main batteries wired in series and a third, small battery for processor and memory.

(2) PowerSonic PSH12180FR 12 Volt, 21 Amp/Hr

[FONT=&quot](1) Tadiran TL-5104, 3.6 Volt, 2.1 Amp/Hr

I have ordered the batteries from Amazon in the past.

There is also a battery holder that clips to the processor board to hold the Tadiran battery in place. Digi-Key Part Number 36-1028C-ND, Keystone Electronics 1028C.

Attached are a couple of photos to clarify.




Hope these photos help.
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[rustystud]

I await your results with baited breath.

Sarcasm doesn't suite you.
As of this moment the water bottles have been in the freezer for 3 hours. I checked them and they are all "slushy ice" . In a few more hours I expect them all to be frozen solid.

 

[rustystud]

Well I just checked the water bottles and their all frozen solid. That's 2 gallons of water. So somewhere between 3 and 6 hours they froze. According to the internet most small freezers can freeze water solid in 6 hours and the standard freezer can do it in 3 to 4 hours. So this unit is right on the mark for a normal freezer. Actually since the water was already slushy at 3 hours it probably froze solid much sooner then the 6 hour mark. Either way it will freeze a liquid in a normal amount of time.

 

[maa45069]

Thank you for the test

Sent from my SM-G935T using Tapatalk

 

[DieselAddict]

Sarcasm doesn't suite you.
As of this moment the water bottles have been in the freezer for 3 hours. I checked them and they are all "slushy ice" . In a few more hours I expect them all to be frozen solid.

Only being a little sarcastic in response to the tone in your response. I'm more than slightly interested in this kind of stuff. I love this stuff. I'm that kind of geek. And I'm not afraid to be wrong.

I've started a capacity test here at the house on one of my units. Photos of the setup and the initial data charts here - https://photos.app.goo.gl/H1Tp2Z9jPTCIr3XN2

The two green traces on the one chart are the milk jugs. The orangish trace on that same chart is the condenser discharge air temp. I'm not using that for any actual calculations. Just curious about the cycling of the compressor as things progress. Each of the milk containers has a measured 4lb and 4oz of water in them.

The second chart with the red and green traces is the current outside temperature here at the house. The units are outside.

When I placed the milk containers in the unit the chamber temperature rose high enough to alarm. You can see in the photos I put a small cooling rack in the bottom of the chamber to keep the milk containers from touching the bottom or the sides. Wanted to encourage as much airflow as possible for best heat transfer.

Based on the standard heat of fusion of water this mass represents about 1290 kJ of energy. Using the temperature and time data we should be able to calculate the approximate thermal capacity of the system as a whole.

I'll update the data in the image folder above as things progress. If anyone is enough of a geek to want to see the data in real time you can drop me a PM. The unit I'm using to capture the data is online.

Edit - In the first hour the containers have dropped 16 degrees. They have a total mass of 8.5lbs. That equals ~135 btu/hr.

 

[DieselAddict]

The containers have both reached 32 degrees. The trend has flattened out as expected. Looking at the rate of cooling the estimate of about 135 btu/hr is holding up. Assuming this energy transfer rate continues it should take approximately 9 hours to completely freeze 8.5lbs of water.

The compressor has not cycled off since the test began.

 

[rustystud]

The containers have both reached 32 degrees. The trend has flattened out as expected. Looking at the rate of cooling the estimate of about 135 btu/hr is holding up. Assuming this energy transfer rate continues it should take approximately 9 hours to completely freeze 8.5lbs of water.

The compressor has not cycled off since the test began.

What's your outside air temperature ? I did my test inside with a temperature of 70 F . I would be surprised if your's actually takes 9 hours to freeze solid though. Unless it is not performing properly.
My initial temperature rose to -10 C after putting in the water bottles, from a temperature of -23 C . It stayed there for the first three hours. After that it started to go down rapidly. Like I said earlier, this unit performs like any standard freezer. It just has the ability to use 12V, 24V and 120 Volt AC and internal batteries to power itself.

 

[DieselAddict]

What's your outside air temperature ? I did my test inside with a temperature of 70 F . I would be surprised if your's actually takes 9 hours to freeze solid though. Unless it is not performing properly.
My initial temperature rose to -10 C after putting in the water bottles, from a temperature of -23 C . It stayed there for the first three hours. After that it started to go down rapidly. Like I said earlier, this unit performs like any standard freezer. It just has the ability to use 12V, 24V and 120 Volt AC and internal batteries to power itself.

Here are the trends so far. The jugs are just about frozen based on the temperature getting a little noisy. 9hrs is looking like a reasonable estimate based on the calculations during the initial cool-down of the jugs.

Once this test is done I'll reset and test the other unit then do one with the inside freezer as a comparison.

 

[rustystud]

Here are the trends so far. The jugs are just about frozen based on the temperature getting a little noisy. 9hrs is looking like a reasonable estimate based on the calculations during the initial cool-down of the jugs.

Once this test is done I'll reset and test the other unit then do one with the inside freezer as a comparison.

You do realize your taking this way to seriously right ? That's OK though. Good data is always useful.

 

[rustystud]

I forgot to ask DieselAddict . Was your freezer already at operating temperature when you put the water bottles in (-23C) ? Or did you put in the water bottles and then turn it on ? That will make a huge difference.

 

[DieselAddict]

You do realize your taking this way to seriously right ? That's OK though. Good data is always useful.

That personality trait is for me both a gift and a curse.

The unit was running about 14 hours when I started the test. It was at temp (-23c) and running normally.

 

[rustystud]

So what is the temperature now ?

 

[gimpyrobb]

So what is the temperature now ?

Cold.

 

[DieselAddict]

Sorry I dozed off. The graph shows that it took about 10 hours to freeze the jugs solid. That is in line with the rate of cooling during the initial cool-down of the jugs to the freezing point.

If we take 10 hours as the total time that gives us a thermal capacity of the system of ~122 btu/hr.

This doesn't give us the capacity of the refrigeration system specifically but the total excess cooling capacity of the system as a whole. This includes things like insulation quality, ambient conditions, and even dirt on the condenser.

Since I have 2 of them available I'll reset and run the test again on the other one.

 

[NATCAD]

Cookie monster likes data cookies! Nom nom nom nom!

Sorry, seriously, thank you for doing this. Looking forward to the next cooler test to see if uniform.

Regarding the unit for data - I see it is named bbq - do you bbq remotely?? That is great if so.

 

[DieselAddict]

Yea, I'm using the temperature controller for my smoker for this. It is my go-to temperature collection setup. It works great for most things like this. When its not keeping an eye on some texas style brisket its monitoring the temperature of the solar hot water system.

Ok. System #2 is now under test. Same conditions. We should have a full dataset by morning.

The attached chart shows the cycling of the compressor during the day today. The test officially begins at the far right of the chart where you see the green lines diverge.