My new Apartment Refrigerator

[Group9]

I’ve often thought that one possible solution to the whole refrigeration power issue, would be to put a 120 volt fridge on its own separate, inverter/battery/solar/charging circuit, where it couldn’t affect the main house battery system at all.

If you have the room, which we do, for such an extra system.

 

[Comodave]

I am sure it happens, but in all my years I have never seen one on the road on fire. Sounds like an extremely low probability event. I would bet the insurance companies don’t care.

Gordon

Actually I bet your insurance company would care. The RV fridges are not approved for marine use. They are not designed to run off level more than a few degrees or the solution will start to beke into flakes and the the system will plug up and the refer is junk at that point.

 

[FlyWright]

If we all had 60 foot boats, we could all carry more batteries. I would hard pressed to find room for another battery box, and have to make do with 2 8Ds for a house bank. I find my u-line ice maker is my biggest consumer. We make a tub of ice, bag it and put it in our chest freezer so I can shut off the icemaker.

Gordon

If you have an additional inch or two of vertical clearance, you could expand your battery bank capacity by almost 50% without changing the footprint. I did this years ago by replacing my 2 8D batteries with 6 golf cart batteries and gained 47% capacity in AH. (450AH vs. 660AH)

 

[foggysail]

I am sure it happens, but in all my years I have never seen one on the road on fire. Sounds like an extremely low probability event. I would bet the insurance companies don’t care.

Gordon

If my Ipad had not failed (replaced with insurance) I could show some pictures I took of a motor home completely engulfed in flames. This occurred last summer on Rt 95 in North Attleboro MA. Of course, I have no idea what caused the fire but I certainly know there was a fire with flames 20-30' at least into the air.

https://www.thesunchronicle.com/new...cle_ec46aaad-5e9c-557d-8c7b-9cc203ec10cb.html

 

[foggysail]

If we all had 60 foot boats, we could all carry more batteries. I would hard pressed to find room for another battery box, and have to make do with 2 8Ds for a house bank. I find my u-line ice maker is my biggest consumer. We make a tub of ice, bag it and put it in our chest freezer so I can shut off the icemaker.

Gordon

Yeah, I can understand limited battery capacity. But one does not need a 60'er. Mine is only 40, I carry 8ea 6v golfcarts rated at a total of 860 AH which are charged with my 4 295W solar panels. My fridge is about 8.3 cuft or so with self defrost. Solar has no troubles keeping my batteries charged. My boat is still on the hard waiting for better weather. It is ready to go so I activated my fridge.......to keep some soda cool and things just chug away.

 

[FF]

"The RV fridges are not approved for marine use. They are not designed to run off level more than a few degrees or the solution will start to beke into flakes and the the system will plug up and the refer is junk at that point."

House refrigerators and freezers also are " not approved for marine use..

Doesn't seem to bother anyone.

Propane reefers from the 50-60-70era were a problem with being off level for long periods of time .

The new units operate fine if the RV is level enough to stay in bed with out a belt.

Modest motion actually helps the circulation .

We have a couple of decades on our antique propane reefer, made by Motorola , before Dometic took the line over. Ours is on a self draining aft cockpit , but I have seen others mounted inside , just properly vented .

I would never again outfit a boat without a propane reefer , which is probably saying a lot as our 90/90 only requires 2 hours of engine operation to bring down eutetic plates that hold ice cream at 5F for 3-4 days.

Every 18 -20 days we change propane bottles , lots better than any alternative!

 

[O C Diver]

Apparently my new apartment refrigerator doesn't consume any battery bank power when on the hook.

I've been repeatedly asked how much power the unit consumes including the inverter idle consumption. So I finally got around to doing a test.

The test:
After the unit had been running and temperature stable for a few days, I ran a 24 hour test from 12 noon to 12 noon. I set the air conditioner at 80 degrees upper limit and recorded cabin temperatures from 72 to 80 degrees. The refrigerator is in the upper 30s and the freezer was just above 0 degrees Fahrenheit.

With everything else turned off (including the refrigerator), the inverter (Magnum Energy MS 2812) draws 2.9 amps at 12.5 volts according to my Vicktron Battery Monitor. When you turn on the circuit for the refrigerator and the ventilation fan (fan runs continuously) without the refrigerator compressor running, the power consumption goes up by .15 amps according to the battery Monitor. So, the total power consumption of the inverter and refrigerator circuit without the compressor running is 3.05 amps at 12.5 VDC, or 38.125 watts. This 38.125 watts over 24 hours equals 915 watts or 73.2 AH (Amp Hours).

So, of the power consumed in 24 hours, the inverter and non compressor consumption is 73.2 AH. You'll want to remember that number.

So I started the test with my battery Monitor reading 100% state of charge. Waited for the compressor to run for a while and watched the battery monitor drop to 99.8% state of charge. When I returned to the boat the next day, the state of charge was down to 92.5%. The refrigerator and the inverter had consumed 7.5% of the battery bank. My battery bank is made up of Trojan T-105s. 4 pairs gives me 900 AH. 7.5% of 900 AH is 67.5 AH. You'll want to remember that number also.

So, the test consumed 67.5 AH. Of that 67.5 AH, 73.2 AH were consumed by the inverter and refrigerator circuit without the compressor. So, my refrigerator compressor and frost free function consumed -5.7 AH.

I'm sure someone can explain this slight discrepancy to me. Frankly, I don't care. Consuming <8% of the 900 AH battery bank in 24 hours is all I care about.


Ted

 

[dhays]

I'm sure someone can explain this slight discrepancy to me. Frankly, I don't care. Consuming <8% of the 900 AH battery bank in 24 hours is all I care about.

I can't explain the discrepancy, but I think you may be optimistic about the 900 Ah battery bank. Battery capacity is a guess, unless you have the means to do a load test. My own house bank should have been 780 Ah when the batteries were new. I have no idea if that really is the case or not. I seem to recall CMS suggesting that a battery bank often will lose about 5% capacity per year.


So I would take that 8% number with a grain of salt because the 900 Ah is likely a WAG.

 

[FlyWright]

Ted, I bet you're putting too much faith in that % of charge remaining and it's causing fuzzy math results. The SOC% is known to drift on many of these meters. That's apparently what makes the Balmar SG-200 so unique in its ability to track Battery health and SOC so accurately.

Do you have a Kill-a-watt meter? If so, plug it into the fridge and let it do its monitoring for a 24 hr period. It'll provide an independent source for the watts consumed during that period.

 

[O C Diver]

I can't explain the discrepancy, but I think you may be optimistic about the 900 Ah battery bank. Battery capacity is a guess, unless you have the means to do a load test. My own house bank should have been 780 Ah when the batteries were new. I have no idea if that really is the case or not. I seem to recall CMS suggesting that a battery bank often will lose about 5% capacity per year.


So I would take that 8% number with a grain of salt because the 900 Ah is likely a WAG.

Think you missed the point of the last paragraph. While the 8% may not be super accurate, the Norcold number without the inverter would have been a much higher percentage. I only care that I'm consuming far less than I was with before and have a far superior refrigerator.

Ted

 

[O C Diver]

Ted, I bet you're putting too much faith in that % of charge remaining and it's causing fuzzy math results. The SOC% is known to drift on many of these meters. That's apparently what makes the Balmar SG-200 so unique in its ability to track Battery health and SOC so accurately.

Do you have a Kill-a-watt meter? If so, plug it into the fridge and let it do its monitoring for a 24 hr period. It'll provide an independent source for the watts consumed during that period.

Al, first of all, "unique" is absolute. Either it is or it isn't.

The Victron gauge is supposed to be pretty good. Really doubt the Balmar gauge offers a meaningful advantage when you're discussing approximate values on a 3 year old open lead acid battery bank. The math in my post was done tongue in cheek to show the absurdity of over analysis. My new refrigerator through the inverter draws far less than the Norcold without the inverter. That's all you need to know.

Ted

 

[dhays]

Think you missed the point of the last paragraph. While the 8% may not be super accurate, the Norcold number without the inverter would have been a much higher percentage. I only care that I'm consuming far less than I was with before and have a far superior refrigerator.

Ted

Very true. If your battery bank capacity is smaller than the 900 Ah then your refrigerator is putting even more amps back into your bank. You found the magic fridge that creates electricity while keep food cold!

 

[OldDan1943]

Very true. If your battery bank capacity is smaller than the 900 Ah then your refrigerator is putting even more amps back into your bank. You found the magic fridge that creates electricity while keep food cold!

+1

 

[FlyWright]

I meant unique among the 2" SOC meters we've grown accustomed to. The new Balmar is really heads and shoulders above the average SOC % accuracy. It also provides a State of Health (SOH) that apparently is very good, too.

I noticed a noticeable improvement when replacing my Norcold with a NovaKool. Then when I replaced an old free apt 3-4 cu ft with a new $100 3-4 cu ft, I was very surprised to see another significant difference. (I didn't try to quantify it.)

I agree that these new fangled ice boxes are a great improvement over the old models. What will they think of next?

 

[Rossland]

Good report OC. The only way to get accurate measurements of power use is with a Kill-A-Watt. Nevertheless you showed that modern "domestic" fridges don't use much energy.

I hope someone will do a comprehensive test of 12V fridges.

 

[FlyWright]

It'll only cost you $17.20. Take one for the team. We're dying to know...

https://smile.amazon.com/P3-P4400-E...s=kill-a-watt&qid=1558578978&s=gateway&sr=8-3

 

[Wxx3]

That sounds good.
I also have the Victron BM.
Two things to consider next you measure.
The SOC is calculated using a complicated formula. Just record the difference in Amp hours from start to finish and that will give you the accurate consumption. I'm sure that's why you are getting a negative result.

Your inverter should become more efficient as it has a bigger load, so you can't use that idle figure for the entire period.

The ending minus the beginning amp-hours will give you the number you need.

 

[FF]

"I agree that these new fangled ice boxes are a great improvement over the old models. What will they think of next?"

We are almost finished with the R&R of a 1930's summer cottage , no insulation , no foundation rested on a cedar log, with a modular. Finally finished enough to be looking for a refrigerator and other appliances.

We trolled Consumer Reports and found a Sears (made by LG ) unit that would fit.

Consumer Reports loved it BUT there were multiple reports of early compressor death.

In shopping a talk with a local LG dealer gave something to think about.

When we bought the cottage it had an old small fridge , the freezer section would hold an ice cube tray and perhaps 2 packages of frozen food,It every summer worked for decades.

The dealers claim was the super high efficiency of the new units caused the new compressors to work very hard , he felt a 10-12 year life was doing good.

His opinion was the savings in electric over a decade easily paid for the shorter fridge life.
For us as a seasonal cottage , that's fine as our 6 month season should have the uninit go 20+ years .

For boaters the shorter life of high efficiency AC reefer would easily be acceptable, since making , storing and then converting energy is an inefficient process & expensive process.Solar is a big help!

The alternative like a DC Sunfrost .or a custom reefer built in , with superb insulation and Eutetic plates or a DC compressor would be way more boat bucks.

To my thinking a properly installed propane RV reefer might be the best solution , lowest cost , long life , and easiest to live with.

This does scare folks that have never lived with the system , but it is grand for the marina adverse folks.

 

[O C Diver]

It'll only cost you $17.20. Take one for the team. We're dying to know...

https://smile.amazon.com/P3-P4400-E...s=kill-a-watt&qid=1558578978&s=gateway&sr=8-3

The purpose of the test was to measure total consumption of the refrigerator and the inverter over a 24 hour period. Unfortunately that meter isn't going to include the inverter consumption.

Ted

 

[koliver]

Apparently my new apartment refrigerator doesn't consume any battery bank power when on the hook.

So, the test consumed 67.5 AH. Of that 67.5 AH, 73.2 AH were consumed by the inverter and refrigerator circuit without the compressor. So, my refrigerator compressor and frost free function consumed -5.7 AH.

I'm sure someone can explain this slight discrepancy to me. Frankly, I don't care. Consuming <8% of the 900 AH battery bank in 24 hours is all I care about.


Ted

I am going to order 5 of those fridges for my boat. That will solve my power consumption requirements altogether. In fact I only need 4, because I can get rid of my DC fridge and save another few amps.

I don't think a % left WAG is at all helpful to your experiment. You need to do an actual measurement of power consumption while your fridge is running its compressor, and put the fridge line on a timer so that you know how many hours of compressor time occur in a 24 hr day. Then give us your results.
Of course you are already ahead on what needs to be done and we all agree with you that it isn't something we would expect anyone to spend time or money investigating to that degree.

Love your boat!

 

[Rossland]

The purpose of the test was to measure total consumption of the refrigerator and the inverter over a 24 hour period. Unfortunately that meter isn't going to include the inverter consumption.

Ted

But your inverter owners manual will tell you how much power it consumes in the conversion. A Magnum is about 90% efficient, and Victron Multiplus is about 93%

When testing a fridge, you should test it for 5 to 7 days, then average the result. Then add on 10%, or whatever your inverter consumes, to get an accurate number on battery draw.

We tested our fridge with a Kill A Watt, and found that there was a large variation from day to day. A lot more power was consumed on days when we opened the door a lot, and provisioning day when we put a lot of warm items in the fridge was even worse. Outside air temp had an effect too, so we could reduce fridge energy consumption by running the A/C.

However, this degree of precision may not be necessary for your purposes.

 

[Heron]

I also have the Victron BM.
Two things to consider next you measure.
The SOC is calculated using a complicated formula. Just record the difference in Amp hours from start to finish and that will give you the accurate consumption. I'm sure that's why you are getting a negative result.

Forget SOC. IMO, the only meaningful measurement would be Amp Hours consumed. Over a couple of years of cruising, with my 30 yr old 12/110 Norcold, my 24 hour consumption averaged 125 Amp/hour. All in, fridge, lights, stereo, TV etc. We anchor out a lot. With the new 12/110 Isotherm, with only a few days on the hook, that has dropped to about 80 amp/hrs. No generator, 4 GC's.....The new stuff is considerably more efficient. There is even a control system for the Isotherm that will make it more efficient, but at these numbers I see no real need...

 

[Crusty Chief]

Hi Ted!

Thanks so much for the great thread! We just installed our summit and man oh man the difference is amazing. Life with the Admiral is so much better. Bigger capacity, hardly runs at all and so quiet. Have no idea why it’s taken us this long, but its done.
We did pre wire a 12 volt line for a circ fan if needed. Have you needed your’s or do you just run it anyway? Finishing the cabinet work now.
Big thumbs up again!

Cheers!

 

[O C Diver]

Hi Ted!

Thanks so much for the great thread! We just installed our summit and man oh man the difference is amazing. Life with the Admiral is so much better. Bigger capacity, hardly runs at all and so quiet. Have no idea why it’s taken us this long, but its done.
We did pre wire a 12 volt line for a circ fan if needed. Have you needed your’s or do you just run it anyway? Finishing the cabinet work now.
Big thumbs up again!

Cheers!

Congratulations! Glad the admiral is happy with it. You might offer to take over the freezer defrosting duties. My fan is 120 VAC and runs continuously when the refrigerator circuit is on. I've thought about trying it without the fan, but it's silent and draws so little power that it won't matter as far as energy consumption. Also, nothing good is going to come from reduced air flow over the condenser. So, I'm going to let mine run and focus on the next project.

Ted

 

[foggysail]

Crusty-- IF you have space and have not yet installed solar, it is the gift that keeps on giving! YOur batteries will say thank you.

 

[John E Holden]

Looking for info for my conversion

I too am a member of the the "I am sick of warm beer club" and have had it with my Dometic Tundra fridge which has constantly let me down over the last 10 years. Previously I had a Norcold installed and thought the Dometic was going to be the cats meow. Anyway enough of that and onward to greener pastures. I might have a little problem in the fact that my fridge is an under counter type and is limited in size as opposed to the big boy fridges that you all are talking about. My current Hot Box (measured at 50 degrees this weekend) is a Dometic Tundra T32 has approx 3.2cf of storage. In my research I found that a Magic Chef HMR440SE 4.4cf will fit in the same space. But I would need to add an inverter. The MC draws 1.5 amps 180watts according to the label on the back. What size inverter would I need to power this puppy efficiently while on the hook? I understand the concept of startup power of motors and know I need to oversize to accommodate this. I am not planning on putting other AC needs online while on the hook, just the fridge. I have 2x8D batteries and a 24M thats dedicated to the windlass. I currently have a fan that blows air out of the box where the fridge sits but would I need one closer to the condenser?


Any advise would be very appreciated

 

[foggysail]

I too am a member of the the "I am sick of warm beer club" and have had it with my Dometic Tundra fridge which has constantly let me down over the last 10 years. Previously I had a Norcold installed and thought the Dometic was going to be the cats meow. Anyway enough of that and onward to greener pastures. I might have a little problem in the fact that my fridge is an under counter type and is limited in size as opposed to the big boy fridges that you all are talking about. My current Hot Box (measured at 50 degrees this weekend) is a Dometic Tundra T32 has approx 3.2cf of storage. In my research I found that a Magic Chef HMR440SE 4.4cf will fit in the same space. But I would need to add an inverter. The MC draws 1.5 amps 180watts according to the label on the back. What size inverter would I need to power this puppy efficiently while on the hook? I understand the concept of startup power of motors and know I need to oversize to accommodate this. I am not planning on putting other AC needs online while on the hook, just the fridge. I have 2x8D batteries and a 24M thats dedicated to the windlass. I currently have a fan that blows air out of the box where the fridge sits but would I need one closer to the condenser?


Any advise would be very appreciated

John— One important consideration pertaining to inverter size is if the fridge has self defrost. My Summit now is at least 10 years behind it........my how time flies by. I purchased a Xantrex 1kw pure sine wave inverter at the same time as my fridge which seemed to work OK. The power drawn during normal operation was low.......I forget just how low but in the 200-300 watt range. However, when the self defrost engaged, wattage jumped to over 800 watts and lasted for about 5-10 minutes.

The inverter squawked every time the defrost cycle started. I also got around to killiing that inverter by attempting to power my microwave with it. Not a fan of Xantrex even though I abused that inverter.

My recommendation is to use nothing less than a 2kw true/pure sine wave inverter. They are relatively inexpensive. I also recommend that if you do purchase something inexpensive that you power your fridge 24/7 with the inverter rather than just while away from dock power UNLESS you purchase one with an internal power transformer or install a separate dedicated isolation transformer. Now this is MY opinion and I am NOT going to get involved in a peeing contest with others who have different opinions.

 

[DavidM]

John:


I believe that your basic problem is lack of cooling of the condenser which is on the back side of the fridge. If it is installed in a blocked off space then the air behind it gets stagnant and warm and it won't cool well. That problem will be made even worse with a less efficient dorm type 120V fridge.


Find a way to cut out louvers above and below the fridge and put a 12V DC fan in the back to exhaust the hot air (or blow fresh air inside).


FWIW the 180 watt dorm type fridge will draw about 15 amps from your batteries to power an inverter and from what you describe, it will run all of the time, thereby using 360 amp hours each day.


David

 

[rsn48]

So here is the high tech expensive solution but it will work and work well.

1. Replace with a Norco 12 v only.
2. Add insulation to the Norco, no matter how little is better than none.
3. Use a fridge optimizer
4. Replace your batteries with Fireflies, which can be taken down 80 % and rebound back just fine. Each battery is 116 amps so four of em is 464 amps with 370 usable amps.
5. Add a 210 Efoy which will keep your batteries topped up when the cruising engine doesn't complete the job. No noise from a generator.

With the extra amps and Efoy, you can use a microwave (usually used about 10 minutes max a day), a toaster, and I even use a 1380 watt convection oven (remember the heat aspect of the oven is only on about half time, the small fan is on full time during the cooking).

 

[John E Holden]

John— One important consideration pertaining to inverter size is if the fridge has self defrost. My Summit now is at least 10 years behind it........my how time flies by. I purchased a Xantrex 1kw pure sine wave inverter at the same time as my fridge which seemed to work OK. The power drawn during normal operation was low.......I forget just how low but in the 200-300 watt range. However, when the self defrost engaged, wattage jumped to over 800 watts and lasted for about 5-10 minutes.

The inverter squawked every time the defrost cycle started. I also got around to killiing that inverter by attempting to power my microwave with it. Not a fan of Xantrex even though I abused that inverter.

My recommendation is to use nothing less than a 2kw true/pure sine wave inverter. They are relatively inexpensive. I also recommend that if you do purchase something inexpensive that you power your fridge 24/7 with the inverter rather than just while away from dock power UNLESS you purchase one with an internal power transformer or install a separate dedicated isolation transformer. Now this is MY opinion and I am NOT going to get involved in a peeing contest with others who have different opinions.

The Fridge is manual defrost