It appears all modern fridges are "frost free" and they maintain this state by periodically operating a heating element to melt ice build-up inside the fridge.
I will probably be installing an inverter type fridge into my van and am looking at power consumption - it appears the defrost elements are typically around 400W for smaller fridge/freezers and this added to the compressor running current appears to require a 12V/240V inverter around 600W+.
Does anyone have information regarding how long these elements are turned on for each day?
Calculating from the energy consumption figures given for small inverter fridge/freezers they appear to use around 70Ah per day. I wonder about disconnecting the element and simply defrosting the fridge manually each month or so?
Any comments guys?
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
Two Christmases ago on Christmas day we replaced our 30 year-old Frost free fridge, a Westinghouse 440L
Apart from the power consumption of the old fridge, a topic in itself, it dried out everything in the fridge. Great, except for veggies!
The new one is also a Westinghouse, 340L, simply due to the the fact it was the only model from any manufacturer that would fit in the space without rebuilding the kitchen because modern fridges need air circulation on the sides. The only other one was a Panasonic but it was a bit too tight & the door couldn't open far enough due to a wall.
Anyway, I tested the fridge with an inline submeter on the settings the fridge was set to when we bought it for a few months over January & February. It consumed a whisker less than its energy rating. A good start!
We also noted that the fridge must be using a different type of frost free setup as the veggies in the fridge do not dry out like the previous fridge.
Conclusion. On a sample of one, the fridge's rating is as specified & we do not have "freeze dried" veggies, so we are happy. But we would like another 100 litres! We do have a 100 litre second fridge which is still reasonably efficient even though it is 20 years old.
The key with new domestic fridges is air circulation on their sides for cooling.
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Procrastination, mankind's greatest labour saving device!
50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
Interesting; Ebay sellers suggest Westinghouse use three elements in different sized fridges of about 300, 400 and 500W. Maybe a trip to the Good Guys is called for so I can have a look at some spec. plates.
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
Mike Harding wrote:Does anyone have information regarding how long these elements are turned on for each day?
Calculating from the energy consumption figures given for small inverter fridge/freezers they appear to use around 70Ah per day. I wonder about disconnecting the element and simply defrosting the fridge manually each month or so?
I'm not sure if they all work the same but I did become familiar with one fridge whilst I was working as an RI. I was searching for short bursts of interference that were about 10 seconds long and occurred intermittently ar regular periods. The interference wiped out the signal of the ABC local radio signal in South Durras. It was traced to a fairly new fridge. After each cycle of its compressor, there were 10 or so seconds of interference. The contacts supplying power to the defrost unit were arcing and producing the interference.
The cooling unit in the fridge was a small heat exchanger. Being small, it iced up quickly and required defrosting regularly as the frost would build up very quickly and prevent any airflow across it. The defrosting took place after every cycle of the compressor. If it did not then the fridge would die quickly. All the other fridges I have observed since have been the same. There may be other systems to cool frost-free fridges but I think they would be small devices and frost up too quickly if they are not defrosted very regularly.
I don't think these fridges would work properly if the defrost heater was disabled.
(Postscript - the fridge owner was extremely p155ed off that his new fridge was faulty. However, he calmed down quickly after he found it would be fixed under warranty.)
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PeterD Nissan Navara D23 diesel auto, Spaceland pop-top Retired radio and electronics technician. NSW Central Coast.
Problem with these fridges is the evaporator is fully enclosed and very efficient so it can easily get totally iced up so now air flows into the fridge - just like a rooftop caravan aircon that once it ices up, you get zero cooling until you manually intervene. Easy to do with an aircon, but not so easy in an inverter fridge. Also not like a conventional fridge with the cooling fins because even totally iced up, there is at least a big lump of ice inside the refrigerated space.
I have a large LG inverter fridge and I just let it do its thing. If power does get tight then since I run it at minimum temperatures 1C in the fridge and - 23 in the freezer, I can just switch it off for up to 24 hours and still maintain good temperatures.
-- Edited by Tony LEE on Monday 12th of April 2021 07:49:46 PM
-- Edited by Tony LEE on Monday 12th of April 2021 07:51:14 PM
I'm not 100% sure but I think it was early 2016, that I extracted a 90l 3way fridge and fitted a Samsung DI 228ltr fridge, 5 years on and some 100,000+ klm travelled with zero issues.
Early in the installation I found the current draw when on battery was approximatly 65ah per day from a 120ah SLA battery with a single 100w solar panel via a Victron 350va Inverter. My inital setup was 120ah/100w panel was a standalone system soley for the fridge, the caravan house battery was 100ah/75w panel and Setec charger, both batteries had Anderson Plug connections to the Utes main cranking battery via a 120amp Sidewinder VSR.
Total cost of the installation was below $1000, Fridge $296, Inverter $120, Battery (special deal store closing) $160 plus some 6 B&S cable and a few bits and bobs to complete the job.
The following year I insulated the fridge cavity with 15mm styrene sheets, and covered them with woven fiberglass fabric.
If and when this current fridge expires it will be replace with a similar domestic fridge.
Once you set up for a domestic fridge. The whole setup is probably cheaper anyway. If the fridge fails, it's not difficult to pick up a cheap replacement pretty much anywhere around the county. Even from a second hand white goods shop to get you out of trouble. If you simply replace the fridge every 5 years you are still way ahead.
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Procrastination, mankind's greatest labour saving device!
50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
My LG inverter fridge is about a metre from the head of my bed and is mostly inaudible. One advantage of the inverter is it ramps up and down for start and stop so no chance of the usual rattle you get from regular compressor operation.
My LG inverter fridge is about a metre from the head of my bed and is mostly inaudible. One advantage of the inverter is it ramps up and down for start and stop so no chance of the usual rattle you get from regular compressor operation.
100% agree, rarely do we hear our Samsung, thats the advantade of a digital inverter fridge, if buying a domestic fridge to install in your van ensure its a digital inverter one, there is a big difference in power consumption, remember there is no big power drag on startup with a DI fridge.
