Chinese 12V Fridge

[William_H]

Just saw one of these in local auto parts accesories store for $A500 thats 200 quid to you folks in winter. It is described as "Great Gear " 12 volts 76 litre 100 watt 8.2 amp made in China. It appears to be compressor type with tubes formed in aluminium in the lining for evaporator and tubes in a vemtilated box at the end where there is a computer type fan. ( hard to see the compressor) It has a LED temp readout with up and down buttons for the thermostat. Box claims to -15degrees in 3 hours. Has anyone any experience of these things? it seems good at about half price of an Engel or simil;ar. Tghanks inanticipation will

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[Talbot]

8 amps! going to install a generator as well? There are a number of caravan fridges that work on a similar principle and similar costs, but not a lot of use for boating.

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[charles_reed]

Compressors

8 amps is not so much higher than dedicated marine cooling units - my ASU (probably the most economical unit on the market) uses 4.5 amps in eco mode and 5.8 when in supercool mode.

From the description and the consumption I would guess the unit is not an absorption one to which you allude - the consumption for one of those would be in the range of 15-20 amps.

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[Rohorn]

Hi....some times you win, other times not...with Chinese stuff. I bought a Chinese made 1.5 kw inverter recently. Worked fine for short time then consistently cut out overheating. The tiny computer type fan fitted had disintegrated. I found a hair-drier, gutted out the fan, which by luck was 12v, and installed that. With a solid blast of air you can really feel through the unit, it drives microwave, wet and dry vac etc in Greek island heat with no problems.
So, you may have to do some fixing, but with luck you'll still come out ahead.....
...but as Talbot says, 8 amps is a lot. My 12 year old danfoss powered fridge (S.A. built 75 litre capacity) only takes 4 to 5 amps while running, about 50% in the summer. The insulation may not be great on a Chinese one either.
Cheers......R

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[Ships_Cat]

Errr - we probably get through over 200 AHr per day for refrigeration (frig & freezer) on a 40 foot sailboat. So probably depends on what ones aspirations are as to whether 8 amps is alot or not.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[Talbot]

Re: Compressors

For a 100 litre fridge, you would not need anything more than a Danfoss 35 (used by most marine refridge specialists - see <A target="_blank" HREF=http://www.penguinfrigo.co.uk/pdfs/K35F.pdf>here</A>). For this sized fridge it runs at abt 2500 rpm and this draws 38w With a proper installation you would expect less than 50% cycle, thus a total of 37.2 amp/hrs/day.
I would expect the insulation on this chinese fridge to require a duty cycle of at least 66% (some require considerably more than this) and that would consume 128 amp/hrs per day.

Now I am nor Einstein, but that would appear to be almost 3.5 x a proper system! /forums/images/icons/smile.gif

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[Talbot]

Must assume that you have separate fridge and freezer, and that both are quite large, as 200 amp/hrs seems very large! What sort of compressors and how much insulation?

Most efficient system is a combined fridge/freezer, where the insulation is at least 6" of proper foam designed for this task. The plate is in the freezer section, and a small computer style fan draws cold air from freezer to fridge. With a Danfoss 50 unit, you should be able to run both an 80 litre freezer and a 100 litre fridge simultaneously. assume a duty cycle of 66% in summer (excessive - should be less) and a maximum motor speed, then power requirement should be 107 amp/hrs. Therefore can only assume that your system is much larger than this or is rather inefficient!

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[Ships_Cat]

Re: Compressors

The refrigerator referred to may actually very well be a load of crap, but your analysis is made with no knowledge of the unit's refrigeration capacity so does not show that to be so.

For example, the unit may be super efficient but just draw alot of amps because it has a high refrigeration capacity unit in it, in which case its run time will be very much less than you say. Alternatively, the unit may have a very low refrigeration capacity (ie very inefficient) in which time its run time will be long and total consumption very high.

If you have a look at the specs for high quality 12 v units, say such as those used for meds, etc, you will find that often a 50 litre one will draw the same current as the 100 litre one from the same manufacturer. That only because they both have the same refrig unit in them - the run time is less on the smaller refrigerator than the big one, so while they draw the same current when running, the daily draw is much different. Thus current consumption in amps is not an indicator of efficiency unless you know the size of the actual refrig unit - AHr's used is though but we do not know that in the case of this refrigerator.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[Talbot]

Re: Compressors

That is actually not correct for the Danfoss units They are designed to be run at different speeds for different fridge capacities/cooling requirement. thus I quoted the Danfoss 35 unit at a very low setting (sufficient for 160 ltre fridge), whereas the same unit is capable of cooling up to a 350 litre fridge (or 80 litre freezer) would use more power - again assuming a 50% cycle this would require 72 amp/hrs per day. The figures I quoted for the Danfoss 50 are the maximum for that unit.

IIRC the Danfoss units are made in Italy and are used worldwide. part of the efficiency is use of the correct evaporator/holding plate for your system (depending on how you use the system. If you use a holding plate and high capacity compressor cause you run the engine to cool down the fridge/freezer, then your system will be MUCH less efficient than an evaporator system designed to be run from battery/solarpanel/wind generator combination.

Either way (as I said before) Your system is either inefficient or a lot larger than the system I quoted!

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[Ships_Cat]

Re: Compressors

<<<Your system is either inefficient or a lot larger than the system I quoted!>>>

If you are referring to the 200+AHr for my own system that I mentioned in my first post, then you can take it from me that it is very much bigger than the system that you are referring to. Wind/solar that you refer to is only applicable to small units, regardless of efficiency - most modern cruisers rely primarily on diesel as that is currently the cheapest means of generation for any boat.

Not sure why your reference to the Danfoss units refutes what I was saying in my second post as you seem to be saying the same thing as I said. Unless you know the AHr drawn per day (ie run time and amps drawn during run) you cannot compare refrig units for efficiency.

In the end, striving for maximum efficiency is only an exercise worth while for severely energy constrained boats, that is not the case for most cruisers these days and having any duration (well at least not the ones I see). As I said, the unit Will refers to may actually be junk, but would be interesting to know more about it.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[Talbot]

Re: Compressors

From previous posts on other threads in this forum, I had assumed that your own installation was indeed much bigger than was being discussed, however, I was trying to give appropriate info for others as well, after all this discussion started with talk about power requirements for a 100 litre fridge, and throughout I have been trying to provide information against size. after all, it is pointless talking about efficiency of these devices without some data on their size.

If I have given you offfence I can asure you it was not intentional

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[Ships_Cat]

Re: Compressors

No, no offence at all Mark. Just trying to clarify the situation.

Looking at Will's post again, I wonder also if it is a freezer as could be saying gets to -15 C in 3 hours. Unclear as is an unfortunate line break right between the "-" and the "15".

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[ccscott49]

I run 2 fridges and a mains type freezer (through inverter) and dont use 200a/hr/day, I use 200ah for total boat systems a day. We are quite power hungry, but what the hell! Solar and wind are just not man enough and cost an arrm and a leg to buy in the first place, I would need about 180wattts at 24 volts, just to keep up, thats 6 x 60 watt panels, they arent cheap! If I get another boat, I will fit different systems, water cooled and built in with lots of insulation, top loading. With holding plates.

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[Ships_Cat]

Yes, I have to concede that I do not know exactly how much we average per day. If lights, some computer, we probably do about 2.5 hours of engine running with charge tapering from initial approx 100 A at bulk charge. So probably total refrig load is less than 200 AHr, freezer by itself draws around 40A and runs for about 2 hours a day depending on condenser cooling seawater temperature, how much fish we put into it, etc - there again will hold over for several days if need be with no compressor run, or demand drops alot if we are only occasionally taking things out of it and not freezing anything down. Refrigerator probably uses more as is opened more frequently and things like drinks, etc regularly put into it to be chilled.

So is pretty hard to quantify but as you say, what the hell.

Have had quite some discussions on generation, especially with one boatbuilder in particular, and come to the same conclusion each time. Diesel is the cheapest way to generate. Sort of along the lines, for a sailboat until one gets to the stage of wanting to run high demand items like heaters, breadmakers, etc or the demand is not otherwise large then big alternator on the engine is best. Beyond that a seperate generator.

People say that in the alternator on the main engine case that puts the engine maintenance costs up but one can do an awful lot of maintenance for the cost of a complement of solar panels, wind generator, etc of comparable capacity. And similarly if one is not forced to a generator by the demand, one can do an awful lot of main engine maintenance for the cost of a generator (talking about sailboat sized engines, obviously may not apply to Englander sized ones).

We have a couple of 30 watt solar panels to maintain the batteries when the boat is unattended and although I have forgotten exactly how much they and their installation cost, it sure represented the equivalent of a hell of a lot of diesel.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[wagenaar]

Prove if this unit will function, when the ship is leaning. A sailboat may lean for quite some time in a similar way, when making passages.
As far as the insulation is concerned: if you have enough room for it, you could always add more insulation.

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[William_H]

Re: Compressors

Thanks for all the comments folks especially John. Yes there was a claim on the box that it would pull to -15degrees in 3 hours ie a freezer although if it were empty that is probably no great claim.
The unti looks like a large esky ie molded plastic hinged lid carry handles etc. the Engel brand is very popular in Oz mainly for vehicles. I had one myself for some years it was brilliant as a freezer (4.5 amps when running at about 33% duty cycle)but the compressor failed and repair costs were going to be something like 70% of replacement. They use a vibrating compressor not a rotating one like I think Danfoss. It is this history that makes me doubtful about the chinese fridge but the price is very tempting. I confess I wouldn't have it on the boat which doesn't have the power and my sailing is short races so ice is the best way. Anyway looking at the cost of domestic fridges the 12V fridges seems excessively expensive. I wondered when the chinese would get into it and I reckon these referred to are priced not on cost but as compared to Engel and if power tools are any indication the price could come down a lot further. I guess they won't hit UK till next summer so we might have some feedback by then. Thanks again will

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[johifo]

Just saw one of these in local auto parts accesories store for $A500 thats 200 quid to you folks in winter. It is described as "Great Gear " 12 volts 76 litre 100 watt 8.2 amp made in China. It appears to be compressor type with tubes formed in aluminium in the lining for evaporator and tubes in a vemtilated box at the end where there is a computer type fan. ( hard to see the compressor) It has a LED temp readout with up and down buttons for the thermostat. Box claims to -15degrees in 3 hours. Has anyone any experience of these things? it seems good at about half price of an Engel or simil;ar. Tghanks inanticipation will

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Hello. I was checking out a 2023 View the other day and reading the specs, noticed it has a 10 Cu Ft double door fridge. It comes with 2 Group 31 batteries and 200W of solar roof panels. My question is if I drive approximately 8 hrs a day, will the batteries be able to run the fridge until the next morning or roughly 16 hrs. I know there are so many factors involved such as outside temperature, inside temperature, but ballpark figuring would the batteries keep the fridge running. I’m used to the propane/electric fridge in our 22M.

 

[William_H]

Hello. I was checking out a 2023 View the other day and reading the specs, noticed it has a 10 Cu Ft double door fridge. It comes with 2 Group 31 batteries and 200W of solar roof panels. My question is if I drive approximately 8 hrs a day, will the batteries be able to run the fridge until the next morning or roughly 16 hrs. I know there are so many factors involved such as outside temperature, inside temperature, but ballpark figuring would the batteries keep the fridge running. I’m used to the propane/electric fridge in our 22M.

Oh hear looking at that post 19 years ago. How time flies.
I don't know anything about Group 21 batteries. ie AH capacity. I presume your driving 8 hrs a day would both run the fridge and charge the batteries. That leaves you with 16 hrs of running on batteries. (presumably not much from solar in that 16 hrs) Of course depending on ambient temp over night and temp set for fridge to maintain if fridge takes 8 amps when running it might well deplete batteries in that time. However assuming you have a low voltage cut out on fridge, this might not be a disaster as of course the fridge has an ability to store the cold. All you could do is try it out in real life.
Here in oz I think a fridge could go really well running off solar panels with no battery and just good insulation. But I have not seen a fridge so set up. ie you want a 12/24v compressor with no low voltage cut out. ol'will

 

[B27]

I'd suggest looking at the energy rating of a similar domestic fridge, which will tell you a kWh per year guideleine.
From that estimate the energy for 16 hours.
Then find out the capacity of the batteries.

Fridges vary a lot in their insulation.
Also someone designing a fridge for intermittent power might use a lot of eutectic plate capacity to 'store cold'. Then have two thermostats so the fridge gets colder while there is engine power and 'ticks over' when on batteries.

I have a small 'camping fridge', top opening which averages about an amp, so a modest battery will run it for 16 hrs no problem.