Another reason why Eutectic Plates are less desirable than Standard Refrigerator

[daletournier]

Originally Posted by john61ct

Yes, personally I don't need convincing either way.

I want to settle the above specific question For Science.

Me personally, I don't care about the science, I just want cold stuff to stay cold by using excess electricity I can't use elsewhere. That's seems efficient to me.

[TJ D]

Originally Posted by daletournier

Me personally, I don't care about the science, I just want cold stuff to stay cold by using excess electricity I can't use elsewhere. That's seems efficient to me.

I think that almost all cruisers are in this same camp.

And for me, the bottom line is that I'm using a lot more battery to have a warmer freezer now than I did before. I just can't get it cold enough with the little Danfoss compressor that's in my current unit during times of excess power generation, from whatever source.

The fridge is about the same, though.

I'm absolutely convinced that for a cruising boat spending a lot of time at anchor, particularly one which will be using the main engine/generator for other purposes regularly (doesn't this include almost all of us?) will be much better off with a high-capacity holding plate system, particularly in the freezing department.

It's pretty cool to see it get super cold and not turn on again all day.

I would say that, on average, I was EFFECTIVELY using about 30-40ah/day with the holding plate freezer (considering engine use) and that's now probably doubled or even tripled with the evaporator system with the same engine use profile. It just doesn't get cold quickly while there's excess power.

That, friends is a pretty big deal in the power department.

I'm kicking myself for having ever switched. I bought into a sales pitch and a lower price, and I really wish I hadn't.

[daletournier]

On my last boat I had a evaporator system and then went to eutectic (Oze fridge). I had a small battery bank the eutectic made a very big real world difference as I had excess solar.

My current boat came with a evaporator system, it works fine and I have a bigger battery bank so no real problem except for the no sun days BUT I still would prefer my old eutectic system for above mentioned reasons. I just don't like hearing it going off and on many times during the night knowing nothings going back into the batteries when I know a good eutectic system will make it through most of the night.

[daletournier]

Also i suppose this is when the Lifepo advocates can say they waste no excess power as their batteries will take most of whats generated, or until they can take no more, the eutectic advantage becomes less important?

[Richard Kollmann]

Originally Posted by TJ D

I mourn the day I replaced my holding plate system with standard evaporators. Worst thing I ever did on my domestic systems.

Here's why- and why this isn't discussed more is really a mystery to me.

At anchor or underway with the holding plate system, I would run the engine for an hour or 90 minutes in the morning-charge batteries, make water, etc.

During that time, my system would draw 40 amps or so (the alternator could easily pick up the load with no reduction in battery charging), and the freezer would get cold as hell, around 0 to +5F on average. During longer runs, it would get down to as low as -10f.

And then the thing would shut off and not run again for many, many hours.

In real-life amp hour use terms, this cost me nothing. The fridge would kick on and off through the day for a few minutes, but the big eater of power was taking very little from the actual energy budget with daily engine use.

Fast forward to today-I've got 2 evaporator systems installed, and while they're lower draw, the damned things run a hell of a lot. So, I've got this semi-continuous drain going on 24/7. My batteries are discharging at a much higher real rate than they ever did with the Eutetic system.

I suppose if I added a few hundred more watts of solar (currently 400), it would bother me less, but on cloudy days, I'm watching things drain at a much higher rate than I like.

This is the real advantage of a holding plate system. You can put a lot of BTU's in the bank when you've got an excess of power, whether from the engine, the dock (I would often run my freezer WAY down on shorepower before heading to anchor again), or alternatives.

So, while I'm not interested in getting geeky about it, I'd take a holding plate system any day of the week. When my current systems come out, I'll be switching back, 100%

No disrespect to evaporator proponents, just one guy's experience.

TJD, You did make a big mistake by removing an engine driven surplus energy compressor a true large eutectic holding plate system and then installing a small 12 volt system. The 12 volt with either a standard evaporator or cycling eutectic plate the end results are the same because small 12 volt compressors produce no surplus energy. Energy in equals energy out unless you want to be creative. For the inconvenience and costs of eutectic plates to be of value you need alternative electrical energy other than engine alternator.

[Attikos]

I tried a eutectic plate but discovered that in a rough sea it won't hold my chili any better than a piece of Corelle.

[john61ct]

Originally Posted by daletournier

Also i suppose this is when the Lifepo advocates can say they waste no excess power as their batteries will take most of whats generated, or until they can take no more, the eutectic advantage becomes less important?

Only if your LFP bank is sized so large as to capture all/most the excess/free power.

Lots more likely for smaller usage solar-only scenarios.

The fact that the LFP is lighter means you can carry more.

But so much more expensive per AH, the added price of the holding plates is likely to be more relatively affordable.

Those with lots of AH / day usage, plus high dino juice charging amps available on demand, then the questions are

are you burning fuel for hours for other reasons anyway? Or

are you living on the hook trying to run it as infrequently as possible?

Lots of variables.

[john61ct]

Originally Posted by Richard Kollmann

because small 12 volt compressors produce no surplus energy. Energy in equals energy out unless you want to be creative.

Please explain this in more detail.

To me, compressors produce no energy at all, they are consumer loads only.

The excess/free energy that holding plate designs capitalize on, comes from charge sources like solar, genny or alternators.

Are you saying the 12V compressor is not powerful enough to charge the holding plates fast enough?

> For the inconvenience and costs of eutectic plates to be of value you need alternative electrical energy other than engine alternator.

A large-frame 200+A alt that happens to be running 4+ hours a day anyway can be that source just as effectively as any other, especially into a lead bank.

[newhaul]

Originally Posted by john61ct

Only if your LFP bank is sized so large as to capture all/most the excess/free power.

Lots more likely for smaller usage solar-only scenarios.

The fact that the LFP is lighter means you can carry more.

But so much more expensive per AH, the added price of the holding plates is likely to be more relatively affordable.

Those with lots of AH / day usage, plus high dino juice charging amps available on demand, then the questions are

are you burning fuel for hours for other reasons anyway? Or

are you living on the hook trying to run it as infrequently as possible?

Lots of variables.

ok since it was brought up I am switching to Lfp so I don't have to carry as much battery to run the boat. To have a 3 day buffer I need 150ah available. I can get 2 100ah Lfp that will do the job or I have to carry 440an of any other matrix of battery to have the capacity. ( due to deeper cycle profiles) now with eutectic plate fridge I can do that due to 400 watts solar and same in wind. With evaporator type of unit I would need to double my Lfp or carry the weight of 440ah in Fla. So holding plates make the most sense for my boat.

[OzePete]

Originally Posted by john61ct

Great info!

I think we have a consensus here that

where free / excess energy is available on a regular basis, **and** the fridge is in use for weeks at a time

eutectic holding plate systems reduce / replace the need for battery storage

and thus are superior strictly from an energy-efficiency POV.

The controversy is in the comparison of energy efficiency with thin-plate evaporative systems once that free/excess energy factor has been taken out of the equation.

And I would really like to see us make evidence-based progress toward either confirming Pete's test results, or modifying the framing conditions of those tests to be "more fair/realistic", whatever, but get away from distracting sniping and see if we can stick to objectivity.

Good points John.
Regards: http://www.cruisersforum.com/forums/...se-200041.html
Sadly after providing the very detailed and well reported trial (Link above) we had performed for our in-house information, it is obvious that the key issues raised are not understood. An understanding of the two key reasons why there were significant power efficiency differences, would make it clearer as to why the results were so extreme.

Sadly also, that having provided a great deal of detail, explanation, pictures etc, some here choose to attempt to discredit the test yet not once have any of them provided any data, trial results or pictures and none have provided any direct relevant rebuttal to the 9 points listed, instead we have all sorts of waffle in an attempt to divert the topic.

Regards the two key efficiency issues: (They really are quite simple to understand)
A: The first is COP (Co-Efficiency) This is simply a figure that relates how much heat is removed by a refrigeration system for each watt of electrical energy consumed. We all understand that a car that does 30MPG @ 60MPH is far more efficient than one that does 20MPG. Now similarly a refrigeration system that is rated at COP 1.95 (eutectic) is removing heat far more efficiently than one rated at COP 1.13. (Cyclic)
It is as simple as that and this fact is indisputable, period.

B: The second issue was the number of compressor start ups per day from each system type tested. We all know that any equipment going from stopped to full speed wastes energy albeit difficult to calculate and therefore a major reason for the test.
During the test the Eutectic system only averaged 1.5 of these wasteful startups per day while the cyclic system started about 40 times per day.
Again it should be easy to understand why the cyclic system was far less efficient.

Now having again attempted to get this discussion back to the core issues, please be assured that we stand by the trial report and its findings as clearly described, and also as stated welcome anyone or their agent to inspect our test equipment and methodology.

I would welcome anyone to study the report and dispute anything point by point that they can evidence as being incorrect, but please do this with data that supports your claims and not just another waffle on from someone who doesn't like being proved wrong.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[Richard Kollmann]

Originally Posted by john61ct

Please explain this in more detail.

To me, compressors produce no energy at all, they are consumer loads only.

The excess/free energy that holding plate designs capitalize on, comes from charge sources like solar, genny or alternators.

Are you saying the 12V compressor is not powerful enough to charge the holding plates fast enough?

> For the inconvenience and costs of eutectic plates to be of value you need alternative electrical energy other than engine alternator.

A large-frame 200+A alt that happens to be running 4+ hours a day anyway can be that source just as effectively as any other, especially into a lead bank.

I can only stay with you when you follow TJD,s topic problem. Sure you can be creative with 200 amp-hr alternator and house battery bank of 2,000 amp-hrs but stick to TJD's facts provided. He was satisfied with a large engine driven holding plate system producing anywhere from 4,000 to 12,000 Btu per hour and not satisfied with a 300 to 500 Btu 12 volt refrigeration unit. If he bought Pete's or Rich's eutectic plate 12 volt units he would still be disappointed.

Too bad we cannot hold the boat refrigeration sales person to an insurance performance bond agreement. If it does not live up to the agreement bank will not release the purchase price to seller.

[SailRedemption]

I don't think he had a engine driven compressor, he just ran his 12v compressor when he was charging batteries. Effectively freezing the cold plate for "free".

[newhaul]

Originally Posted by Richard Kollmann

I can only stay with you when you follow TJD,s topic problem. Sure you can be creative with 200 amp-hr alternator and house battery bank of 2,000 amp-hrs but stick to TJD's facts provided. He was satisfied with a large engine driven holding plate system producing anywhere from 4,000 to 12,000 Btu per hour and not satisfied with a 300 to 500 Btu 12 volt refrigeration unit. If he bought Pete's or Rich's eutectic plate 12 volt units he would still be disappointed.

Too bad we cannot hold the boat refrigeration sales person to an insurance performance bond agreement. If it does not live up to the agreement bank will not release the purchase price to seller.

please quit dodging the questions . For me from a real world usage I would take holding plates over evaporator any day. On a boat there is always something making power.
Be it engine, generator, solar, or wind. ( almost forgot hydro). Once batteries are full that's when the holding plates will show how much better they are than evaporator systems.

[Richard Kollmann]

Originally Posted by SailRedemption

I don't think he had a engine driven compressor, he just ran his 12v compressor when he was charging batteries. Effectively freezing the cold plate for "free".

SailRedunption, you may be right a very large 12 volt compressor drawing 40 amps for 90 minutes daily would not be an engine driven compressor.

Electrical energy is not free unless it comes from wind, solar, and water generators.

[Copacabana]

I imagine it also comes down to your battery bank size and charging means. In my case, with a small 220AH bank and 355w of solar power, the evaporator fridge seems a good fit, as it draws a small amount of power over the day, which is supplied by my solar panels. I often turn my fridge off at night. I don't think I could provide 40 amps for 90 minutes or more every day. While my solar panels are running the fridge, they also charge the battery bank. At the end of the day I've got my fridge near 0 degrees and the batteries fully charged.