Why no Residential Fridges?

[newhaul]

Originally Posted by travellerw

Yes I know we were going back and forth on the same thing.. Dispelling the myth of "far cry", but I thought it only fair to use real numbers.

I understand the difference between Wh and Watts.. I used them interchangably as it was clear in the context of the sentence what I was talking about!

Now now " far cry" is a video game my boys love to play
https://en.m.wikipedia.org/wiki/Far_Cry_4

[nebster]

Originally Posted by newhaul

If you want to get real world numbers on the cool blue system just look on here and on sailnet under my name to find the info I wrote a rather lengthly series of posts on the power draw at various water and air temperatures suffice to say have been keeping ice cream solid since February with 200 watts solar to run the whole boat no shore power or engine charging 2.5 cf top freezer and 7 cf fridge lower front load liveaboard.

Hmm, now that sounds like interesting data. If you achieved efficiency similar to a house fridge, you'd be looking at 65Wh * 9.5cuft = ~600Wh per day. That does seem within the realm of reason for 200W of solar in a reasonably sunny unshaded locale.

If you're getting even better actual energy demands from your fridge, that'd be great to know. You've posted so many posts that it got too tedious to go try to find your old notes. Let us know if you can link us up!

[SV THIRD DAY]

Originally Posted by newhaul

If you want to get real world numbers on the cool blue system just look on here and on sailnet under my name to find the info I wrote a rather lengthly series of posts on the power draw at various water and air temperatures suffice to say have been keeping ice cream solid since February with 200 watts solar to run the whole boat no shore power or engine charging 2.5 cf top freezer and 7 cf fridge lower front load liveaboard.

Thanks amigo, but just to avid confusion the data in this thread isn't talking about the CoolBlue systems but rather the 120v to 12v Dorm box conversions. Kinda of an apples/oranges product. But I love your Hard Ice Cream comment....

[sailorchic34]

Originally Posted by StuM

My comment re SC's posts above is apropos. No one who truly understands the difference would use them interchangeably (sp!).

LOL, I live with amp hours every single day.

[nebster]

Originally Posted by SV THIRD DAY

Thanks amigo, but just to avid confusion the data in this thread isn't talking about the CoolBlue systems but rather the 120v to 12v Dorm box conversions. Kinda of an apples/oranges product. But I love your Hard Ice Cream comment....

I just looked up the coolblue data on your site. Looks like you're getting 40Wh/cuft, which is impressive. I don't know what testing mechanism energystar uses for their data, but if the methodology is similar, that's about a 33% performance gain over a residential fridge. (The very best fridges in the energystar test achieve similar Wh/cuft, but they might be unusual or expensive or repair-prone, so I was hesitant to use them.)

[newhaul]

Originally Posted by SV THIRD DAY

Thanks amigo, but just to avid confusion the data in this thread isn't talking about the CoolBlue systems but rather the 120v to 12v Dorm box conversions. Kinda of an apples/oranges product. But I love your Hard Ice Cream comment....

True I have a cool blue off the shelf holding plate system it is however a front loading system not top loading like most of the holding plate systems. The compressor has to run to freeze the plate in the same temperature conditions. So closer to oranges and Mandarin oranges than apples:

[sailorchic34]

Originally Posted by StuM

No such thing as "amps per day"

Someone who does a bit O'engineering should at least know the difference between Amps and Amp hours.

Hum amp/hr and amps per day, perhaps read as amp/day. Both a measure of amps stored or used over a given reference time frame. Gee there is also amp/seconds.

From a cruising standpoint, living on a boat, I find it useful to look at the 12V system on a 24 hour day standpoint. That's why my fridge that draws 15 amps when running, only uses 2.5 amp/hr or about 55 amp/hr per day with daytime cabin temperature highs in the 90's and night time lows in the 70's.

Most appliances are tested at 70 degrees which is fine when you live on land. Alas I live on a boat where indoor cabin temperatures are sometimes 70, sometimes 40 brrr, and sometimes 105 degrees F. I try to avoid many of the latter.

So on a boat you have to deal with higher cabin temperatures with corresponding longer compressor run times and higher amp/hr loads.

[StuM]

I know I'm a pedantic old fart, but this misuse of units really grates with me.

It's not Amp/hr or Amp/day (the slash is a "divide" sign) . It's Amp Hours or Amp Hrs/Day. If you are pulling 4 Amps for 2 hours you use 4 x 2 = 8 Amp Hrs. Not 4/2 =2 Amp/hrs.

Edit: And you can't "store Amps" An Amp is the basic SI unit of current flow

[nebster]

As long as we're digressing into pedantry, there's another problem with Ah: it's only really useful if you live primarily or exclusively in a 12V world.

Not so, for me. Computing devices mostly use 5V. 12V bus on the RV. 24V bus on a big boat. 36V and 48V on my electric bike batteries. 60V on my solar strings. 120V from inverter and shore. (240V if we're traveling overseas in a cruiser!)

So Ah is pretty awkward, and I find it easier to think in Wh to be able to make comparisons and reason about energy usage.

[AbenF]

I'm going to parrot some of what's been said already, but I'll add some highly opinionated thoughts from someone in the trade:

On the propane issue, while I have seen them in the past on one or two boats, they seem to be very rare. Also, they are slowly losing favor among RV-ers as solar is becoming more popular. The main complaint I hear is failure to cool adequately. Plus, there aren't any that I know of that are up to the marine environment.

On domestic units, apparently some will handle heeling, but many won't. And again, they tend to rust. Auto defrost will kill your batteries in a hurry, too, not to mention the problem with where the drips are going to go (yes in the pan, but that spills underway). If you look at a marine fridge and a kitchen one (not a dorm-size), you'll note that the domestic doors are usually a lot thicker and heavier. And how will it mount - marine units have flanges. Latching - bungee cords or ??? So the bottom line is that they are a good match for large trawlers, but not so much anything that will pound or heel.

Water cooling is somewhat popular on sailboats - maybe 5% or less on all-electric systems except for Florida and the tropics, and nearly all engine-driven (more about that in a minute). For the electric ones, while it is true that water absorbs heat more effectively than air, as noted earlier, it's a lot easier to move air than water. With pumped water systems, the pumps are noisy, power-hungry, and a frequent (and expensive) failure point. With thru-hull and keel coolers, keeping them clean is a constant task, and they work best when the boat is moving. But the real key, for me anyway, is that cruisers coming back from the tropics seem to be pretty happy with their air-cooled systems. So you have affordable, user-installable systems that use little power, are quiet, and last 16-20 years. What's not to like?

Speaking of air, the sailboat kits need remarkably little air in temperate areas, but in the tropics the trick is to mount the condenser package in a well-ventilated area, in a lazarette with a vent if possible. Conventional 'fridges (ie: with doors) usually vent to the rear and need some air flow back there, but a number of models vent to the front. Vitrifrigo makes conventional units that have remote condenser units that can be placed where convenient.

Engine driven 'fridges on recreational boats are also a thing of the past, in my opinion. Why run your engine for an hour when you could add another solar panel? And they're expensive and a maintenance nightmare. They made sense 20-30 years ago, but I haven't found anyone who had one and wanted another. The one component they had that I like is the holdover plate. Most of the modern units use evaporator plates and cycle throughout the day, but if you have solar you can schedule the system to only run while the panels are putting out, and put less stress on your batteries overnight. For a price, of course. On the other hand, with about 40AH per day, it's not that big a deal.

[travellerw]

Originally Posted by newhaul

If you want to get real world numbers on the cool blue system just look on here and on sailnet under my name to find the info I wrote a rather lengthly series of posts on the power draw at various water and air temperatures suffice to say have been keeping ice cream solid since February with 200 watts solar to run the whole boat no shore power or engine charging 2.5 cf top freezer and 7 cf fridge lower front load liveaboard.

Impressive numbers... Including the price...

Doing a quick math exercise based on the price of solar panels, its a better value to install more panels and a less efficient system. Of course my opinion might be skewed on a cat that has plenty of room for panels.

[No Mondays]

Our sailboat spends most of its time at the dock with shore power. When we live aboard for a week or two we need more refrigeration space. We use the typical top-loading fridge that came with the boat but also use a under-counter fridge for drinks and such. When we sail for a couple of hours the drinks are still cool and so much easier to get at. And these small fridges can be had for less than $100 (because they don't say Marine on them).

[skipgundlach]

Originally Posted by newhaul

If you want to get real world numbers on the cool blue system just look on here and on sailnet under my name to find the info I wrote a rather lengthly series of posts on the power draw at various water and air temperatures suffice to say have been keeping ice cream solid since February with 200 watts solar to run the whole boat no shore power or engine charging 2.5 cf top freezer and 7 cf fridge lower front load liveaboard.

That is simply stunning.

After much wailing and gnashing of teeth, on a system with very effective insulation as proven with delta testing and the most recent defrost taking 3 full days to have the freezer insulation warm enough to not sweat, with the doors OPEN, and the plates dry/warm, in 80+ weather, I've concluded that what I have is what I have, and there's nothing I can do about it besides move to ME where the water might not grow junk quite so fast, and be 40-50F for the water cooled portion/hull temps and the air rarely above 80F.

However, in our real-life, on 80+ water, in 80+ air, ~3.5/7CF freezer/reefer, on average, at night, no wind, no solar, we use 10A continuously in our auto-set smart controller Sea Frost system which keeps the freezer at about 5-8 degrees warmer than I'd really like, and the reefer where we want it.

Sometimes, there's enough KISS wind and 370W sun input that I can go more than two days before I'm forced to replenish the more-than-250AH deficit. Overnight, with no wind and no solar gain to heat nor contribution to ambient temps, we will, like clockwork, eat 10A per hour; if it's at -20CAH when we go to bed, it will be at least -100CAH when we get up.

We are niggardly with our openings of our front-load reefer, and extremely rarely open our top-load freezer. Yet, I imagine our daily load exceeds 240AH using an air and water cooling SeaFrost system.

During the times when we have to take the pump offline (it broke, or the intake system is so clogged as to make the water worthless, and we have to take it entirely apart to clean it out), the air cooling runs continuously, and never cycles, as the freezer temp slowly climbs.

I applaud those who seem to have the essentially identical circumstances as we, and get by on well under 100, and sometimes half THAT, AH/day. The Honda generator is the bane of my admiral's existence...

[sailorchic34]

Originally Posted by StuM

I know I'm a pedantic old fart, but this misuse of units really grates with me.

It's not Amp/hr or Amp/day (the slash is a "divide" sign) . It's Amp Hours or Amp Hrs/Day. If you are pulling 4 Amps for 2 hours you use 4 x 2 = 8 Amp Hrs. Not 4/2 =2 Amp/hrs.

Edit: And you can't "store Amps" An Amp is the basic SI unit of current flow

Stu, why are you trying to teach me things about amp/hr or amp-hr, Ah or amp hr, I learned when I was 13. Believe it or not, I actually know how to multiply and subtract amps. My HP50G calculator has those keys on it.

I was not using the hash mark as a divide symbol. It, that hash mark, is sometimes used as other then a divide symbol in the engineering world. Many engineering texts don't even use the hash mark as a divide symbol. shocking I know.

I am guilty of using amps and amp hr interchangeable, which I think most of the folks understood. But then I live in a 12V world and live on batteries and solar with a 120V fridge and a $50 inverter.

[Mystic38]

by all means use Whr if that pleases you, but dont expect everyone to follow your lead

If your boat has 12V batteries then everything is related to that.. so the use of Ahr is highly relevant

it is irrelevant to me that my laptop runs off 18.4V, it is irrelevant that my phone charges from 5V and it is also irrelevant that my Solar panel gives out about 20V..it is also irrelevant that my 120V ac TV runs off a small inverter, or that my 800W microwave runs off a large inverter.

What is critically relevant is the daily consumption amounts and charging amounts related to my one and only power source... the same power source as probably 99% of sailboats.. 12V

Originally Posted by nebster

As long as we're digressing into pedantry, there's another problem with Ah: it's only really useful if you live primarily or exclusively in a 12V world.

Not so, for me. Computing devices mostly use 5V. 12V bus on the RV. 24V bus on a big boat. 36V and 48V on my electric bike batteries. 60V on my solar strings. 120V from inverter and shore. (240V if we're traveling overseas in a cruiser!)

So Ah is pretty awkward, and I find it easier to think in Wh to be able to make comparisons and reason about energy usage.