Battery weight?

[psneeld]

While solar is nice, after a decade of RVing, regular joe camper is not ordering some custom job...but uses propane refrigeration.

And I am pretty sure mine had no compressor...it used a propane flame or ac/dc heating element to do the ammonia cycle thing.

And your amp hour thing for danfoss compressors is unbelievable unless you have a super custom box built.

I have 2 danfoss fridges on my boat and 400 watts solar barely keeps up with normal day to day boating even on sunny days. Then there are clouds and trees. Sounds like more theory than any rving or boating experiences I have had.

10AH day? My danfosses use 4 to 5 amps running. So 2 to 2.5 hrs running all day?

Usually cycle times are 50 percent real world...you know, where people open them to eat and drink.....and even the best of the best would be happy with a 20 percent run time with no one opening the door. Not likely in my world.

[john61ct]

Originally Posted by psneeld

And I am pretty sure mine had no compressor...it used a propane flame or ac/dc heating element to do the ammonia cycle thing.

AKA absorption fridge.

Don't bother running on 12V unless there's an active charge source.

For the compressor fridges, no, I was talking OTS units, 7 min per hour runtime is pretty common in mild conditions, but of course lots of different factors involved.

Variable speed compressor helps.

Engels are very robust and pretty darn efficient.

[psneeld]

you have a link to an OTS unit, not familiar with the abbreviation?

I love researching quantum leap tech.

[psneeld]

found some real world amp hours for an engle 35 liter fridge...

and correct me if I am wrong please...but isnt 35 liters about 1.3 cu ft? That would make the engle about 1/5 to 1/7 the size of a regular rv or boat fridge for a liveaboard or rver that spends extensive time aboard but doesnt like roughing it with canned food and MREs.

summary

Day 1 Starting with a warm fridge on a 35 degree celcius day, I added twelve ‘cool’ 375ml cans of drink and 2kg of cold meat to the fridge. The fridge used a total of 43 Amp Hours in 24 hours.

Day 2 This was a 37 degree celcius day. I added 600grams of warm food, six warm cans of drink and a 750ml bottle of warm water. The fridge used 34 Amp Hours in 24 hours.

[BruceK]

Originally Posted by psneeld

you have a link to an OTS unit, not familiar with the abbreviation?

I love researching quantum leap tech. ii8

Could be "Outback Touring Solutions". I just found it by online searching, so others might too, Aussie site for outback travelers.
7 mins per hour fridge run time is remarkably low,from on water experience my 2 Danfoss compressors run more than that.

[psneeld]

as usual...there those of us using the stuff and those thumbing the catalogs and internet dreaming of the petfect setup.

then they get out there and those dreams unless funded with really deep pockets goes right down the shi**er...

[john61ct]

Originally Posted by psneeld

you have a link to an OTS unit, not familiar with the abbreviation?

I love researching quantum leap tech. ii8

Sorry, off the shelf, as in familiar, readily available in the market, mass produced, as opposed to DIY, custom or obscure

[john61ct]

Yes OTS portable units are of course smaller than RV or apartment style.

But increasing space capacity same time as better / thicker insulation can keep electric consumption constant.

I've seen people convert dorm style fridges with inverter and DC thermostat, claimed 25-40AH per day depending on conditions, replacement cost only $150-200.

Obviously adding room temp goods to any fridge results in at least 12 hours of unusual usage stats getting back to target temp. The lower consumption figures apply to maintaining a stable range.

Danfoss hasn't existed for many years, Secop bought them out, now made in China.

Waeco / Dometic dominates the low end, think they make their own, similar tech, also makes Adler/Barbour.

Engels uses an apparently very different type of compressor, Sawafuji. Also Norcold?

[psneeld]

More research is turning up that combo fridge/freezers usually have a higher cycle time than fridges only and 2 door versus one door tend to run more.

So I guess a tiny, fridge only could possibly only run a tiny bit...but again...it is not anywhere near my world of reality.

My world DOES involve adding warm beverages and recently cooked food to a fridge nearly every day.....its NOT an unusual activity that unecessarily ruins lab data for some fridge tester. So I severely doubt your gustimates of daily amp hours as well as the manufacturers "lab results".

I am not trying to be a survivalist with limited energy consumption using the best batteries money can buy.....I doubt many here are.

[Lou_tribal]

Speaking about fridge, anybody has experience with these:
http://uniqueoffgrid.com/product/por...er-120-litres/

L

[FlyWright]

Originally Posted by john61ct

Yes OTS portable units are of course smaller than RV or apartment style.

But increasing space capacity same time as better / thicker insulation can keep electric consumption constant.

Obviously adding room temp goods to any fridge results in at least 12 hours of unusual usage stats getting back to target temp. The lower consumption figures apply to maintaining a stable range.

Danfoss hasn't existed for many years, Secop bought them out, now made in China.

Waeco / Dometic dominates the low end, think they make their own, similar tech, also makes Adler/Barbour.

Engels uses an apparently very different type of compressor, Sawafuji. Also Norcold?

Most of us who own trawlers do so because we want to be comfortable on the water with others aboard. A micro RV fridge with the capacity of a home depot bucket is of little interest except for the trailer boats among us. The numbers you put up are probably only achievable by those in trawlers with the blowboater mentality to power consumption. Us "real" Trawlermen like to use the comforts God gave us for our boating pleasure.

Originally Posted by john61ct

I've seen people convert dorm style fridges with inverter and DC thermostat, claimed 25-40AH per day depending on conditions, replacement cost only $150-200.

Do you have links to a DC thermostat you'd recommend? Maybe even a tutorial on how you did it? I'd be interested in converting my defrosting 110V 3.1 cu ft fridge which is a battery pig at over 100AH/day.

[sunchaser]

Originally Posted by psneeld

My world DOES involve adding warm beverages and recently cooked food to a fridge nearly every day.....its NOT an unusual activity that unecessarily ruins lab data for some fridge tester. .

Yes, some indeed use these contraptions for their intended purpose. A well used decent sized two door unit with Danfoss like mine uses about 10 amps/hour by BMK gauge when running. The run time is highly variable as you note.

[john61ct]

No but looks good to me.

33 W, 2.7A @ 12V DC

38 Ah/24 hrs (Lrg. Side set to +5⁰C/ Sm. Side set to -13⁰C in a 25⁰C ambient)

is pretty good, obviously freezers burn a lot more amps, I think average 4x a fridge-only unit.

Haven't really come across reports of blatantly bad products in this category (portable 12V compressor fridges), just that Engel users rave about theirs taking a beating for many years.

[john61ct]

Originally Posted by FlyWright

Do you have links to a DC thermostat you'd recommend? Maybe even a tutorial on how you did it? I'd be interested in converting my defrosting 110V 3.1 cu ft fridge which is a battery pig at over 100AH/day.

The point of the DC thermostat is to keep both the inverter and mains-power compressor off most of the time, only the thermostat is running 24x7.

Pretty sure it was nothing special, eBay-Chinese cheapy.

Wasn't me done it (yet), just seen some HowTo threads in land-based forums, will look out for them to post a link.

You def need to start out with a fridge with an efficient energy rating, which tends to be rare among shore-power fridges.

And finally yes, I try when living off-grid (as opposed to travelling) to only burn fuel a few hours a week, so am more conservative in all my energy consumption than most here.

[AusCan]

Originally Posted by Lou_tribal

Speaking about fridge, anybody has experience with these:
Unique Off Grid

L

No experience, but I like the design with separate controls on fridge and freezer.

Mine Engel is fridge or freezer. On long trips requiring lots of food and beerI use it as a freezer to make ice for the large built in cockpit cooler.

My house bank consists of 3 x 120 Ahr 12V chinese AGM batteries, with no solar (except a folding 100 watt emergency panel that I never use), a 120 amp alternator, and a 20 amp mains charger. I find it more than adequate for 3+ days on the hook. It may be good for a week, but I usually cruise around a bit every few days so I haven't checked the limits. So far I have never dropped below 12.5 volts. I don't even bother to plug in at a marina if I plan on leaving within a few days and running the engine.

My electricity use is less than most TF members, (just the fridge, lights, phone & laptop chargers, water pump and air compressor) but I don't have a smart meter so I can't tell you how much I use.

[john61ct]

Originally Posted by sunchaser

uses about 10 amps/hour by BMK gauge when running. The run time is highly variable as you note.

Sorry to nitpick, but wanted to clarify units.

I think you mean it uses 10A while running. "Amps per hour" is at best unclear, as "at 10 amps for two hours" equals 20AH.

So if conditions require it to run 30% of the time, that fridge would consume 72AH per 24 hours.

[BruceK]

Originally Posted by john61ct

.
Danfoss hasn't existed for many years, Secop bought them out, now made in China.

How "many years"? Takeover agreement signed 2010?
Certainly not long enough for there to be no Danfoss made units in operation and for the many users to be able to confidently report on their "real world" performance. One of mine is 9 years old, the other was fitted new in 1981 with the boat,both still perform well.
What has been your experience operating Danfoss powered fridges on a boat?

[BruceK]

Originally Posted by Lou_tribal

Speaking about fridge, anybody has experience with these:
Unique Off Grid

L

Lou, the plus is the 2 compartments, it can be fridge and freezer, whereas with smaller versions you choose one or other function. I recently saw Dometic/Waeco units advertised here with 2 compartments. Tend to think you may be better off with a known brand, maybe that one is known over there. The "no name" brands selling cheap here on ebay etc seem not to do so well, that`s just according to user reviews. My portable Waeco is still good after 9+ years.
An advantage of portable units(120L is getting big) is the ability to pull it down cold at home on mains, plug it into 12v in the car, and load it cold onto the boat, then using your choice of electricity.

[AusCan]

Originally Posted by FlyWright

The numbers you put up are probably only achievable by those in trawlers with the blowboater mentality to power consumption. Us "real" Trawlermen like to use the comforts God gave us for our boating pleasure.

You've uncovered my facade. I admit to having the blowboater mentality. I'm not a real trawlerman.
Or maybe I'm just waiting for God to give me one of those power hungry boats with an electric stove, dishwasher, microwave, auto-flush toilets, and underwater strobe lights.

It wasn't under the Christmas tree.

[FF]

SIZE MATTERS, in order to have low consumption the unit must be very well insulated.

On a boat of limited volume many seem reluctant to build a reefer with 4 inches of insulation, or even wrap a production unit with loads of external insulation.

The vacuum side wall insulation is interesting , but seems failure prone.

A really efficient variable speed DC compressor is only half the issue , what it has to cool is the other half.

For the big guys with lots of volume Sunfrost might be an answer.

My personal answer is Propane and to heck with making/storing 200A a day.