Refigeration Amp Hour usage survey

[Mike OReilly]

We are averaging about 180 ah on a modest sized fridge/freezer. This is way more than it should be b/c I can't get my unit to go into resting mode. It's always running full throttle at about 7 amps.

... I'm trying to figure out why. Luckily my solar and wind can pretty much keep up with the draw.


Why go fast, when you can go slow

[skipgundlach]

Originally Posted by typhoon

Did you do an Ice melt test? Before I put my evaporator plate in my box I put a bag of Ice in a bucket and set it inside the room temperature box . It took over two days to melt just about 50 hours with the temperature outside the boat averaging in the high 70s .

Im just throwing stuff at you , I wonder if you are getting thermal bridging in your insulation with all that epoxy.

Tell me how big your boxes are again ? I have a 7.7 cubic foot box , just a fridge , freezer is a separate cabinet with its owns system. I have yet to reno that yet and I am not using it .

Do you remember your pressures the last time you had your gauges on ?

Regards

I haven't done an ice melt - because I can't figure out the cat (Shroedinger's) and Heisenberg - any time I'd attempt to measure it, I'd muck with the temperature and add an unknown amount of BTU.

However, the doors and sides and tops are nominally the same temperature as ambient, so I don't think I'm losing any cold/gaining any heat via conduction

My boxes are ~3.5/6.5 freezer/reefer; reefer is supplied via fan-fed spillover controlled with an electronic thermostat.

I have never had gauges on this system; only the original Frigoboat - the installer had it finished by the time I returned, so I had no opportunity for pictures or recording info. However, as above, I think he was competent.

OTOH, there is either a constant stream of bubbles, or the liquid is well under the sight glass (you can see it flowing, so sometimes no turbulence in the 'river'), which seems to me to be undercharged. Yet, with all that volume, and a constant pressure valve (low side should read a constant 4PSI regardless of what else), it seems that perhaps the amount of gas isn't significant. Certainly, Cleave wanted me to do other tests before I hooked up; it was those which led to my recordings of AH consumption...

HTH

L8R

Skip

[skipgundlach]

Originally Posted by Mike OReilly

We are averaging about 180 ah on a modest sized fridge/freezer. This is way more than it should be b/c I can't get my unit to go into resting mode. It's always running full throttle at about 7 amps.

... I'm trying to figure out why. Luckily my solar and wind can pretty much keep up with the draw.


Why go fast, when you can go slow

You must have a massive solar array and a heck of a wind machine; I have no clue, actually, how much the rest of our boat uses, but I'm sure we don't generate 180AH/day in other than tropical summer sun and eastern caribbean winds (constant 15-20) - though, as mentioned, in the Bahamas in the summer, if the wind is blowing and the skies are clear, sometimes we can stretch the period between Honda runs to as much as 5 days (we run when we get down 200AH or more)...

One of my next projects is trade out my 370W for 870W. That MAY allow us some freedom from the roar of the 2000i...

L8R

Skip

[skipmac]

Originally Posted by Mike OReilly

We are averaging about 180 ah on a modest sized fridge/freezer. This is way more than it should be b/c I can't get my unit to go into resting mode. It's always running full throttle at about 7 amps.

... I'm trying to figure out why. Luckily my solar and wind can pretty much keep up with the draw.


Why go fast, when you can go slow

Boy Mike, that's a heap of compressor running. I would think running that much would turn the whole box into a subzero freezer. What kind of temps are you seeing? If it's staying close to your set temps then maybe the compressor is having to run that much to keep it cool. How's the insulation and seals?

[Frugal]

Interesting thread.
I run a Danfoss BD50F frigiboat system into a dual compartment top loading fridge. The unit is ducted air cooled sucking air out of the bilge.
The main compartment with the evaporator plate runs at just having permanent ice on the plate. The second section with a spill over connection runs at about 10 deg Celsius for the perishables.
The unit has a 4 speed adjustment switch allowing 2000 to 3500 rpm.
Cruising in a no jumper climate I set the RPM at 3500 and used an average of 134.8 A/H per day over 2 years. There was a constant overheating problem and additional cooling fans made little difference.
On resetting the speed to the slowest 2000 rpm the average daily consumption over the last 4 years has been 49.1 A/H per day and the compressor temperature is within 10 deg C of ambient.
At 2000 rpm the load when running is around 5 amps so cycle times are about 40% 0n.

The compressor speed has a diabolical effect on consumption

[Mike OReilly]

Originally Posted by skipmac

Boy Mike, that's a heap of compressor running. I would think running that much would turn the whole box into a subzero freezer. What kind of temps are you seeing? If it's staying close to your set temps then maybe the compressor is having to run that much to keep it cool. How's the insulation and seals?

I should add that we manage right now by manually shutting the fridge off for a few hours here and there. With this our 400 watts of solar and another 400 watt wind gen is able to keep the batteries up, but I couldn't leave the boat for more than a couple of days right now. This is a recent development with our Adler Barbour unit. It may be a thermostat problem, or perhaps the coils are just all gummed up. It is over 22 years old.

On the plus side, the beer is icy cold, so life ain't that bad.


Why go fast, when you can go slow

[chala]

Originally Posted by typhoon

how many Amp Hours is your 12v DC refrigeration using in any given day (24hrs) on average ?

Originally Posted by StuM

We're getting better. It took all of 10 posts this time before someone screwed up the "amps" v "amp hours' thing.

Quote:
"But then solar hot water saves about 5KW a day."

It does happen. It can be taken as 5KW for 24h or 0,2803kWh.
It need just a little mind flexibility.

Originally Posted by sailorchic34

but duty cycle is about 16%.

It is possible to achieve better than 8% in the Tropics on a eutectic freezer-cool box fridge.
32Ah a day, which is in fact 16Ah a day on 24V dc. One hour run every 12 and making 3kg of ice every 24 hours.

[skipmac]

Originally Posted by Mike OReilly

I should add that we manage right now by manually shutting the fridge off for a few hours here and there. With this our 400 watts of solar and another 400 watt wind gen is able to keep the batteries up, but I couldn't leave the boat for more than a couple of days right now. This is a recent development with our Adler Barbour unit. It may be a thermostat problem, or perhaps the coils are just all gummed up. It is over 22 years old.

On the plus side, the beer is icy cold, so life ain't that bad.


Why go fast, when you can go slow

If I recall correctly some previous posts from Richard Kollmann, the controllers on the older machines tend to go bad.

The thermostat should be very easy to test with a Volt/ohm meter to confirm or eliminate that as the problem.

The control module I think Richard Kollmann offers a very inexpensive testing/repair/exchange service for these. Maybe send him a PM.

[zboss]

Originally Posted by skipgundlach

I haven't done an ice melt - because I can't figure out the cat (Shroedinger's) and Heisenberg - any time I'd attempt to measure it, I'd muck with the temperature and add an unknown amount of BTU.

Its easy.

1) Take a 10 pound bag of ice and put into an empty and warm fridge (remove all food and whatnot and then turn off fridge and let warm up over 24 hours)

2) Put 10 pounds of block ice in a bucket and let it melt for exactly 24 hours. DO NOT OPEN FRIDGE OR TURN IT ON.

3) leave fridge off and remove ice and put in a NEW 10 pound block. Don't use the first day as your standard since the ice was cooling the box. The 2nd day is what you use.

4) Weigh the ice leftover after exactly 24 hours. If you have less than about 5 pound you need more insulation. Obviously more ice is better.

[Mike OReilly]

Originally Posted by skipmac

If I recall correctly some previous posts from Richard Kollmann, the controllers on the older machines tend to go bad.



The thermostat should be very easy to test with a Volt/ohm meter to confirm or eliminate that as the problem.



The control module I think Richard Kollmann offers a very inexpensive testing/repair/exchange service for these. Maybe send him a PM.

Thanks Skip, I'll try and figure it out. After 22 years of service I'm kinda thinking a new unit is in order. When I hear about all you with under 50 amp-hr units, I'm just plain jealous.


Why go fast, when you can go slow

[chala]

Originally Posted by Mike OReilly

It's always running full throttle at about 7 amps.

Originally Posted by Mike OReilly

by manually shutting the fridge off for a few hours here and there.

When manually shutting the fridge off, do you use the thermostat to do so by turning it toward warmer?
If not try it, doing it slowly until the unit stop.
It is possible that the thermostat is set to low, to a low level that the unit can not anymore achieve.

[Mike OReilly]

Thanks Chala, I have tried turning it way down, but it won't shut off. I can turn it off using the thermostat. It is possible our old Aldur Barbour just can't keep up now that we're in warmer climes.


Why go fast, when you can go slow

[barnakiel]

I have 4 units (2 freezers, 1 fridge, 1 fridge/cooler) on the boat I work for.

We are burning anything from 120A (empty) to as little as 45A (loaded). There is some variation depending on where we are but not all that big to count for much.

b.

[chala]

Originally Posted by Mike OReilly

After 22 years of service

Their is chances that a 22 years old thermostat be a simple mechanical one, not to expensive and easy to replace. That would be a good start at finding out how good is still your's unit.

[puffcard]

I have a Tartan 37 with a stock 7 cu ft, top load ice box. The only added insulation is 2in of minicell foam to the reefer lids. We use Adler Barbour Super Cold Machine and use the inside of the evaporated as a freezer. In the Bahamas during the winter with a lot of use, we're using 35-40 amp/hrs per day.