120vac Refrigeration Questions

[lorenzo b]

If you average $1.50 a day buying ice it will be many years before you break even on a freezer and refrigerator, and then of course they'll break down and drive you nuts. You may want to look into a hand built system with a used compressor, but I would think it would be hard to make it efficient. You will need electricity for lots of other stuff on a boat, so what all the books on the subject advise is to make a spreadsheet of all your projected needs and than figure the best way to generate that much electricity and than some. Obviously you'll need power for your computer, navigation, and lights etc.
If you're living in a truck camper you've already figured out that less is more, and usually a lot more.

[motion30]

The bottom line for me is... A 110v unit works well (keeps thing cold) and is cheap but Uses to much power when not tied to the dock. I am replacing my unit with a 12v marine Refrigerator

[lorenzo b]

So help me out here. Given the relative simplicity of refrigeration and the rock hard laws of physics, why would a 12v system be so much more efficient at freezing one kilo of water than a 120v system? It always seemed to me 12v refrigerators were more efficient because they were better insulated and much smaller. How much does a 12v 3.2 cu ft refrigerator use? If you amortize the cost difference over say 5 yrs, figure in the cost of larger batteries etc is there really much of a difference? I'm asking, I don't know.

[motion30]

I don;t know it is so much a cost differance, more a issue in using up the battieries while at anchor, with the 110v unit off the inverter I need to charge twice a day I am hoping to cut that to once a day, as I said the 110 unit is using 9 amps the 12 volt unit uses less the 3amps

[lorenzo b]

If what you're saying is that your 110v unit uses 9 amp @ 12v off an inverter and a comparable 12v unit uses 3 amps, that's a hugh difference. It just doesn't make sense to me.

[motion30]

I don't pretend to be a electronics expert I just know what my 3.5 cf frig uses according to the inverter remote readout.The amp rating for the 12 volt unit is fron the spec sheet And yes is it is a huge difference

[cantxsailor]

Engel, Engel, Engel or Engel. For the best working, most trouble free, energy sipping, next to bullet proof piece of equipment I suggest, you guessed it, ENGEL.

They can be plugged into both 12v and 110v at the same time. If the 110v fails it will automatically switch to 12v saving all your beer from the heat.

Mine(mod35) has been running for 2 years nonstop. I use it in the boat and then in the camper when travelling or, like this weekend, at my kids new but unfinished house for a birthday party involving icecream(and of course, beer). An oil field worker friend of mine turned me on to Engel a few years back. His is about the same model as mine but looks like its been dragged behind the truck. It has been dropped, kicked and generally knocked around in the back of his truck for a bunch of years and other than having to replace the lid(it got lost somehow) it still works flawlessly.
Its toughness is what sold me.

It keeps my beer cold and will freeze whatever I want hard as a brick. They come in several sizes, mostly to big for my boat. You may consider them small but remember you won't have all that ice in there taking up space for, you guessed it, more beer.

Mine is about the same size as the usual upright kind of fridge you can get from West and such, but is top loading. This helps keep the cold in the box if nothing else.

They draw about half of what the AddledBugger types do and are about the same price and dont break at the first bump because they have only one moving part.

There are a couple of other manufacturers but I have no experience with them.

As you may guess I love my Engel. It rates right up there next to the tiller pilot for most useful things on my boat. Just behind the sails and ahead of the Dickinson propane stove.

I have no financial interest in any of the brands mentioned other than having bought them but they work well and that makes me happy..........m

[Northeaster]

Does an Engel (or similar unit) require any airflow? Or could it be placed inside a large icebox? It would not be tight on the sides, but would not get any moving air either.

[lorenzo b]

Nice looking unit, the very largest is 2.89 cu ft, uses 0.7 to 3.6 amps, and costs $1149 plus $200 in shipping, Will plug into 12v or 110v

Sams club refrigerator with freezer compartment is 3.2 cu ft, uses 1.2 amps, and costs $139, and plugs into 110v

$1200 buys a lot of beer

[nine lufts]

Originally Posted by lorenzo b

....
$1200 buys a lot of beer

Man speaks great truth...

[Boracay]

The big difference between a 12V and a 120V (230V for me) is that the 12V unit could have 4" (or more) of insulation, and be quite small, wheres the 120V unit has only (about) 1" of insulation and is (relatively) big.

On a (very) rough calculation 4" of insulation will require 25% of the power of 1", and 40 litres will need 50% of the power of an 80 litre unit.

So a well built 12V unit may need 12.5% of the power of the larger 120V unit (including inverter conversion and door losses this could be as low as 5%).

[nine lufts]

While the old Maytag may have greedily drawn juice like what's-her-name back during prom night, and the what-if could create positive energy and cause the Kalahari to ice-over, I think we've been dealing with a mixed bushel of fruit, so far.

Most discussions and research have been centered on 'mariie', and the 12v systems marketed for that application. Could there be some new 12v appliances that would actually work...

Until real-life tests are typed, and something closer to tangerines and oranges are compared, we'll all be left with just memories of prom night...or something like that...

[mesquaukee]

If you plan on hanging on a hook for extended periods of time forget the 110 volt fridges and freezers. Bite the bullet and go with a system meant to be in a boat.
If not you will be going through batteries like crazy.
I hear 1.2 to 1.4 amps at 110 volts or 13 to 15 amps at 12 volts, running 40% to 60% of the time (if it is a capacitor run motor it will be higher). That’s 150 to 220 amphrs a day. That is horrendous, you will spend 4-6 hours a day charging batteries that will not last very long with that sort of abusive charging regime.
A well insulated box and a proper marine system you will be using 25 to 60 amphrs a day for a fridge and a freezer. Solar panels would easily power it. You would save a ton of money on batteries, fuel, engine maintenance, wear and tear and just pure aggravation of having to spend the time being there charging the batteries when you want to be snorkelling.

[endurance]

"In the case I mentioned above, the RLA was only about 9 amps @ 120V AC, but the LRA rating was 60 amps @ 120V. Now, how're you going to pull 60 amps thru an inverter/charger with a transfer switch rated at 30A?

Bill[/quote]"

I don't have any experience in inverters and AC systems on boats, but having engineering background and have had extensive experiences in specialty refrigeration design .... to add my two cents to Bills comments ...

A 120 VAC compressor draws a significant amperage at starting and slowly drops down to a running amperage - the magnitude of 'Amp surge' and the duration would depends on many factors but mostly depending on the design and pressures (ex, capillary system will take longer to reach run Amps than thermostatic expansion system (TXV)- most of the AC are of capillary system on older system w/low SEER. Newer systems with higher SEER most likely have a TXV.

To minimize the motor start-up Amp surge and to increase the system (electrical) efficiencies, most of the AC systems should (if not install) have start and run capacitors.

Rick

[motion30]

Originally Posted by endurance

"In the case I mentioned above, the RLA was only about 9 amps @ 120V AC, but the LRA rating was 60 amps @ 120V. Now, how're you going to pull 60 amps thru an inverter/charger with a transfer switch rated at 30A?

Bill

"

I don't have any experience in inverters and AC systems on boats, but having engineering background and have had extensive experiences in specialty refrigeration design .... to add my two cents to Bills comments ...

A 120 VAC compressor draws a significant amperage at starting and slowly drops down to a running amperage - the magnitude of 'Amp surge' and the duration would depends on many factors but mostly depending on the design and pressures (ex, capillary system will take longer to reach run Amps than thermostatic expansion system (TXV)- most of the AC are of capillary system on older system w/low SEER. Newer systems with higher SEER most likely have a TXV.

To minimize the motor start-up Amp surge and to increase the system (electrical) efficiencies, most of the AC systems should (if not install) have start and run capacitors.

Rick[/quote]
It that what is called a hard start?