220V Fridge in a Sailing Boat?

[ErikFinn]

Merry Christmas!

I live aboard in my recently acquired Beneteau Oceanis 430 and wanted to ask the forum members on their opinion on what they think of this idea about installing a 220V 150-170 liter fridge aboard.

Why I'm tempted:
-Cheap (200-300 USD).
-I have free shorepower at the marina where I keep the boat. (Yes, free).
-I live aboard and don't plan to do long trips for a few years, but 1-2 sailing trips in Malaysia/Thailand area (tropics), so I don't see the benefits of a new marine fridge necessarily obvious (am I wrong?)
-It would seem nice to have a large "house-size" fridge aboard.. (buy a boat and try to make it a house..? LOL ).

Cons:
-Not marine quality, issues?
-Would require some carpentry in the galley in order to be able to install.
-The space would be pretty confined (in a "closet"); would I have problems with the heat/overheating; would I need an additional external fan to circulate the air around the machinery)

The specs of a typical fridge this size are 220V, 0.57A, 85W (see Pic); if I was to run it from the 12V batteries through an inverter:
-would a 300W inverter be the best size? (I have a 1500W inverter but this would not be ideal?)
-am I correct to say that the setup would draw about 7 Amps per Hour? (85W/12V=7.08A)??

Furthermore, If I was to run the fridge as above continuously, I would use somewhat less than 168Amps per any 24 hour period? (less because the compressor is not running ALL the time, maybe about 50-75% of the time..?)

I have 8 X 85W solar panels (Solavolt SV8500, rated 85W each).
The house batteries are 4 X Trojan T-105Plus 6V Deep Cycle, 12V system (and a fifth larger for engine start), should I have more batteries for a "better" system?

What do you experts think? Does this sound like a stupid idea or could I do it (and keep the batteries full without running the engine) while sailing? I also have a Air Marine 400W wind generator, but for this discussion I'd disregard it and just concentrate on the Solar panel capacity & the batteries.
The boat is still new to me and not sure if my calculations above are correct, do they sound about right? Or not..?

-Erik

[MarkJ]

Im not an expert but i would love a propper fridge.

[Captain Bill]

You need to account for your losses in the inverter and you need to make sure you get a true sine wave inverter. I had a 110V ice maker refrigerator on a modified sine wave inverter/shore power/genset. The thing worked great on shore power or the genset, but on the inverter it would not get cold enough to make ice. The compressor motor would run on the modified sine wave but not very efficiently. I would guess you have ample generating capacity especially if you count the wind genny as contributing something and you have the ability to top up with the engine on cloudy days. You might want a little more storage capacity if multiple cloudy days are common in your area.

[twistedtree]

What are your running currently? You hinted to a smaller marine fridge? I ask because you will of course be eliminating that load, so what really matters is how much more load the new fridge would present vs your current unit.

You could try a 300W inverter, but might find it doesn't work with the startup load of the fridge. Inverters can handle a short surge, and the fridge draws a short surge. Which one is bigger is anyone's guess. But if you run off the 1500W inverter, I don't think it's the end of the world. And that will only matter when away from the dock and shore power, right?

As for cabinet work to fit the bigger fridge, I'd suggest adjusting your cabinets to handle a "standard" fridge size, if there is such a thing in the range you are considering. That will make future swap out easier, and if your fridge breaks on you, just go buy another one for $300. But this may be easier said than done.

Ventilation is important. Without it the fridge will have a longer duty cycle (compressor running higher % of the time) and use more power. If you can't get good natural air flow then a small fan is probably a good investment. I'd pay a lot of attention to this when reworking your cabinets. The best natural venting will be if you can create a chimney effect with an air inlet below the fridge, and an outlet above. The heating from the fridge will cause natural circulation of air in the bottom and out the top.

[mcarling]

Your useable battery capacity is about 3KWh. To go with your solar panels and wind genny, I would want 10-12KWh useable capacity. I would buy 4x 700Ah or 1000Ah lithium phosphate batteries, which would weigh about the same as your current house bank. With your current battery capacity, you'll be running your generator and burning diesel more than necessary -- unless you're not making use of your solar and wind capacity.

The only way to find out whether or not you'll have heat circulation problems behind your fridge would be to try it.

It's better to have an inverter that's too large than too small, so I don't see a reason to replace your inverter with a smaller one.

I would expect your compressor to run a lot less than 50% of the time -- except perhaps in extremely hot weather.

Personally, I would get a DC marine fridge (I have no use for a freezer) but I understand that price is a consideration.

[Pete7]

Whilst the fridge is a cube a yacht hull isn't. Hidden behind the cabinets is the curved side of the hull so fitting a full size fridge might be tricky. However, if your marina based for a couple of years a cheap household fridge and chuck it out when you depart would make sense.

I would turn it off when at sea as they don't like being tipped,also you need to secure the door or the contents will be all over the cabin after the first tack.


Pete

[ErikFinn]

Thank you for all the replies,
At the moment the original built-in fridge is inoperative. At a minimum it has a leak (I was told by someone who knows the boat) and being original its now almost a quarter century old. I suppose the sensible thing would be to investigate if it could be fixed or if not then replace. But I will have a lot of other expenses so I wanted to think about this more econimical(?) option.. And in a way it would be nice to open the door of a "propper" fridge than crawl over the original one and try to find whats in there..
I don't have a generator and don't plan to get one, there just isn't enough space imho. ideally I would like to run the fridge from the solar panels & batteries when out of marina but not sure how practical this would be.

[mcarling]

With your solar capacity plus wind capacity and batteries upgraded to 1000Ah, you might be able to keep that fridge running at a relatively warm setting without a generator. Maybe. Set the fridge to a relatively cold setting or go to a very hot climate and I guess you can forgot it.

[swisscraft]

If I would have the space and the energy: Thats what I would do if I ever have a new boat!

A 12V Fridge has only one advantage: Power saving. And that is relative. A 12V unit can use from 50 - 100A depending on size, isolation, two or one compressor and so one. Forget the quality issue! I really do not believe there is much diffference in terms of compressor and thermostat. Usually a boat fridge has better isolation (wish full thinking). You can buy 5 - 10 household fridges for the price of one "boat unit" if you take proper isolation in consideration. And you can buy them everywhere if it will ever fail.

And your wife will love a normal fridge much more than this crawl in compartements....

[noelex 77]

You have a lot of solar and wind and combined with shore power you can get away with a reasonably inefficient fridge.

There are some new very efficient domestic fridges with vacuume panels that rival, or even better traditional marine options for efficiency. These would be worth looking at. I suspect you could get something with a much lower consumption for not much more money.Look at the energy star ratings.

It's very difficult to predict the consumption from the power input. The duty cycle is very dependent on the insulation. The listed power draw also tends to maximum ( although for a few seconds at start up it can be higher).
220x0.57=124w, not 85w, but you should see consumption considerably less than 168AHrs it will depend on temperature, but it should be less than 100AHrs.

Install a 12v fan to exhaust the hot air behind the fridge.