Fridge off overnight

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roaringgirl

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I saw on another thread that switching the fridge off overnight is a way to save energy. I can't understand how this would help as in the morning it's just going to have to use the same amount of energy you 'saved' to bring the temp back down.

I am willing to learn - what have I missed?
 
roaringgirl said:
I saw on another thread that switching the fridge off overnight is a way to save energy. I can't understand how this would help as in the morning it's just going to have to use the same amount of energy you 'saved' to bring the temp back down.

I am willing to learn - what have I missed?
Click to expand...
The only way turning the fridge off at night makes any sense is if you have lots of solar charging capabilities but small battery capacity.
If you super cool the contents of the fridge during the day whilst you have ample power you can then turn off the fridge at night and allow the temperature of the contents to slowly rise over night. This can be set up easily with a Victron smart solar reg to do it automatically
 
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roaringgirl said:
I saw on another thread that switching the fridge off overnight is a way to save energy. I can't understand how this would help as in the morning it's just going to have to use the same amount of energy you 'saved' to bring the temp back down.

I am willing to learn - what have I missed?
Click to expand...
Your correct no real world benefit but many will argue this, energy is energy. You can help by over cooling during the day when solar is available and then switch off over night, this is normal load shedding that large cold stores have done for years, only save money if you can play with tariffs or high demand deals with national grid
 
The energy used depends on the difference between the fridge and ambient temperatures. If, by switching off at night, the average temperature difference is less, then indeed energy will be saved. This may well be a pointless exercise however, because the spoilage of food may well depend on what maximum temperature is reached and for how long. You would keep your food safer and with less energy by just turning down the refrigeration level. If all you keep is beer, then it might well be different, though a strategy such as #5 might also work.
 
Fridges consume a lot of power. Some shore power systems will not supply enough amps to keep up with a fridge. The alternator on the engine will normally cope and charge the battery at the same time
Also fridges are noisy so better off for a quiet night.
When I did an Atlantic passage we had to keep starting the generator to charge batteries drained by fridges and a freezer.
Best solution found by my mate who was a long term livabourd was to do without a fridge.
 
Are yacht fridges that much more noisy than domestic fridges? I don't think they can be that loud, but then again I don't have to sleep next to one.

Fridges are intended to switch themselves on and off according to temperature, so assuming the thermostat is set correctly, turning the fridge right off will only save energy at the risk of food spoilage, as noted above.

If you're asleep overnight, then the fridge will not be opened, so it will maintain the lower temperature better, anyway.
 
They’re such a fantastic resource to have, chilled milk, retaining fresh food for longer, etc, but in addition to being power hungry they’re noisy. Well ours is. Through the day you sort of zone out to it switching on humming away and then switching off, but at night all is peaceful and then suddenly….donk… it switches on and hums away for a bit and it’s loud when all about is so quiet!
So I switch it off last thing and keep the fridge doors firmly shut thereafter. Keeps the coolness reasonably and on rising next morning, switch it back on. By the time I’ve finished making the tea, it switches off and goes into its daily cycle, having re established its cool float temp. But it is so noisy.
Let me know, anyone, of an efficient fridge that’s quiet and not power hungry and I’ll go for it. Possibly.
 
shortjohnsilver said:
They’re such a fantastic resource to have, chilled milk, retaining fresh food for longer, etc, but in addition to being power hungry they’re noisy. Well ours is. Through the day you sort of zone out to it switching on humming away and then switching off, but at night all is peaceful and then suddenly….donk… it switches on and hums away for a bit and it’s loud when all about is so quiet!
So I switch it off last thing and keep the fridge doors firmly shut thereafter. Keeps the coolness reasonably and on rising next morning, switch it back on. By the time I’ve finished making the tea, it switches off and goes into its daily cycle, having re established its cool float temp. But it is so noisy.
Let me know, anyone, of an efficient fridge that’s quiet and not power hungry and I’ll go for it. Possibly.
Click to expand...
We have no complaints about ours,and our boat is small, light and the whole thing reverberates with the engine. It’s silent in the day, unnoticeable I should say. At night it doesnt wake us, but you can just hear it run if you’re awake anyway. Not intrusive. It’s a portable one from vevor. Power wise, we’re a trimaran with small batteries, an outboard and some solar, it hasnt caused any issues yet.
 
I don't hear ours but my wife sometimes mentions it. We generally have it on continuously, turning to low power if we are sailing, anchored or moored, which is adequate. A fridge makes an enormous difference to cruising comfort. As well as such delights as cold milk, we can eat fresh meat or other food in the evening without having to race to get into harbour before closing time, with the penalty for failure being a FB meat pie.
 
geem said:
Why do you need lithium for that? We have fridge and fridge freezer on constantly with plain old lead batteries and solar
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I have to agree with Geem. The fridge and freezer have no idea how the electricity is generated nor stored. We too use 'old fashioned' lead batteries, solar, wind and a hyrdogen (trailing impeller) - we make 'power' which the fridge consumes. If you want to use less power - them make your fridge more efficient (by using it efficiently (only open to remove the day's food, don't continuously open and close) and (beef up the insulation and vent to the compressor + remove warm air from round the compressor. Your fridge is not entirely stupid - it may not know (or care) how the power is produced and stored but it will thank you for being efficient, adding insulation and producing a better airflow by cycling on and off less frequently.

A different option to turning the fridge off

When your batteries are at float - turn the thermostat to a colder setting this will use the excess energy you are 'making'. Even better make ice, cold air is a waste of time - ice is a more efficient use of space than air. When you no longer make excess energy, say at night when your solar offers no contribution, then turn the thermostat to a warmer, or less cold, setting. We carry this to an extreme and will recharge, say iPad and laptop, bake bread using an electric bread maker, use the desalinator etc when the batteries are at float (and/or) when we are running one or both engines and the batteries might not be at float but are accepting less input. When your batteries are near float your alternator can still produce to its maximum rating - use it (to recharge the iPad, or bake bread, or run the desalinator - or further cool the fridge and freezer).

Like reducing weight and reducing weight in the ends - treat it with religious fervour and it will become second nature. It is easy to become inefficient - but is equally easy to become efficient.

Jonathan
 
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Our fridge is 220v ac and our inverter ( which is mainly for the fridge plus small devices) uses 1AH even when not working. We may consider having the inverter on for 30mins every 2 hours ( or similar) if our solar is low.
The fridge is near our berth but there is very little noise.
 
I would reiterate the advice to wind the stat down during the day when power is plentiful, then simply wind the stat up overnight, this will reduce the compressor cutting in.

Noise and vibration depends a lot on the type of compressor, so the miniature Danfoss piston compressors are quiet as a mouse, but the Matsushita Swing compressor which more akin to a large solenoid valve makes quite a level of vibration which in turn rattles the fridge and anything inside or nearby, indeed it is the stuff around that generates the noise.

Keeping the fridge full especially, with cans or food or liquid (beer or cider of course) will improve the amount of cold it contains, and will reduce its cycling.

Obviously if the fridge is low on charge and hence struggles to get the temperature down the compressor will run for longer, and if the condenser is not well vented the compressor has to work harder and draw more power. A simple computer cooling fan uses only a few watts and will easily circulate the dark and mostly forgotten space behind many fridges.
 
caravan fridges are virtually silent as they don't have compressors. They are also 240v or 12v or can also run on gas (but I've never understood how that works.
Turning off fridge overnight does work in UK usually as overnight temps low but in the med (or Caribbean) overnight temps are too warm (mind you as the original post was about small boats, you're not likely to find yourself in either position with that sort of vessel.)
 
shortjohnsilver said:
Let me know, anyone, of an efficient fridge that’s quiet and not power hungry and I’ll go for it.
Click to expand...
We happily run ours 24/7. It is water cooled with a hull mounted sintered bronze cooling plate outside the hull. Compressor is separate from the cabinet allowing extra insulation all around the cabinet. About half the power consumption of the same volume air cooled unit it replaced. Standard Danfoss compressor but not noisy enough to disturb sleep.
 
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