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12 volt V 240v fridge .....opinions


Chris-B
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Planning the fit on Tipton and got to thinking of fridges ... 

I have always previously gone down the shoreline 12 v route and been happy ..but technology and kit changes along with our needs 

Tip will be built for boating and is not intended to be a long term Liveaboard so I was thinking that a off the shelf household fridge running off the victron inverter whilst not as power frugal as a shoreline is a dammed sight cheaper 

please convince me why or why not to go down this road ...I am open to all suggestions 

thanks

Edited by Chris-B
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It makes a lot of sense to go for a mains fridge - cheaper, more efficient. The overall power consumption will probably be pretty similar after taking into account inverter losses. The only counter-argument is that the reliability of refrigeration on board will become the product of the fridge reliability x inverter reliability, ie lower. So it depends on how much of a disaster losing the fridge due to loss of mains power would be.

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2 minutes ago, LadyG said:

You have to buy an inverter

Got one already 

11 minutes ago, nicknorman said:

It makes a lot of sense to go for a mains fridge - cheaper, more efficient. The overall power consumption will probably be pretty similar after taking into account inverter losses. The only counter-argument is that the reliability of refrigeration on board will become the product of the fridge reliability x inverter reliability, ie lower. So it depends on how much of a disaster losing the fridge due to loss of mains power would be.

Victron imo is reliable enough , however I do have a spare sterling inverter that I can bung in a box onboard just in case .. your comments Nick echo what I feel 

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Modern fridge casings are the same for both 12v and 240v.  They are the same size as older ones.  The insides are not!  That is the price of efficiency.  Condensers are usually on the sides now, so  the effective width of the fridge has gone up by 100 mm to allow enough vent space either side.  Plan your kitchen accordingly.  Include a bilge fan for a 12v fridge, to improve efficiency.

All fridges eat power, so a solar panel to collect enough for the chosen fridge  is a good idea that allows you to stop in one place for a couple of days without starting up an engine.

 

N

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15 minutes ago, BEngo said:

Modern fridge casings are the same for both 12v and 240v.  They are the same size as older ones.  The insides are not!  That is the price of efficiency.  Condensers are usually on the sides now, so  the effective width of the fridge has gone up by 100 mm to allow enough vent space either side.  Plan your kitchen accordingly.  Include a bilge fan for a 12v fridge, to improve efficiency.

All fridges eat power, so a solar panel to collect enough for the chosen fridge  is a good idea that allows you to stop in one place for a couple of days without starting up an engine.

 

N

It does seem to be the case that the firms converting fridges to 12v tend to pick a very cheap and basic mains fridge to convert, with concomitant poor insulation.

 

Yes a lot of fridges have the radiators built into the side and a plastic (flammable) fridge back, but after the Grenfell disaster these got a bad name. One can still get fridges with radiators at the back and I suspect they may increase in number.

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When my 12v fridge broke down I replaced it (temporarily, I thought at the time) with a 230v. There was no noticeable difference in energy consumption so I ended up keeping the 230v. The only down side is that you are reliant on the inverter but you have a good brand in Victron.

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I have 'back-up' in that I have a 230v Freezer and 12v fridge, should the inverter fail then at least I still have the small freezer box in the fridge and chilled meats, veg etc, should the fridge fail then I can defrost the stuff in the freezer.

 

We are quite 230v dependent as in addition to the freezer we have : electric kettle (gas hob kettle for back-up), microwave (gas hob & oven as back-up) Air-fryer (oven as back-up) and Twin-Tub (bucket and a big stick for back-up)

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Sorry to hijack again, but as many know, I am on electrician number seven. We [number 7 and I] agreed to do as little electrics as possible, as the can of worms is functioning.

 

HOWEVER:  there is an aged 12 volt fridge presently run from the bow batteries [probably], it works, but the fridge [built in] needs replaced, there is no room for a bigger fridge.

ALL BOAT batteries are connected to one busbar which has three isolator switches [ cheapos]

Number six electrician ran an undersized DC cable in preparation for a replacement 12 v fridge which never went ahead. What size and type of cable do I really need,  can I double up the undersized cable, to make it carry twice the load of one cable? This double cabling would go back to the stern, but I am not clear how they have to be wired to recieve 12 volt electricity?

 

PS .....I am considering  re routing the fridge cabling to the stern where the main domestics [450ah] are located. and doubling up the undersized cable

If I go 240v  I need to think it through regarding replacing the 20amp battery charger, an obvious answer is an 80 amp charger inverter, we are looking at another thousand £, again.

Edited by LadyG
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It's all been said - more than once..

However if you're doing a bit of proper cruising that people used to do and - especially in today's pandemic environment - I suggest a 'proper' fridge freezer from a mid range manufacturer - such as Liebherr who tout theirs as being a bit more efficient as the rest of the herd?

Yes, they're tall but they're good at making ice (....) and of course you can carry more froze food / freezable food than you can in an undercounter fridge.

 

 

 

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2 minutes ago, LadyG said:

What size and type of cable do I really need,  

That cannot be answered without knowing the length of run (there and back) AND the wattage of the fridge with the compressor running.

 

 

3 minutes ago, LadyG said:

can I double up the undersized cable, to make it carry twice the load of one cable?

Yes, but it is a bodge, you need to get both cables so they are 'properly and fully connected', should one wire break or become disconnected you are back down to a single wire.#

 

DO IT PROPERLY AND DO IT ONCE.

6 minutes ago, LadyG said:

I need to think it through regarding replacing the 20amp battery charger, an obvious answer is an 80 amp charger inverter,

What do you expect to gain going from a 20amp to an 80 amp charger ?

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and if one cable did go open circuit the fuse would then likely be oversize so a further fault could set the cable on fire.

 

For 12V fridges you need to use cable with a minimum conductor cross sectional area of 1 sq mm for each metre of run between battery and fridge. Use the same for the negative.

 

If its to be a mains fridge then as house power circuits tend to use 2.5 sq mm conductors but that's for ring mains, for a spur system it may need larger but I am sure that 2.5 sq mm CCSA would be fine for a  spur for a mains fridge (not the AC experts will tell me I am wrong!)

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2 minutes ago, Tony Brooks said:

If its to be a mains fridge then as house power circuits tend to use 2.5 sq mm conductors but that's for ring mains, for a spur system it may need larger but I am sure that 2.5 sq mm CCSA would be fine for a  spur for a mains fridge (not the AC experts will tell me I am wrong!)

Yes, 2.5mm2 would be fine for any 230V 13A socket outlet. 

20 minutes ago, LadyG said:

can I double up the undersized cable, to make it carry twice the load of one cable?

What would this achieve? The cable still has to be run, which is the most time-consuming (ie expensive) part of the exercise. So run a correctly sized cable while stripping out the existing cable which can be kept for other uses.  

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3 minutes ago, WotEver said:

Yes, 2.5mm2 would be fine for any 230V 13A socket outlet. 

What would this achieve? The cable still has to be run, which is the most time-consuming (ie expensive) part of the exercise. So run a correctly sized cable while stripping out the existing cable which can be kept for other uses.  

or if you are lucky use the undersized cable as a pull string.

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1 hour ago, Alan de Enfield said:

That cannot be answered without knowing the length of run (there and back) AND the wattage of the fridge with the compressor running.

 

 

Yes, but it is a bodge, you need to get both cables so they are 'properly and fully connected', should one wire break or become disconnected you are back down to a single wire.#

 

DO IT PROPERLY AND DO IT ONCE.

What do you expect to gain going from a 20amp to an 80 amp charger ?

The 20 [180 amp boost] amps is ancient auto type,  will not energise a 600 nominal battery bank, cannot be left on, as it will just keep puting 20 amps in to boiling point!

I am not even sure I will need a charger this winter just keep moving every 2-3 days, or buy a genny,

Edited by LadyG
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26 minutes ago, LadyG said:

it will just keep puting 20 amps in to boiling point!

No it won’t. Not unless it keeps raising its voltage up to 20-odd volts.
 

The 600Ah batteries will eventually demand less than 6A. However, if the voltage then remains much above 14V then over a period of time it will cause both positive grid corrosion and eventual drying out of the electrolyte. But it won’t ‘pump out 20A until boiling point’. 

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3 hours ago, BEngo said:

Modern fridge casings are the same for both 12v and 240v.  They are the same size as older ones.  The insides are not!  That is the price of efficiency.  Condensers are usually on the sides now, so  the effective width of the fridge has gone up by 100 mm to allow enough vent space either side.  Plan your kitchen accordingly.  Include a bilge fan for a 12v fridge, to improve efficiency.

All fridges eat power, so a solar panel to collect enough for the chosen fridge  is a good idea that allows you to stop in one place for a couple of days without starting up an engine.

 

N

Going down the mains route now for sure , NO solar panel as a) I dont like clutter on my cabin top and b) I really do not need one 

Decent alternator / battery setup and all will be good for what we need 

However I will put a 12v computer fan in to aid with air flow .. top idea thank you

 

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I would like to see real back to back figures, consumption for a 240v fridge and consumption for that same fridge converted to 12 volts. My guess is that the 12volt fridge would be better but I don't know by how much. A high quality DC compressor must do better than a mass produced 240v job? though the relative fundamental electrical  losses in 12v DC machine and a 240v AC machine will be a factor (think Travelpower).  The 240volt fridge will incur the inverter loss but the 12 volt fridge will have a little volt drop in its (thick) cables. 

 

If you are a 240volt boat with the inverter always on for other stuff then a 240v fridge must be the way to go, but installing an inverter just to drive a 240volt fridge? I am not sure. For many boats the fridge will be the biggest consumer of amp-hours so its worth getting it right

 

..................Dave

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How long have you had Tipton and what are your plans? I remember her as a quite pretty unconverted boat, are you doing an undercloth thing or putting on a full cabin? I believe she was previously purchased by a member of this forum who spent ages trying to get her. Before that she was a coal boat on the K&A, I assume this is the same boat?

 

..................Dave

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