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Fridge/Freezer choices

Nigel Bowden

By Nigel Bowden
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Nigel Bowden Gongoozler

Nigel Bowden

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Hello All

 

We've been running a Haier 240v fridge/freezer (goes under counter & from Midland Chandlers) for the past 18 months. It's OK but hammers the batteries so we are switching to 12v and the choices are a Coolzone jobby (again from Midland Chandlers) or an Indel B Cruise Big Fridge (Isotherm) from Marathon. Has anyone had any dealings with either of these products?

 

Ta muchly,

 

Niggle

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steelaway Influencer

steelaway

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Hello All

 

We've been running a Haier 240v fridge/freezer (goes under counter & from Midland Chandlers) for the past 18 months. It's OK but hammers the batteries so we are switching to 12v and the choices are a Coolzone jobby (again from Midland Chandlers) or an Indel B Cruise Big Fridge (Isotherm) from Marathon. Has anyone had any dealings with either of these products?

 

Ta muchly,0000

 

Hi There

 

IMHO switching to a 12v fridge is not going to make much difference if any.

Check out the watts on grade 'A' fridges they can be as low as 500w.

At 240v + 10% loss through the inverter = 2.3 amps

Then ask for the loading in watts on the 12v (say 500w) and multiply it by 20 - divided by 240 = 2.3 amps

This will give you an approximation of the comparative amps and the true loading.

 

I await the thoughts of ChrisW

 

Alex

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chris w Veteran II

chris w

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I don't have any experience of a fridge/freezer on a boat but a modern 12v fridge will draw about 4A, when the thermostat kicks in, at about 50% duty cycle (ie: 50% ON and 50% OFF during the day). This therefore results in an average daily current of about 2A which equates to approx 50AH consumption per 24 hrs.

 

Chris

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steelaway Influencer

steelaway

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I don't have any experience of a fridge/freezer on a boat but a modern 12v fridge will draw about 4A, when the thermostat kicks in, at about 50% duty cycle (ie: 50% ON and 50% OFF during the day). This therefore results in an average daily current of about 2A which equates to approx 50AH consumption per 24 hrs.

 

Chris

 

Hi Chris

 

What watts (?) would you calculate that to be, surely not 48w. Im struggling to understand the relationship between 12v & 240v fridge loads

 

Alex

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chris w Veteran II

chris w

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Hi Chris

 

What watts (?) would you calculate that to be, surely not 48w. Im struggling to understand the relationship between 12v & 240v fridge loads

 

Alex

 

Yes around 50W is correct. A 240v version will be around the same plus say 10% loss in the inverter.

 

Chris

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Nickhlx Veteran

Nickhlx

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Yes around 50W is correct. A 240v version will be around the same plus say 10% loss in the inverter.

 

Chris

 

From the Bosch website... it seems that a standard sized domestic 230 volt a.c. mains fridge ( under the counter) like this one

KTR18P20GB

Logixx Larder Fridge

Net capacity 154 litres, Electricity consumption 117 kWh per year,

 

will use about 2.25 kWh per week.

 

Say, pessimistically, a cheaper one uses 3.5 kWh a week, that is only about 1/2 kWh per 24 hrs, around 42 watts continuous, 3.5 amps continuous, or 42aH per day... and this is being pessimistic with a big ( for a boat) 150 odd litre fridge. I would guess it would be not too difficult to allow 35 aH per 24 hour period for a smaller boat fridge.

 

( do people add extra insulation around their fridges when building in ? I reckon this would further reduce losses if say a 1" thick slab of polystyrene were added to the top, sides and back where you can get to it...)

 

Nick

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ITAfloat Engager

ITAfloat

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I don't have any experience of a fridge/freezer on a boat but a modern 12v fridge will draw about 4A, when the thermostat kicks in, at about 50% duty cycle (ie: 50% ON and 50% OFF during the day). This therefore results in an average daily current of about 2A which equates to approx 50AH consumption per 24 hrs.Chris
I do and my Shoreline fridge used to draw 2.7A when running (not a bad initial guess CW). Shoreline Freezer 3.8A both at 12 volts. Our Inlander Frige was bloodthirsty at 6.7A but considerably older than the shorelines.We used to run a 240v Freezer from the inverter, but put it on a timer - on at 7am - off at 8pm. Never had a problem keeping food frozen as the door was not opened during those times and reduced the load on the batteries. Buying 240v appliances means you have access to some very good A rated equipment. Personally I prefer 12v appliances - keeps things simple and I'm not reliant on the Inverter except for entertainment.
( do people add extra insulation around their fridges when building in ? I reckon this would further reduce losses if say a 1" thick slab of polystyrene were added to the top, sides and back where you can get to it...)Nick
Nick, remember that airflow is all important - that extracted heat has to be released from behind and around the unit. A cheap PC fan on a small solar panel (like Maplin and other stores sell) can help move the air from behind the fridge/freezer, improving efficiency and saving duty cycle time (batteries).Jas
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chris w Veteran II

chris w

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From the Bosch website... it seems that a standard sized domestic 230 volt a.c. mains fridge ( under the counter) like this one

KTR18P20GB

Logixx Larder Fridge

Net capacity 154 litres, Electricity consumption 117 kWh per year,

 

will use about 2.25 kWh per week.

 

Say, pessimistically, a cheaper one uses 3.5 kWh a week, that is only about 1/2 kWh per 24 hrs, around 42 watts continuous, 3.5 amps continuous, or 42aH per day... and this is being pessimistic with a big ( for a boat) 150 odd litre fridge. I would guess it would be not too difficult to allow 35 aH per 24 hour period for a smaller boat fridge.

 

( do people add extra insulation around their fridges when building in ? I reckon this would further reduce losses if say a 1" thick slab of polystyrene were added to the top, sides and back where you can get to it...)

 

Nick

 

The figures quoted in manufacturer's data for fridge power consumption are very optimistic. They don't really mimic real world use but assume the fridge is very well stocked (ie: minimum free air inside) and that the door isn't opened and closed as it is in actual use.

 

Chris

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chris w Veteran II

chris w

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I've been thinking about a 3-way also, as my 12v fridge hammers the batteries. Do they use a lot of gas, any idea how quickly, etc?

 

Meg

 

Can you clarify "hammers".?

 

If you have a typical 3x110AH batteries set-up the actual (Peukert) capacity is 765AH. You can use half of this without damaging the batteries, so say 400AH is available. A 12v fridge will draw 4A and will be ON about 50% of the time. So over a day the total capacity used will be around 70AH (Peukert corrected). Thus the fridge will only sap about 20% of your batteries' available capacity.

 

If the fridge is "hammering" the batteries, then either its an old (higher current) fridge or your batteries are cream-crackered and need to be replaced.

 

Chris

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jeb Collaborator

jeb

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Looks perfect to me and 600 wide

Might get one myself

 

Alex

 

The freezer box is rated a 4* so keeps things frozen as a normal freezer ( I think )

 

Out of curosity what does 127.0 kWh/y work out to in everyday running terms ?

 

Edited to say you might want to consider this one as well.

 

http://www.greenwarehouse.co.uk/index.php?...tail&id=360

Edited by jeb
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Neil@CanalVoyagers Collaborator

Neil@CanalVoyagers

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Do they use a lot of gas, any idea how quickly, etc?

 

I have to say Meg I've got no idea. We have a two-way (240V in winter/hookup, gas in summer) dometic RGE400 fridge/freezer which is excellent but we also have another gas fridge, and the cooker is on most of the day preparing the next meal, so its difficult to tell how efficient it is.

 

The link gives readings of approx. 3.9kWh/24hrs for electric and approx 500g/24hrs for gas.

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chris w Veteran II

chris w

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The freezer box is rated a 4* so keeps things frozen as a normal freezer ( I think )

 

Out of curosity what does 127.0 kWh/y work out to in everyday running terms ?

 

Edited to say you might want to consider this one as well.

 

http://www.greenwarehouse.co.uk/index.php?...tail&id=360

 

It equates to around 30AH per day. A more typical practical figure from others on here, including me, is around 50AH per day for a modern 12v fridge.

 

Remember that manufacturers' figures use unrealistic conditions like the fridge's being stocked full to restrict air movement and the door's never being opened.

 

Chris

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jeb Collaborator

jeb

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It equates to around 30AH per day. A more typical practical figure from others on here, including me, is around 50AH per day for a modern 12v fridge.

 

Remember that manufacturers' figures use unrealistic conditions like the fridge's being stocked full to restrict air movement and the door's never being opened.

 

Chris

 

Thanks Chris

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steelaway Influencer

steelaway

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Our 13g gas bottles last 3weeks to a month. Gas fridge and gas cooker used every day.

Sue

 

Hi Sue

 

We swopped our gas fridge for a 240v one.

We could not believe how long our gas bottles last now - probably 6 months.

Plus we have less condensation and a freezer that does.

We are glad we changed.

 

Alex

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chris w Veteran II

chris w

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If you have a shore mains connection, then a 12v fridge will be running from the charger, if it is a multistage variety, and not from the batteries. The charger acts as a 12v powerpack and doesn't even need the batteries connected to function in this mode. It will run the whole domestic side of the boat all the time you're connected to shore.

 

Chris

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steelaway Influencer

steelaway

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Liveaboard?

 

Personally I'd rather not use my batteries to power my fridge - one's charging regime has to be quite disciplined and I've met too many people who've knackered their batteries.

 

Hi There

 

Live aboard for 1 year - now only 8 months a year.

If I was not moving I would run my engine for around 2 hours every day to heat the water and charge the battery's.

I think even Chris w would agree, that with a good charge controller and good battery's it should not be a problem, it isn't for me.

Replacing gas bottles has almost become a thing of the past.

 

Alex

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