12v Fridges

[Jocave]

Looking to purchase a 12v compressor fridge/cool box , at the moment we are using a simple 12v cool box but its pretty useless and heavy on juice, we have limited space so was thinking of buying a 12v compressor cool box , just wanted a second opinion on them ,the smallest one is around £300 ,its only to keep a couple of pints of milk, a couple of bottles of wine and maybe bacon ,eggs etc , are they worth the outlay or is there a better option ??

[Jocave]

Was thinking something like this .

http://www.force4.co.uk/dometic-cf-16-portable-fridge-freezer.html#.WXJVnKDTXqA

[ChrisB]

I have a waeco fridge that was fitted by Viking. They are very good fridges and have a useful freezer compartment at the top.

Downside draws about 4 amp and in the still of night I can hear it sounding like a distant outboard. What I do is fill the freezer compartment with coolbox ice bricks that freeze during the day, I then turn it off when I go to bed, no noise and no battery drain then turn it on when I put the kettle on.

Waeco/Dometic are good equipment, to work well you need compressor type but you will get some noise and battery drain.

 

[Viking23]

 A few weeks ago I rewired the 12 volt supply to our aging electrolux three way fridge, as the original wiring was getting quite warm, and the voltage drop excessive. The new cable run was shorter and a much thicker cable. 

I was now surprised to see that the current at 12 volts was close to 10 amps. This is an absorption fridge, not a compressor type. It runs fine when on 240 on electric hook up, where a thermostat controls it well, but at 12 volts there is no thermostat,  and the consumption of 10 amps at 12 volts is 24/7 totally unacceptable. The idea was, when cruising, we could switch to 12 volts, but this puts a considerable drain on the battery as the honda outboard only puts out 6 amps at cruising speed.

Next visit I am going to take a digital max min thermometer and log temperature variations, and I am going to experiment with a current limit device to limit the power the fridge takes  to 5-6 amps when cruising and then monitor the temperature. If successful, then I might fit an electronic thermostat.

Note... I would not use a current limit on a compressor fridge, as this could cause considerable damage to it, but an absorption fridge works in a different and totally inefficient way, (30 year old technology where ammonia was king) proportional to the heat input, either from a 240 volt or 12 volt heater, or via a gas flame that can either be low medium or high. A very inefficient system, that we have managed with for nearly 30 years lol.

The fridge has been modified with a flame trap, to meet the BSS so can be used on a petrol driven vessel. So it looks like we will continue to use it on gas when away from the mooring, but it is heavy on propane. 

The 12 volt powered fridge is the biggest killer of leisure and marine batteries, and battery voltage monitoring is essential to give batteries a reasonable life.

If I was starting afresh, then I would certainly consider a compressor fridge that worked on 12 volts dc The one mentioned looks a good option, but we might need a slightly larger one to chill more bottles of wine and cider etc 

At this stage of my boating career, and health  it will be difficult to justify spending £££ on a new fridge, £££ can buy a lot of propane lol but... if it broke down tomorrow, I would rip it out and buy a compressor one on a 24 hour delvery lol... and refurbish the galley, new sink, new cooker, new work top etc etc. 

So seeing the coolbox link, wow it is low consumption, and if our current fridge ever breaks down, then worthy of a look. 

If my electronic control with current limit actually works then I will report back.

As most of you know, I like technical challenges, 

Richard

[grendel]

does anyone know if you can get larger peltier based fridges (like the little ones you get to put a couple of cans of drink into.

- goes and looks -

yes they do - eg http://www.drinkstuff.com/products/product.asp?ID=10237&gclid=CjwKCAjwzMbLBRBzEiwAfFz4geb18gmKNM0gx79Tmc9yZ-K71BD-0HIquA6wCS4G9OuWp7sqQ0ZooxoCV40QAvD_BwE#.WXLf5FX56Uk. rated at 0.18kWh/ 24 hr

but it only cools to 16 degrees below ambient, so they say not suitable for perishables, but my reasoning if you just want to keep something (some milk, bacon, a few cans) cool for a few days and its going to be used - its better than no fridge.

[ChrisB]

Thinking about it more I think comsumption is about 4.6 amp, but I will switch it on and see when I go to the boat later. A few years ago I fitted a NASA battery monitor and find it very useful. Another point about Waeco/Dometic products is if your batteries are showing signs of age and the pd drops to below 11 volts they will turn off.

[ChrisB]

1 minute ago, grendel said:

does anyone know if you can get larger peltier based fridges (like the little ones you get to put a couple of cans of drink into.

- goes and looks -

yes they do - eg http://www.drinkstuff.com/products/product.asp?ID=10237&gclid=CjwKCAjwzMbLBRBzEiwAfFz4geb18gmKNM0gx79Tmc9yZ-K71BD-0HIquA6wCS4G9OuWp7sqQ0ZooxoCV40QAvD_BwE#.WXLf5FX56Uk. rated at 0.18kWh/ 24 hr

but it only cools to 16 degrees below ambient, so they say not suitable for perishables, but my reasoning if you just want to keep something (some milk, bacon, a few cans) cool for a few days and its going to be used - its better than no fridge.

Actually for what you describe they are very good. I have a Dometic SC30 that I bought for the car boot. It is 12v and 240v so can be carried into hotels. It makes a picnic or long journey much more enjoyable. It was also very useful for carrying my late wife's Penicillin based drugs on hospital visits, transfussion days etc as they should be kept refrigerated and it did the job very well.

It is one of these, but they have changed the colour mine is blue.

[Vaughan]

Sod's Third Law of Engineering. If you want energy, you will always have to pay for it, somewhere down the line.

The medium sized Electrolux plain 12v fridges that we used to fit would use around 45 amp/hours per 24 hrs, in other words, the full working capacity of one 110 A/H domestic battery. That's why we preferred gas, in those days. The newer big Waeco type 150 litre domestic ones, with freezer compartment, don't really use much more. All the same, one fridge means you need one extra domestic battery. This might mean you need a bigger alternator, which would take more horsepower off the engine (90 amps equals 4.5 horsepower) so less power for propulsion and higher fuel consumption. See what I mean? You have to pay for it somewhere down the line.

The Electrolux 3-way fridges were not designed for boats, and until recently, there was not a gas one, that was. They use a lot of current on 12 volts, as Viking has discovered, and are normally wired so that they will only come on when the engine is running, as in my camper van. When you stop for the night, you turn on the gas or plug in the shore power.

I would always look at the wattage of the fridge before you choose one. If it is more than about 40 watts, you are going to need battery capacity.

[grendel]

the peltier one I linked above is rated about 48W so 4A at 12v.

[ChrisB]

3 minutes ago, Vaughan said:

Sod's Third Law of Engineering. If you want energy, you will always have to pay for it, somewhere down the line.

The medium sized Electrolux plain 12v fridges that we used to fit would use around 45 amp/hours per 24 hrs, in other words, the full working capacity of one 110 A/H domestic battery. That's why we preferred gas, in those days. The newer big Waeco type 150 litre domestic ones, with freezer compartment, don't really use much more. All the same, one fridge means you need one extra domestic battery. This might mean you need a bigger alternator, which would take more horsepower off the engine (90 amps equals 4.5 horsepower) so less power for propulsion and higher fuel consumption. See what I mean? You have to pay for it somewhere down the line.

The Electrolux 3-way fridges were not designed for boats, and until recently, there was not a gas one, that was. They use a lot of current on 12 volts, as Viking has discovered, and are normally wired so that they will only come on when the engine is running, as in my camper van. When you stop for the night, you turn on the gas or plug in the shore power.

I would always look at the wattage of the fridge before you choose one. If it is more than about 40 watts, you are going to need battery capacity.

Tell me about it.I missed my ferry. Last night of holiday, caravan full of wet awning, fridge full of French cheeses. Decide to hotel it. Park Car and Caravan in clock square in Calais, forget to switch to gas. I used to tow with a 4.2 Daimler. Next morning the battery was so flat the clock had stopped. Won't bore you with the AA, new battery etc, managed to get on a Hovercraft late afternoon. It was a large Electrolux 3 way.

[ChrisB]

PS. Cheese was fine. Wine was poison. Why do some wines taste great on a Med camp site and awful in the UK.

[grendel]

they dont travel well?

[DaveB]

Very recently we changed from a three way fridge to a 240 domestic under counter from Currys at £99, with a 2.5kW inverter and a 480amp hr battery bank along with a 120amp alternator running a sterling digital regulator we can quite happily sit for 2-3 days without running the engine and still have plenty of ice for the g n t's ! 

And even better, with some very careful shopping the whole shebang came in at just under 650 most of which were the batteries that needed replacing anyway!

 

[ChrisB]

That sounds a very good set up Dave on a large boat. However not really an option for the Originator who has an outboard powered V23 or myself with a V20. 4 X 120Ah Batteries would lower the freeboard alright! And make getting on and off easier!

[Jocave]

I've already got one similar to the one linked, we plug it in to the mains the night before then put a few of those frozen ice blocks in then plug it in to the car on the journey up, its good for a day or two but want something I can leave on for a few days, the compressor type ones are very low on power draw but a bit pricey for what they are, still if it keeps the wine and bacon chilled then its worth it, I'm going to measure the space I have and see if I can fit this one in

http://www.jacksonsleisure.com/caravan-motorhome/cool-boxes/electric/dometic-mobicool-fr35-31l-portable-compressor-fridge-freezer-12v-24v-230v/

[DaveB]

1 hour ago, ChrisB said:

That sounds a very good set up Dave on a large boat. However not really an option for the Originator who has an outboard powered V23 or myself with a V20. 4 X 120Ah Batteries would lower the freeboard alright! And make getting on and off easier!

Ah, yes, could be a slight problem there !

[Viking23]

57 minutes ago, Jocave said:

I've already got one similar to the one linked, we plug it in to the mains the night before then put a few of those frozen ice blocks in then plug it in to the car on the journey up, its good for a day or two but want something I can leave on for a few days, the compressor type ones are very low on power draw but a bit pricey for what they are, still if it keeps the wine and bacon chilled then its worth it, I'm going to measure the space I have and see if I can fit this one in

http://www.jacksonsleisure.com/caravan-motorhome/cool-boxes/electric/dometic-mobicool-fr35-31l-portable-compressor-fridge-freezer-12v-24v-230v/

If you can still get one, it is marked as discontinued, maybe the low price was to clear remaining stock. I must admit, last week I was seriously looking at that one, should I need a new one.

Might be worth a phone call, they might keep an odd one back for warranty exchange.

Richard

[ChrisB]

I have just returned from refueling the boat. I switched on the fridge and the draw was 4.4A.

[Viking23]

Just now, ChrisB said:

I have just returned from refueling the boat. I switched on the fridge and the draw was 4.4A.

Hi Chris, will that now be 24/7 if left on, or is there a thermostat that reduces the average current.

On a hot day it will run longer, but if the on time is less than 50 % than that will be good.

Trouble is, it may not be easy to know when the compressor is running. 

 

For a valid experiment, you would need to know the ambient temperature, fridge temperature, on and off time during the day... and night lol. 

Fridge efficiencies have really improved over the last few years.

Richard

[ChrisB]

It has a thermostat, which I set at about half way. If on full it starts freezing things and drinks are too cold. I must admit it does not run that much overnight when left shut but when it does start it disturbs me. 

They (Viking) moved the fridge at the end of 2007 from under the port V berth to under the sink on the V20 probably because of the noise. Except that sites it next to the oven, not clever design where current consumption is concerned.

One of my main reasons for going Honda when I bought the boat was the remote 15 & 20hp still had manual start as backup because of this I just run both 100ah batteries in parallel, breaker set to 1+2 the whole time. I have also converted the four downlighters to LED as well as the Nav Lights and have not had any problems.

I think mine is called a CRP40 and in the bumf it says at +43c it will hold -18c in the freezer and between +5 to + 7c in the fridge bit. Bet at +43c it would be going almost without a break though.

 

[ChrisB]

Another tip that other OB powered owners may find useful:

I moor at Stalham, when I am on my way home from somewhere I switch the fridge off as I pass or leave Fleet Dyke or Ranworth Dam. The new type Honda 15 & 20s have a 12 amp charging coil so in the 2 hours it takes to reach Broadsedge it "puts some back".

With regards to the BM1 Battery Monitor I have it set at 10C because even in summer in my low battery locker it will not reach an optimum 20C. After the batteries first birthday I reset their capacity to 85%, so 170 ah and on their third birthday to 75% or 150 ah not the 200ah they are rated. That way when the instrument does it's various capacity calcs it is cautious.

The above has never let me down in the 10 seasons I have had this boat.

[Guest]

On 22/07/2017 at 9:43 AM, DaveB said:

Very recently we changed from a three way fridge to a 240 domestic under counter from Currys at £99, with a 2.5kW inverter and a 480amp hr battery bank along with a 120amp alternator running a sterling digital regulator we can quite happily sit for 2-3 days without running the engine and still have plenty of ice for the g n t's ! 

And even better, with some very careful shopping the whole shebang came in at just under 650 most of which were the batteries that needed replacing anyway!

 

On my old narrow boat I used to have a mains fridge n it worked perfectly well , the boat had all the other components that yours has ie big alternator etc as has my current boat , so based on the fact its worked before and its currently working for you Dave then out comes the old 2 way fridge and in goes a 230v one .

Just think you got all that equipment for the price of a single 12v fridge and now you can relax because your battery's are being treat to a proper charging requiem and will last much longer  

[Vaughan]

There is no reason why 230v fridges should not be installed in a boat but consider two things :

1/. Good ventilation at the back, to get rid of the heat from the refrigeration process. (ambient temperature and all that)

2/. Permanent running of a 230v appliance with a (large) 2.5 KW inverter requires a properly installed circuit within the boat, especially with regard to earthing, if you are not plugged in to shore power. You will almost certainly need to check and change sacrificial anodes very regularly, to avoid corrosion of stern gear and skin fittings.

[VetChugger]

I had the smallest Waeco fridge which, size wise, was the replacement for the very common Electrolux. It had what they called an "accumulator". This was simply a block around the freezing compartment that froze during the day. Press a button and the motor would not run again until the block had thawed.

Always seemed to last until the moring. Best fridge I have had but not at all cheap and simply too small when I moved to larger boats and increased my onboard beer drinking capacity!

 

[finny]

I bought an isotherm 49 fantastic little fridge .we looked at the coolbox type but it is honestly sometimes better to just up the budget - even got ice on tap for the night cap 

finny