Lowest power consuming 12v fridge

[Spacebar]

It seems either way I go the cost will be £500 or more all in.

A 12v fridge £500 and use my existing inverter for my other bits or a cheaper fridge and new higher power inverter!

Does it need to be pure sine wave to run a fridge?

[MoominPapa]

Taking in to account start up current for the compressor, what is the smallest output invertor that would run a 240v fridge?

The start-up current is going to be the killer. Our new Bosch A+ 240v fridge pulls about 70A from the batteries via a true sine wave inverter when it starts up. Running, its a tenth of that and it spends most of its time not running. Our 1.8kW inverter has a power-save mode where it shuts down is nothing is using juice, and checks every second or so in case something has been switched on. That reduces the standing inverter power use from about an amp to 50mA or so. It took me a long time to get this to work, it turns out there something in the washing machine that confuses it, even when the washing machine is off. You have to turn the switch on the socket off when the WM is not in use and then it's fine.

 

MP.

Edited May 28, 2011 by MoominPapa

[Graham Bowers]

Why will you only have solar to charge with, if using a petrol outboard?

 

We have a 10HP Honda outboard and it charges at 6A, as I remember. Not a huge current, but if we cruise 4 hours a day we can run our 12V shoreline chest fridge for 14 hours a day - we switch it off at night to keep it quiet. We have a single leisure battery.

 

Cheers

Graham

[Robin2]

Many many thanks Roger for taking the time.

At present I have a 300w inverter in my van would that be ok with the small fridge you mention?

I would simply turn off the inverter too as my tv will be 12v and everything else.

Mobile and lap top will be plugged into inverter when needed probably when fridge is running.

Seems like I may well need to consider a little genny too incase.

Thanks again.

 

No.

 

I suggest 1000W. I have a 600W Sterling quasi sine wave inverter and it could not cope with my fridge freezer. In spite of its supposed protection from overloads and a much larger than 600W surge capacity it has failed twice and Sterling have been kind enough to replace it. I now have a Maplin 1000W inverter which seems to be coping. The fridge seems to have a penchant for stalling at startup and drawing about 45 - 50 amps at 12v until its own cut-out kicks in. This also presents a challenge to a small battery that is well discharged - the voltage may fall below the inverter's minimum. The under-voltage alarm woke me in the early hours a few times while I was dithering about getting more batteries.

[mchancox]

It seems either way I go the cost will be £500 or more all in.

A 12v fridge £500 and use my existing inverter for my other bits or a cheaper fridge and new higher power inverter!

Does it need to be pure sine wave to run a fridge?

I would go for a small Waeco model that runs from 12v rather than a 230v fridge that you have to run from an invertor.

Taking a step back, if you look at where your power is coming from, for a 230v fridge you would be using battery power to power the invertor to power the fridge. It would be best to use a PSW invertor to prevent premature failure of the electronic components in the controls for the fridge, thus hiking up the price. Some invertors consume power even when they are not attached to a load which is called a parasitic drain. Plus the introduction of another component introduces yet more things to go wrong.

If you run a good quality fridge from a 12v supply you may well find that your power consumption is less overall than the 230v option. Without confussing the issue and introducing mathematics and science, if the choice was mine I would go for a 12v fridge.

[nb Innisfree]

looking at the equivalent 240v version of our Lec 12/24v fridge it states somewhere in the region of 150kwh per annum consumption, this equates to somewhere in the region of 17ah @24v per 24hrs, our fridge appeared to use just over 16ah after I monitored it, slightly more efficient maybe but I guess in practice they are equal, our Victron 3kva PSW is quoted as 94% efficient and my observations seem to agree with that throughout it's output range. So for us it will be a cheaper 240v model next time, one extra ah or two per day is going to be no problem for us especially as we leave the inverter on 24/7

[Robin2]

It seems either way I go the cost will be £500 or more all in.

A 12v fridge £500 and use my existing inverter for my other bits or a cheaper fridge and new higher power inverter!

Does it need to be pure sine wave to run a fridge?

 

Sorry, I didn't see this earlier.

 

My fridge runs happily from a quasi sine wave inverter. I could not afford the idle current of my big pure sine wave inverter and the fridge did not work properly when the inverter was in its power-save mode. And, of course, other small appliances (eg AA battery charger) would not draw enough power to bring the big inverter on line.

 

 

Without confusing the issue and introducing mathematics and science, if the choice was mine I would go for a 12v fridge.

 

 

I think a better way to put this would be "Don't confuse me with the facts"

[nb Innisfree]

Sorry, I didn't see this earlier.

 

My fridge runs happily from a quasi sine wave inverter. I could not afford the idle current of my big pure sine wave inverter and the fridge did not work properly when the inverter was in its power-save mode. And, of course, other small appliances (eg AA battery charger) would not draw enough power to bring the big inverter on line.

 

 

Our quality PSW use very little on idle (about 0.6 amps @ 24v) so I don't need it in standby and therefore it is available for any load be it small or large, as we always have something on such as a 240v bedside LED clock projector and phone charging etc our inverter stays very efficient.

[wrigglefingers]

I have an Isotherm which consumes very little - I reckon about 1.3A on average which is very close to their claim of 1.2A for a 130L. Ely Chandlers had the best price for it. It was expensive and it's not got the most robust fittings but it is very efficient and runs very quietly. They do the same fridge with cold storage plates but after a brief discussion we all decided that eight cans of beeer would do the same job ....

[FadeToScarlet]

I suppose if you already have a big decent inverter, a cheaper 230v fridge might be more cost efficient, but as we don't, we chose a Shoreline which claims something like sub 20ah per day.

[Nickhlx]

We too have a Victron Combi Inverter ( 12/3000/120/16) and I am sure I read somewhere that the efficiency is around 94-96% and the standby / quiescent power consumption is 0.8 amps. With "normal" activity it is on anyway for at least 12 hours a day and the engine is running for at least half that, so at worst it accounts for about 10 amp hours a day, which from our domestic bank is not a great amount ( 2%)

 

We did go for a 12 volt fridge option though as was recommended, and it does mean we can switch the inverter off at night - it does also allow the Combi to be set to "Charger only" when on the shoreline. This means that if the shoreline trips out, the inverter does not fire up and drain the batteries, although we avoid leaving any power drain on if we are not there for more than a few hours.

 

Nick

Edited May 31, 2011 by Nickhlx

[FadeToScarlet]

We too have a Victron Combi Inverter ( 12/3000/120/16) and I am sure I read somewhere that the efficiency is around 94-96% and the standby / quiescent power consumption is 0.8 amps.

 

Whereas Shoreline claim that that's roughly the power consumption of my fridge

 

http://www.boatfridge.com/index.asp?Col_Category=Fridges+%2D+Narrow&Col_SubCategory=&Col_SubCategory2=&display=main&productID=171

[Nickhlx]

Whereas Shoreline claim that that's roughly the power consumption of my fridge

 

http://www.boatfridg...n&productID=171

 

 

Noted - which is partly why we also went with a 12V Waeco.

 

My point though was that the efficiency of some / all / Victron PSW inverters is somewhat better than 90 % and that the "overhead" of that inefficiency could/should be shared with other mains consuming devices. For those who prefer to have mains everything ( TV / Microwave / Fridge / Hoover / freezer ) was that the "inefficiency" need not be very dramatic.

 

Nick

[Spacebar]

Thanks for all the replies.

Is there no way I could have a gas run fridge venting outside at the opposite end to the petrol engine?

This to me seems far more efficient than messing around with batteries,inverters 12v fridges ect.

I just need a little box to keep milk cold and cheese lol.

This is the biggest hurdle on the boat over anything!

[Gunna Do]

We used to have a smallish chest fridge from Combicool on our yachty thing. It ran on mains/12v or gas. The first 2 were non starters for us but gas was brilliant. It used next to no gas and would even freeze stuff if you turned the control much above 1/2 way. I don't see why one of these could not be used out in the cratch area (assuming you have this and gas of course!) as most have low level drains to comply with the regs. We seriously thought about using ours out there but are a bit tight for space and have a 12v fridge anyway.