12v or 240 A+ Fridge

[Redeye]

 

Quattro uses around 25w in zero load power is thats an extra 50ah/day for the inverter.

 

Install a 24V fridge and the Quattro will still use 25W. Pointless arguement, the inverter is always on.

 

I really like my Bosch fridge

[Ex- Member]

 

http://www.indelwebastomarineusa.com/Products/graphics/DS_IWM_CruiseFridges_EN_2010.pdf

 

They're manufacturers figures non verified. Verified comes with one of these.

 

http://savvyscot.com/top-money-saving-tips-for-appliances/

 

Install a 24V fridge and the Quattro will still use 25W. Pointless arguement, the inverter is always on.

 

I really like my Bosch fridge

 

We do too

 

http://www.rgbdirect.co.uk/Products/Appliances/Fridges/BOSCH/KTR18P20GB

 

http://www.ebay.co.uk/itm/bosch-logixx-ktr18p20gb-fridge-/141238500561?pt=UK_Home_Garden_Kitchen_Fridges_Freezers&hash=item20e2787cd1

Edited April 1, 2014 by Julynian

[Staarek]

 

Can you provide make / model?

 

It was some time ago so I cannot remember exactly, but it was bought of ebay. I'll have a look though.

[Robbo]

 

Install a 24V fridge and the Quattro will still use 25W. Pointless arguement, the inverter is always on.

 

I really like my Bosch fridge

 

Pointless? If the only need for the inverter to be on 24/7 is for the fridge then it's hardly pointless!

 

The point is that fridges are roughly the same efficiency whether 12v or 240v, it's the inverter losses that count as these can more than double the amount of ah's used. If you use the inverter 24/7 for other stuff then its not really an argument.

I think the inverter loss argument is now irrelevant.

 

It's the the main argument, inverter losses is the main issue especially if using 24/7 purely for the fridge.

Edited April 1, 2014 by Robbo

[ditchcrawler]

 

http://www.ebay.co.uk/itm/bosch-logixx-ktr18p20gb-fridge-/141238500561?pt=UK_Home_Garden_Kitchen_Fridges_Freezers&hash=item20e2787cd1

Dam that is just down the road from me, but I am off in the morning. The door seal has gone on my 12 year LEC

[Jambo]

 

120Kwh/yr = 328wh/day / 93% for inverter losses = 352.7wh/day + 240wh/day for inverter = 592.7wh = 49.4ah/day

65Kwh/yr = 178wh/day / 93% for inverter losses = 191.4wh/day + 240wh/day for inverter = 543.7wh = 45.3ah/day#

 

Conclusion: 12v fridge uses less power especially if you don't need a large fridge (25ah/day), but the larger the fridge the more losses of the inverter become minor.

 

Note my inverter calcs are for a Victron multiplus in AES mode (10w), but you can add another 10amp to the figures for normal mode (15w).

 

Your calculation went awry in the second case.

 

Also are you sure you should count the AES mode consumption and the efficiency of the inverter? Surely the AES mode is for when it's under no load and the efficiency accounts for any losses and consumption within the inverter when it's under load?

 

If your inverter is solely used to power the fridge then I can see that the distinction isn't likely to be very great and a 12V fridge is probably the right way forwards (although as pointed out above I'd really like to see some proper bench tests to verify the manufacturers' numbers for 12V fridges).

 

We only use 12V for lighting and have the telly, laptops and wifi running off the inverter as well so I attribute a good chunk of the inverter consumption to them.

[Ex- Member]

 

Pointless? If the only need for the inverter to be on 24/7 is for the fridge then it's hardly pointless!

 

The point is that fridges are roughly the same efficiency whether 12v or 240v, it's the inverter losses that count as these can more than double the amount of ah's used. If you use the inverter 24/7 for other stuff then its not really an argument.

 

It's the the main argument, inverter losses is the main issue especially if using 24/7 purely for the fridge.

 

You,e quoted that out of context.

 

I think the inverter loss argument is now irrelevant. All you need to do is fit enough solar to cope with actual 240v fridge use/consumption and inverter losses. Even if you buy a fridge + 200w of solar and a small inverter to run it, that's still going to be cheaper than many 12v fridges.

[Robbo]

 

Your calculation went awry in the second case.

 

Also are you sure you should count the AES mode consumption and the efficiency of the inverter? Surely the AES mode is for when it's under no load and the efficiency accounts for any losses and consumption within the inverter when it's under load?

 

If your inverter is solely used to power the fridge then I can see that the distinction isn't likely to be very great and a 12V fridge is probably the right way forwards (although as pointed out above I'd really like to see some proper bench tests to verify the manufacturers' numbers for 12V fridges).

 

We only use 12V for lighting and have the telly, laptops and wifi running off the inverter as well so I attribute a good chunk of the inverter consumption to them.

 

Cheers I've updated my mistake ....

 

65Kwh/yr = 178wh/day / 93% for inverter losses = 191.4wh/day + 240wh/day for inverter =431.4wh = 36ah/day

 

You,e quoted that out of context.

 

I think the inverter loss argument is now irrelevant. All you need to do is fit enough solar to cope with actual 240v fridge use/consumption and inverter losses. Even if you buy a fridge + 200w of solar and a small inverter to run it, that's still going to be cheaper than many 12v fridges.

 

Still not out of context if you need to find an extra 50ah/day to power a inverter.

[Ex- Member]

 

Cheers I've updated my mistake ....

 

65Kwh/yr = 178wh/day / 93% for inverter losses = 191.4wh/day + 240wh/day for inverter =431.4wh = 36ah/day

 

Still not out of context if you need to find an extra 50ah/day to power a inverter.

 

You clearly can't comprehend

[Robbo]

 

You clearly can't comprehend

 

50ah's is alot, and solar is only really beneficial for 5 months of the year.

[Jambo]

Where does the 50Ah come from? That's ~600Wh

 

Assuming your inverter calcs above are right (and I'm still slightly dubious) then it comes to 20Ah.

 

ETA: Oh I see it's in reference to the Quattro inverter.

Edited April 1, 2014 by Jambo

[Redeye]

 

Pointless? If the only need for the inverter to be on 24/7 is for the fridge then it's hardly pointless!

 

The point is that fridges are roughly the same efficiency whether 12v or 240v, it's the inverter losses that count as these can more than double the amount of ah's used. If you use the inverter 24/7 for other stuff then its not really an argument.

 

It's the the main argument, inverter losses is the main issue especially if using 24/7 purely for the fridge.

 

The only problem is that I never said the inverter was only on for the fridge ...... The inverter is always on, it powers the diesel heating system 240V, a number of occasional lamps, the clock on the oven and various charging applications for phones and tablets that modern families seem to accumulate. The battery system is sized to accomodate and as is the alternator.

 

and I still really like my Bosch fridge

 

[Robbo]

Where does the 50Ah come from? That's ~600Wh

 

Assuming your inverter calcs above are right (and I'm still slightly dubious) then it comes to 20Ah.

 

It's the zero power load for a Quattro at 25watt.

 

I used 10 watt for the inverter calc as it's seems to be the middle ground. The lowest I've seen (not much research I may add) is 6watt, with the Quattro the highest at 25watt.

[Robbo]

 

The only problem is that I never said the inverter was only on for the fridge ...... The inverter is always on, it powers the diesel heating system 240V, a number of occasional lamps, the clock on the oven and various charging applications for phones and tablets that modern families seem to accumulate. The battery system is sized to accomodate and as is the alternator.

 

and I still really like my Bosch fridge

 

 

 

But your not the OP and if you read my conclusion you will see that I said the bigger the fridge the less the inverter losses become apparent. You obviously have alot of 240v equipment, for you a 240v fridge makes sense.

 

Your fridge is a £380 fridge, it should be good, the equivalent size 12v fridge is around £675. If you didn't have or need the inverter the 12v fridge would be a better choice.

 

For info, I'm refitting my boat and looking at 240v diesel heating so a 240v fridge is the better option for me as well. (Already have a decent low zero-load wattage inverter).

Edited April 1, 2014 by Robbo

[Phil Ambrose]

Dam that is just down the road from me, but I am off in the morning. The door seal has gone on my 12 year LEC

Why not just buy a new seal? Interesting to note that it has been suggested that somehow a 12v fridge is inferior when in fact in all probability they are eouipped with a Danfos compressor which is a bench mark bit of kit. Having a super styled 240v fridge makes no odds to how it works ie to keep things cold. My Shoreline fridge is 110litre capacity and my Shoreline freezer is 80litre capacity yes they are LEC, yes they just look like white boxes but they work!

Also 300watts of PV array run them for 8 months of the year (not 5 months)

We have lived aboard for 14 years and have made plenty of mistakes but going 12 volt wasn't one of them.

Phil

[Paul C]

 

You,e quoted that out of context.

 

I think the inverter loss argument is now irrelevant. All you need to do is fit enough solar to cope with actual 240v fridge use/consumption and inverter losses. Even if you buy a fridge + 200w of solar and a small inverter to run it, that's still going to be cheaper than many 12v fridges.

 

When I compared 240V fridges to 12V, I took into account the cost of generating electricity by diesel engine and the additional capital cost of extra solar power required, if the 240V route was chosen. It comes down to capital cost vs running costs, yes solar is good long term but of course there is a capital cost element and you need to do a proper analysis using this figure too. It depends what you call a reasonable/relevant "time period" to assess things over. And you'd need to know the power consumptions of each, quite accurately, since you're comparing the difference between two similar things.

 

Based on my calcs from a few years ago, we went down the 12V route. I appreciate that if there's other items which need 240V then you can offset or apportion the cost of a large/expensive inverter to favour a 240V fridge though.

 

So its not clear cut but for many, 12V fridge will be better. For some, 240V is better.

[ditchcrawler]

Why not just buy a new seal?

Its about the only one that is not available.

[Ex- Member]

 

When I compared 240V fridges to 12V, I took into account the cost of generating electricity by diesel engine and the additional capital cost of extra solar power required, if the 240V route was chosen. It comes down to capital cost vs running costs, yes solar is good long term but of course there is a capital cost element and you need to do a proper analysis using this figure too. It depends what you call a reasonable/relevant "time period" to assess things over. And you'd need to know the power consumptions of each, quite accurately, since you're comparing the difference between two similar things.

 

Based on my calcs from a few years ago, we went down the 12V route. I appreciate that if there's other items which need 240V then you can offset or apportion the cost of a large/expensive inverter to favour a 240V fridge though.

 

So its not clear cut but for many, 12V fridge will be better. For some, 240V is better.

 

Well calculations made 2 years ago are irrelevant now with solar available so cheaply. Even If I didn't want any other 240v I would still buy a 240v fridge but only buy an inverter with the output the fridge requires. Even with the cost of a quality fridge and inverter, you would still have enough change to buy 200w of solar which would adequately supply power for the fridge and inverter.

 

Also we have installed enough solar so we can rely on it from mid March to Mid/end October which is 7 months. We haven't needed any additional charging for 3 weeks now. I reckon 200w of solar would do the same for a fridge.

 

Overall the benefits of 240v is clear.

 

Superb efficiency.

Very cheap initial cost.

A vastly better choice of fridge design.

Much cheaper to replace a 240 unit should it fail outside of warranty.

You end up with a 240v supply, which will always come in handy for other things like charging and smaller leccy items.

You can use the additional money spent on 12v for some solar.

 

I would argue that even if a boat doesn't have an inverter already, that going 240v for a fridge is a far wiser and more beneficial option, especially taking in to account the cost of a 12v fridge.

[Phil Ambrose]

I'm not getting the "better choice of fridge design" thing, to me a fridge is a box with a door which keeps things cold. What more can you ask of it?

Phil

[Ex- Member]

I'm not getting the "better choice of fridge design" thing, to me a fridge is a box with a door which keeps things cold. What more can you ask of it?

Phil

 

A car is metal on 4 wheels, they're not all the same though

[Phil Ambrose]

A car is metal on 4 wheels, they're not all the same though

Yeah they are, they get you from A to B, all that is required.

Phil

[Ex- Member]

Yeah they are, they get you from A to B, all that is required.

Phil

 

Same design!

[Phil Ambrose]

Same design!

?

 

Phil

[TandC]

I run a bog-standard slimline 240v fridge/freezer compartment as our situation puts us on shoreline power for a large chunk of the year so that is a no-brainer. Our 1000w Stirling inverter is there to run in when out cruising, and yes, having an inverter is handy for all those other charging tasks when out and about.

 

Hijack alert:

 

If I were to install some fans to help kep my 240v fridge cool in the summer, would you simply use 12v computer fans from Maplins and install a couple in holes in the wooden floor, drawing the cool air out of the bilge and blowing it straight up into the air space aroudn the back of the fridge?

[Phil Ambrose]

Re the fans, yes you have got it exactly right, that's all you have to do, wire them so they come on when the compressor kicks in.

There have been many threads on this subject, how to do etc so just have a look on the search function.

Phil