12volt or mains fridge 2017 figures

[mrsmelly]

Ok peeps so I am NOT an electrician but I am someone with approaching 30 years liveaboard status much of it off grid. I have had gas, 12 volt and mains fridges over the years and though I like gas its not much of an option these days so looking at electric I have preffered in the past my mains set up on last boat but one. I bought this boat 2 and a half years ago with 12 volt danfoss usual size undercounter frodge fitted which has worked faultlessly but I wanted something a bit bigger and I have decided again to go back to mains the main reasons being choice, availability and I hate the rip off 12 volt prices so I did much online checking and bought a mains delivered for 160 quid with the lowest consumption figures I could find rather than appliance price. To sum up the build quality is vastly superior and the extra space great, now the important consumption figures. I am not anal but am confined to the boat so have more time than usual to mess around and here goes. My 12 volt fridge drew 3.7 amps when running, this mains fridge draws 4.8 amps including inverter which I would be happy with anyway due to its superior space and quality HOWEVER I timed the 12 volt fridge for a couple of days roughly and I have done the same with this new fridge and to maintain a similar temperature the 12 volt fridge ran very nearly twice as long in each hour as this new fridge does so without being a mathmatician and being super anal it shows without question that the mains fridge is cheaper to run as well as being much nicer. I think domestic fridges have probably been improved recently but remember that my last mains set up wasnt much hungrier than the 12 volt would have been. Ok so you need a decent quality inverter but many of us have those fitted now anyway. Oh and the fridge is virtualy silent. Just sayin like.

[rusty69]

Hoorah, cold beers again. 

 

Out of interest, did they both turn on/off the same amount do you reckon? 

[mrsmelly]

Just now, rusty69 said:

Hoorah, cold beers again. 

 

Out of interest, did they both turn on/off the same amount do you reckon? 

Now you didnt read it did you tsk tsk  the mains fridge runs nearly half as long as the 12 volt did...............

[David Schweizer]

Without identifying the makes and models of each fridge, it is difficult to make any realistic observations. However, the 12v Shoreline we had in Helvetia did not use anything like as much power as yours apparently did. and it was virtually silent. The down side was, as already suggested, the initial purchase price, but as we did not have a big enough inverter, the combined cost of a 230v fridge and a bigger inverter would have probably been more than the 12v fridge (purchased on a Midland Chandlers "Freaky Friday") The other downside was internal storage space which was not brilliant, but many modern 230v fridges aren't that roomy either

Edited July 3, 2017 by David Schweizer

[mrsmelly]

2 minutes ago, David Schweizer said:

Without identifying the makes and models of each fridge, it is difficult to make any realistic observations. However, the 12v Shoreline we had in Helvetia did not use anything like as much power as yours apparently did. and it was virtually silent. The down side was, as already suggested, the initial purchase price, but as we did not have a big enough inverter, the combined cost of a 230v fridge and an inverter would have probably been more than the 12v one (purchased on a Midland chandlers "freaky Friday") The other downside was internal storage space which was not brilliant, but many modern 230v fridges aren't that roomy either

My other 12 volt fridges have all drawn similar so I am suprised. They are all fitted with 12volt danfoss gubbins are they not? Yes you do have to have a decent inverter fitted but Hobby boating and Living aboard are totaly different in every way so it proves to me as a liveaboard of much standing that quite simply mains fridges today are better for a liveaboard of course it will wear the inverter out also but living aboard has always been more expensive than living in a house so its all part of it.

[rusty69]

Just now, mrsmelly said:

Now you didnt read it did you tsk tsk  the mains fridge runs nearly half as long as the 12 volt did...............

I did read it honest. 

"12 volt fridge ran very nearly twice as long in each hour "

The 12V one could have come on 5 times say for 4 minutes each =20 mins

The 240v one coud come on 2 times for 5 minutes =10 minutes

So it turned on/off less, so less startup current. 

 

[mrsmelly]

Just now, rusty69 said:

I did read it honest. 

"12 volt fridge ran very nearly twice as long in each hour "

The 12V one could have come on 5 times say for 4 minutes each =20 mins

The 240v one coud come on 2 times for 5 minutes =10 minutes

So it turned on/off less, so less startup current. 

 

Ahhhhggghhhh Ok so to sum up in any 24 hours the 12 volt fridge was running nearly twice as long. Look keep buying numpty 12 volt equipment if you want to I dont care 

[Chewbacka]

I've done the same and run a 240V fridge from my inverter.  HOWEVER if your inverter does not have a low power sleep mode - mine does - and assuming you leave the inverter on most of the time - otherwise how can the fridge start and stop when it needs to - then you need to add on to your consumption figures the time the inverter is in doing not very much.  Which given you said the mains fridge runs half the amount of the 12v fridge indicates to me about 40 mins per hour no load and 20 mins per hour fridge running.  If yours is an efficient inverter but with out sleep mode the inverter is possibly using 1A when in idle.  Which over 24hours would be equivalent to 16 hours (2/3 of the time the fridge is off) which is another 16Ahrs.  - Just something to think about.

[rusty69]

2 minutes ago, mrsmelly said:

Ahhhhggghhhh Ok so to sum up in any 24 hours the 12 volt fridge was running nearly twice as long. Look keep buying numpty 12 volt equipment if you want to I dont care 

I use a 240v chest freezer as a fridge 

[mrsmelly]

Just now, Chewbacka said:

I've done the same and run a 240V fridge from my inverter.  HOWEVER if your inverter does not have a low power sleep mode - mine does - and assuming you leave the inverter on most of the time - otherwise how can the fridge start and stop when it needs to - then you need to add on to your consumption figures the time the inverter is in doing not very much.  Which given you said the mains fridge runs half the amount of the 12v fridge indicates to me about 40 mins per hour no load and 20 mins per hour fridge running.  If yours is an efficient inverter but with out sleep mode the inverter is possibly using 1A when in idle.  Which over 24hours would be equivalent to 16 hours (2/3 of the time the fridge is off) which is another 16Ahrs.  - Just something to think about.

Yes I completely agree thats why I said you need a quality inverter not some stirling type crap. My verter draws 0.3 of an amp when switched on without draw. My mastervolt used to draw 0.5 and victron draw about 0.7 if I recall. All in all the mains is still better in my opinion of course.

2 minutes ago, rusty69 said:

I use a 240v chest freezer as a fridge 

[Chewbacka]

1 minute ago, mrsmelly said:

Yes I completely agree thats why I said you need a quality inverter not some stirling type crap. My verter draws 0.3 of an amp when switched on without draw. My mastervolt used to draw 0.5 and victron draw about 0.7 if I recall. All in all the mains is still better in my opinion of course.

I was making the point more for others that were thinking of going the same route, but using some cheap, rubbish inverter with a fairly high quiescent current and then wondering why they were not getting the power saving they expected.  My inverter uses 16W when idle which is quite high, but drops to 1.2W in sleep mode, however even a tv in standby will keep it awake, so I am quite anal about switching off sockets when the item is not required.

[mrsmelly]

2 minutes ago, Chewbacka said:

I was making the point more for others that were thinking of going the same route, but using some cheap, rubbish inverter with a fairly high quiescent current and then wondering why they were not getting the power saving they expected.  My inverter uses 16W when idle which is quite high, but drops to 1.2W in sleep mode, however even a tv in standby will keep it awake, so I am quite anal about switching off sockets when the item is not required.

Yes I do agree that the inverter is realy key to this whole process. I had a sterling fitted on my last boat when I bought it  blimey it needed its own battery bank just to power it!! I sold it on fleabay and bought a mastervolt again. The verter on this boat however is even better consumption wise than good old mastervolt. I carry a new mastervolt in my spares for when this one goes tits up.

[Dave_P]

14 minutes ago, mrsmelly said:

Yes I completely agree thats why I said you need a quality inverter not some stirling type crap. My verter draws 0.3 of an amp when switched on without draw. My mastervolt used to draw 0.5 and victron draw about 0.7 if I recall. All in all the mains is still better in my opinion of course.

What inverter do you have?

[mrsmelly]

4 minutes ago, Dave_P said:

What inverter do you have?

Its a power master. Trouble is they are no longer imported to the uk and there is no uk distributor, they are simply awesome. It was fitted by the builder who had this built for his own use and as he owned a hire fleet he specced it well but told me he was dismayed because he can no longer get this equipment for his own or his hire fleet. He has however sold up now so it will not matter to him anymore.

[rusty69]

19 minutes ago, mrsmelly said:

Its a power master.

I got a power master years ago as a cheap throw away inverter (probably not the same manufacturer as yours). Its still going, 10 yesrs on

[mrsmelly]

Just now, rusty69 said:

I got a power master years ago as a cheap throw away inverter (probably not the same manufacturer as yours). Its still going, 10 yesrs on

Just looking online at prices and even good stuff like victron that are quite good now have come down in price by the looks of things.

[cuthound]

I suspect it is all down to the quality of the insulation used on both fridges. 

Modern fridges have excellent insulation compared to those made just a few years ago.

How old is your 12 volt fridge? 

Presumably a brand new 12 volt fridge would use a modern case,  and thus come with better insulation. 

[Dave_P]

Tim did you calculate how many ah per day were taken by either the 240v or the 12v?

[mrsmelly]

4 minutes ago, Dave_P said:

Tim did you calculate how many ah per day were taken by either the 240v or the 12v?

I have a button jobby on the nasa that tells me but it was more timing of how long compressor was running that i measured.

[mrsmelly]

28 minutes ago, cuthound said:

I suspect it is all down to the quality of the insulation used on both fridges. 

Modern fridges have excellent insulation compared to those made just a few years ago.

How old is your 12 volt fridge? 

Presumably a brand new 12 volt fridge would use a modern case,  and thus come with better insulation. 

I dont know how old the 12 volt was but its still going strong another forum member has it. To digress a little my bro in law also a liveabord had a shoreline 12 volt for for several years on his boat and it went tits up 2 and a half years ago so he bought another new shoreline. He told me this week that its build quality is crap and not near as good as his older one and is falling to bits and funnily enough talking to a local liveaboard who also has a 12volt shoreline who tells me the same story. I do think they have probably all improved re insulation but everything about this mains fridge  is way better built.

[smileypete]

On 03/07/2017 at 12:04, rusty69 said:

I use a 240v chest freezer as a fridge 

Any ideas how much juice it uses?

I'm running the freezer compartment inside my fridge, as a fridge, which is seemingly working quite well.

Stuff in the 'fridge' is about 2 to 5°C, and rest of the fridge is about 12 to 15°C which should be OK enough for salads, veg, eggs, bread, maybe butter/marg too.

Have set it to run on a segment timer for 20 mins every 2 hours, so it's averaging around 20W - not bad for an ancient (read v. inefficient) mains fridge.

 

[rusty69]

18 minutes ago, smileypete said:

Any ideas how much juice it uses?

I'm running the freezer compartment inside my fridge, as a fridge, which is seemingly working quite well.

Stuff in the 'fridge' is about 2 to 5°C, and rest of the fridge is about 12 to 15°C which should be OK enough for salads, veg, eggs, bread, maybe butter/marg too.

Have set it to run on a segment timer for 20 mins every 2 hours, so it's averaging around 20W - not bad for an ancient (read v. inefficient) mains fridge.

 

It takes a fair amount , 12A (including inefficient inverter) when running,but it is 60l. It runs through the inverter whilst batteries are charged with solar(1000W) from Mar-Oct, then reverts to freezer use for the other months.

Edited July 4, 2017 by rusty69

[mross]

You do need to store certain foods at 4° C to prevent bacteria growth.  https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm093704.htm

[rusty69]

21 minutes ago, mross said:

You do need to store certain foods at 4° C to prevent bacteria growth.  https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm093704.htm

Mine has a programmable thermostat that keeps food between 0 and 4 degrees C(or whatever you set it to) , so no worries.

Edited July 4, 2017 by rusty69

[OldGoat]

15 minutes ago, mross said:

You do need to store certain foods at 4° C to prevent bacteria growth.  https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm093704.htm

Yee-Haa - that's an American site, I thought over here 6 degrees C was the recommended - at least that's what our posh home fridge defaults to. Most (?) thermostats are towards the top of the fridge, so things at the bottom are a bit colder anyway...