Best small inverter to power 240V fridge

[Paul C]

3 hours ago, ditchcrawler said:

But if you don't already have the wiring for a 12 volt fridge then I can be a bit of mucking about adding it as it needs to be thicker than you may think.

And if you don't have mains wiring....including the RCD, circuit breaker, N-E bond, earthing point etc etc

[Sea Dog]

3 hours ago, Mitchellmoxo said:

Thanks for the replies it looks like I will be using the 3kw inverter on board 24/7 rather than having a dedicated one just for the fridge! 

Ooh, you little tinker! You never mentioned you already had a 3kW inverter - it's like watching one of those detective novels whilst wracking your brains over whodunit, only to find it was a long lost brother no-one even knew about til the last 5 minutes! 

Next time you post I'm not gonna read it til page 3! 

[Boater Sam]

I have toyed with an idea to use a modern, more efficient 240v fridge when my Batts 12v finally dies, which I hope is a long way into the future.

If you use a dedicated inverter, 1000w minimum, and locate it near the fridge, you can use the 12v wiring, if it was a decent gauge to start with.

Then, if the fridge stat is a simple mechanical or relay with contacts that you can access, use the stat to switch the inverter on/off switch circuit.

The inverter then only runs when the fridge calls for current. I suspect that a lot of new fridges use an electronic thermistor stat that this won't work with but its easy to insert an old fashioned capillary stat as well.

[Sea Dog]

6 hours ago, Boater Sam said:

I have toyed with an idea to use a modern, more efficient 240v fridge when my Batts 12v finally dies, which I hope is a long way into the future.

If you use a dedicated inverter, 1000w minimum, and locate it near the fridge, you can use the 12v wiring, if it was a decent gauge to start with.

Then, if the fridge stat is a simple mechanical or relay with contacts that you can access, use the stat to switch the inverter on/off switch circuit.

The inverter then only runs when the fridge calls for current. I suspect that a lot of new fridges use an electronic thermistor stat that this won't work with but its easy to insert an old fashioned capillary stat as well.

It's debatable whether a 240v fridge is more efficient, as many 12v fridges are based on well insulated 240v models with perfectly good Danfoss 12v compressors.  Range of choice is an issue and, of course, the additional costs.

By siting the inverter by the fridge, you'd lose the advantage in terms of volts drop brought by 240V and the thinner cables required. Perhaps better to have a return line with the signal to operate the inverter where it ought to be - as close as sensible to your batteries. 

But you're now also buying a dedicated inverter as well as a fridge, plus control circuitry, so your savings in cost have evaporated. 

If you can't have/don't want a decent, suitable 12V fridge, it's gonna hard to beat a single, good quality inverter powering all your needs as well as the fridge.

[Onewheeler]

Might be worth quoting some real figues. The Indesit under-counter fridge I installed last year, A+ rated, draws 65 W with compressor running and a mean consumption of about 15 W. That's in warm to hot French weather. It probably isn't much different from any other similar sized A+ fridge. It runs very happily from a Sunshine Power 1kW PSW inverter.

Martin/

[clv101]

Sorry to drag up this older thread. I've recently added a 300L A++ chest freezer to my off-grid setup, running from my Victron 1200VA inverter. It works, it can start the compressor - however the inverter does make a nasty buzz for half a second and the overload light flashes. It doesn't cut out though.

 

I'm worried the 'buzz' noise indicates this might by bad for the inverter. Why does it buzz? Is it likely to die?

[TheBiscuits]

2 minutes ago, clv101 said:

Sorry to drag up this older thread. I've recently added a 300L A++ chest freezer to my off-grid setup, running from my Victron 1200VA inverter. It works, it can start the compressor - however the inverter does make a nasty buzz for half a second and the overload light flashes. It doesn't cut out though.

 

I'm worried the 'buzz' noise indicates this might by bad for the inverter. Why does it buzz? Is it likely to die?

Startup surge on the fridge is more than your inverter is rated for, but not by enough to make it refuse to start. 

 

If it really is half a second or less, don't panic about it - but you could consider turning the fridge to run a little bit colder so it runs for longer periods (less compressor starts) if your battery bank can support that level of usage.

 

Are you sure it's an overload alarm and not a low input voltage alarm on startup?

[TheBiscuits]

On 22/03/2018 at 02:21, Boater Sam said:

If you use a dedicated inverter, 1000w minimum, and locate it near the fridge, you can use the 12v wiring, if it was a decent gauge to start with.

Just spotted this in a revived thread.  I always work on a 10V rule to allow for inverter losses, so a 1000W inverter will be pulling up to 100A from the batteries.  The fridge had better be mounted in the engine 'ole to pull 100A through random wiring! 

 

Also see the post I just replied to above, where a 1200VA inverter is struggling to start a fridge.

 

I also agree with @Sea Dog above - either get a decent inverter you can afford the amp hours to keep on 24/7 or get a decent 12V fridge.

[WotEver]

11 minutes ago, TheBiscuits said:

Are you sure it's an overload alarm and not a low input voltage alarm on startup?

I strongly suspect it’s the latter. 

[Sea Dog]

17 minutes ago, clv101 said:

Sorry to drag up this older thread. I've recently added a 300L A++ chest freezer to my off-grid setup, running from my Victron 1200VA inverter. It works, it can start the compressor - however the inverter does make a nasty buzz for half a second and the overload light flashes. It doesn't cut out though.

 

I'm worried the 'buzz' noise indicates this might by bad for the inverter. Why does it buzz? Is it likely to die?

If your Victron is a fairly modern Phoenix Compact, its one of their "Sinus Max" versions - check out the manual downloadable from Victron's website to confirm. If it is, these can hack a large starting load, and the 1200w is good for that as a continuous load but can deliver 2400w peak power momentarily.  They do hum a bit when the load comes on.

[mrsmelly]

9 minutes ago, TheBiscuits said:

Just spotted this in a revived thread.  I always work on a 10V rule to allow for inverter losses, so a 1000W inverter will be pulling up to 100A from the batteries.  The fridge had better be mounted in the engine 'ole to pull 100A through random wiring! 

 

Also see the post I just replied to above, where a 1200VA inverter is struggling to start a fridge.

 

I also agree with @Sea Dog above - either get a decent inverter you can afford the amp hours to keep on 24/7 or get a decent 12V fridge.

A decent inverter such as mine only uses 0.3 of an amp when switched on and not powering anything. My stuff is all mains stuff and the inverter is never switched off. All managed very easily from 4 cheapo batteries in fact 3 would do it.

[clv101]

4 minutes ago, Sea Dog said:

If your Victron is a fairly modern Phoenix Compact, its one of their "Sinus Max" versions - check out the manual downloadable from Victron's website to confirm. If it is, these can hack a large starting load, and the 1200w is good for that as a continuous load but can deliver 2400w peak power momentarily.  They do hum a bit when the load comes on.

Yes, that's exactly it. It's quite a hum though!

 

It's not low voltage, it's on a 464Ah@48v battery store with good cables.

[TheBiscuits]

4 minutes ago, clv101 said:

Yes, that's exactly it. It's quite a hum though!

 

It's not low voltage, it's on a 464Ah@48v battery store with good cables.

Then I would say turn the fridge dial a little bit further and don't worry about it.

[ditchcrawler]

31 minutes ago, mrsmelly said:

A decent inverter such as mine only uses 0.3 of an amp when switched on and not powering anything. My stuff is all mains stuff and the inverter is never switched off. All managed very easily from 4 cheapo batteries in fact 3 would do it.

about the same as mine, a Mastervolt 1500 true sine

[mrsmelly]

Just now, ditchcrawler said:

about the same as mine, a Mastervolt 1500 true sine

Yep. This one is a power master 1500 and a brilliant bit of kit that is now unavailable. I have a victron new as a spare if this ever goes down ? But victron ain't as good as master volt or this unit I have but I bought it at a very very good price.

[nbfiresprite]

2 hours ago, mrsmelly said:

A decent inverter such as mine only uses 0.3 of an amp when switched on and not powering anything. My stuff is all mains stuff and the inverter is never switched off. All managed very easily from 4 cheapo batteries in fact 3 would do it.

My prosine 1800i uses less than that on powersave mode. The only noise you hear when inverter wakes up from powersave mode is the fan. 

[MtB]

3 hours ago, TheBiscuits said:

or get a decent 12V fridge.

 

Its not a fridge, its a freezer.

 

Does anyone make a 12v freezer now? I was googling for one the other day and couldn't find one.

[Mac of Cygnet]

34 minutes ago, Mike the Boilerman said:

 

Its not a fridge, its a freezer.

 

Does anyone make a 12v freezer now? I was googling for one the other day and couldn't find one.

 

http://www.penguinfrigo.co.uk/shop/category/front-opening-freezers/  

 

Not much change out of a grand, though (£1.89 to be precise).

[OldGoat]

A 300l freezer is quite a big beast - is that figure correct, or is there a surfeit of zeros in your post? Even if the figure is correct the compressor will only be 'the next size up' so unlikely to take a huge starting load.

To answer the question Bimble do an excellent range of high(er) input voltage inverters (designed for self sufficient folks). I tested a 1200w 24v unit from them and it started a twin compressor FF with no problems at all. For some reason it wouldn't start on the power saving setting.

Could it be that you're using the power saving option - and that's where the 'buzz' comes from?

[ditchcrawler]

11 hours ago, nbfiresprite said:

My prosine 1800i uses less than that on powersave mode. The only noise you hear when inverter wakes up from powersave mode is the fan. 

1.5 watts is not bad at all

[cuthound]

15 hours ago, Mike the Boilerman said:

 

Its not a fridge, its a freezer.

 

Does anyone make a 12v freezer now? I was googling for one the other day and couldn't find one.

 

Any decent fridge technician should be able to source a suitable Danfoss 12 volt compressor and use it to replace the mains compressor in a mains freezer.

Edited September 21, 2018 by cuthound
Clarification