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Mini inverter for 240v fridge.


matty40s

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So, new Liebherr 240v fridge in, but it doesnt like our electric from the prehistoric but still working Haart interface which produces a clunky MSW.

We also had a problem in last weeks storm when the marina electric went off.

 

So, need a small inverter to power the fridge only, existing wires from the old 12v fridge are plenty thick enough.

Does anyone already use one of these and can recommend one?? What is the minimum size inverter needed.

 

It's absolutely brilliant having a fridge big enough to hold a full weeks food....havnt been to a shop since 23rd and dont need to go until the weekend..

 

20201229_171544.jpg

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Fridge start up current can be 10x the running current - is the 0.8a quoted an 'average' rate over an hour, 12 hours, 24 hours ?

 

It is not easy to quote the size inverter needed without knowing the maximum current draw.

 

As a GUESS I reckon you'd need 400 watts.

 

I tried running a fridge of a 10 amp connector and melted it (and the associated wiring) and that was a 65 watt fridge.

I measured it and whilst almost impossible to measure the peak for a split second, it was certainly over 20 amps.

 

Can you measure what current is drawn when running on mains ?

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 Not at the moment, out in the sticks, unless I run an extension cable to the West Coast Mainline gantries....

 

I was quite suprised how little information comes with the fridge, but I suppose most people would never need any more than that what is provided.

Edited by matty40s
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I think you'll struggle with a mini inverter on a fridge.  The ~200W it claims (240V 0.8A) is averaged over a set period - including when the compressor isn't running.

 

To handle compressor start up surge we usually suggest around a 1000W-1200W capability, and that's starting to get into big inverter territory.  I'm a fan of the Sunshine Solar inverters, and you might get away with the 500W or 600W one (can surge to twice rated power briefly)  but that's right on the edge of doing it.

 

https://www.sunshinesolar.co.uk/Category/PureSineWave12V

 

Using one of these in surge mode is going to be pulling between 50A and 100A down your fridge wires if you're thinking about  putting the inverter next to the fridge - just how thick and long are the existing wires?!  A dedicated mains cable for the fridge fed from an inverter near the batteries is usually the way to go with this concept.

 

What power can the Haart manage and what do you require to run off the inverter?  It might be worth upgrading your inverter for the whole boat - bung in a 2 or 3 kW one and be done with it.

 

 

 

Add: Crossposted with Alan, but we are on the same page.

 

Edited by TheBiscuits
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2 minutes ago, TheBiscuits said:

 

I think you'll struggle with a mini inverter on a fridge.  The ~200W it claims (240V 0.8A) is averaged over a set period - including when the compressor isn't running.

 

To handle compressor start up surge we usually suggest around a 1000W-1200W capability, and that's starting to get into big inverter territory.  I'm a fan of the Sunshine Solar inverters, and you might get away with the 500W or 600W one (can surge to twice rated power briefly)  but that's right on the edge of doing it.

 

https://www.sunshinesolar.co.uk/Category/PureSineWave12V

 

Using one of these in surge mode is going to be pulling between 50A and 100A down your fridge wires if you're thinking about  putting the inverter next to the fridge - just how thick and long are the existing wires?!  A dedicated mains cable for the fridge fed from an inverter near the batteries is usually the way to go with this concept.

 

What power can the Haart manage and what do you requie to run off the inverter?  It might be worth upgrading your inverter for the whole boat - bung in a 2 or 3 kW one and be done with it.

 

 

 

Add: Crossposted with Alan, but we are on the same page.

The Haart is 2.2kw, but as I said, clunky, and having the fridge on that supply still wouldnt protect against shoreline power cut, hence having a 2nd dedicated inverter.

 

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2 minutes ago, matty40s said:

Ah, https://www.sunshinesolar.co.uk/Item/C100012

I'm not going to quibble at those prices..

Looks like next job when we get back from our winter cruise is running a new 240v cable from the enjun room.

 

I've got this one:

 

https://www.sunshinesolar.co.uk/Item/VP3000

 

It's the older model, so doesn't have a little switch to toggle the N-E bond on or off which as far as I can tell is the only difference between the VP and the C-series models.

 

Did you spot the older model version of the 1000W?

 

https://www.sunshinesolar.co.uk/Item/VP1000

 

 

 

Oh and the optional remote switch is very flashenblinkenlite so you don't want it anywhere near a bed!  It pulses between one and six very bright LEDs every few seconds.

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16 minutes ago, TheBiscuits said:

 

I've got this one:

 

https://www.sunshinesolar.co.uk/Item/VP3000

 

It's the older model, so doesn't have a little switch to toggle the N-E bond on or off which as far as I can tell is the only difference between the VP and the C-series models.

 

Did you spot the older model version of the 1000W?

 

https://www.sunshinesolar.co.uk/Item/VP1000

 

 

 

Oh and the optional remote switch is very flashenblinkenlite so you don't want it anywhere near a bed!  It pulses between one and six very bright LEDs every few seconds.

That's what enjun rooms are for!!

Thanks for your help, and Alans

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I have a slightly larger - but Fridge freezer Liebherr model (waiting until the weather improve and  the virus has gone away to be installed).

I did some tests a while ago and discovered that a 1000 -1200W  PSW inverter was the minimum size that woud run it or any small household  fridge was 1200W.

It's not the running power required - it's the motor start power that's the problem.

I tested several units and found that Bimble had a low cost inverter with sufficient Oomph (a technical term) to start the Liebherr or a larger full height domestic unit without any problem, while leaving capacity for TV / recorder / w.h.y   They currently have a 1500w  PSW unit for £170 which may be a ceometitive price.

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1 hour ago, matty40s said:

Ah, https://www.sunshinesolar.co.uk/Item/C100012

I'm not going to quibble at those prices..

Looks like next job when we get back from our winter cruise is running a new 240v cable from the enjun room.

I trust the engine room is in the back cabin or in the middle of the boat. If its under deck boards don't ft the inverter there. Too much wet for long life.

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3 hours ago, Tony Brooks said:

I trust the engine room is in the back cabin or in the middle of the boat. If its under deck boards don't ft the inverter there. Too much wet for long life.

It's a proper engine room Tony, one of those where you can hang the pheasants or washing, and leave your toolboxes and muddy boots.

(Unless its Mark99s, then obviously none of the previous is allowed.)?

 

Edited by matty40s
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