# Running a fridge off an inverter



## hassnz1 (Jan 10, 2018)

Hi All,
Thinking of replaceing our old fridge, and would like to get one that we could run off an inverter.
Any surgestions on what size house battery and how much solar watts we should have. 
Not even sure this can be done as we are new to motor homing.
Cheers
Allan


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## Pudsey_Bear (Sep 25, 2008)

Hi Allan and welcome to MHF, it is possible of course, Waeco do several 12v fridges which would be a better option than an inverter, they do tend to be a bit smaller, almost like a domestic drinks fridge in some cases, it is a step backwards if replacing the one already fitted, 3 way is the better option, not a lot of sun in winter so reliant on site EHU.

Why do you want to go that way out of interest?

http://www.waecofridges.co.uk/


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## listerdiesel (Aug 3, 2012)

Quite honestly, unless you're going to put some serious sized batteries in, you'd be better off running a gas fridge.

Most 12V and 240V fridge elements are 100W, gas is equivalent to 160W.

A 100W 240V element would need 2.4amps as a straight conversion, add your inverter inefficiency of about 85% gets you about 120W which is going to be just over 9A at the battery, assuming 13V terminal voltage. 

At 13V input the 100W element will take 7.7A, a bit less as you haven't got the inverter losses.

Either of those will deplete your battery fairly quickly, 110AH is a 20 hour rate, which falls fairly rapidly as the discharge current rises, you can expect under 95AH at 7A discharge.

As far as solar goes, you'd need 250W minimum to support that kind of load, allowing for losses and average sunshine in the summer, forget solar in the winter.

Peter


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## Pudsey_Bear (Sep 25, 2008)

Well you could put it that way I suppose


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## p-c (Oct 27, 2007)

Hi Allan and welcome

As Peter says!

We tend to refer to the battery in the motorhome as the habitation battery or leisure battery.

As Kev asks, why?

Regards

p-c


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## nicholsong (May 26, 2009)

Hazznz 1

As others have asked Why?

Kev has told you it is possible and Peter has done the calculations.

However, 99.9% 0f MHs and caravans have 3-way fridges which are powered by

1. 12v for the engine alternator when driving

and when stationary from

2. 230v from campsite hook up to their electrics
or
3. Gas

If you have a 230v fridge you lose the ability to use gas, which saves on precious electrical power when away from campsites, and as Peter pointed out gas is more efficient.

Your precious electrical generation will be needed for all the other equipment run off the batteries and inverters are inefficient and a wasrte of that electricity capacity for high demand units like a fridge when there are alternatives.

These points alone are the justification for the majority of MHs to have 3-way fridges.

You would need to have very special reasons to decide otherwise.

Geoff


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## 747 (Oct 2, 2009)

If you don't want a 3 way fridge with gas, then get a 12 volt Compressor Fridge like these.

http://www.jacksons-camping.co.uk/cool/fridges_coolmatic_absorbtion.htm

Plenty of selfbuilders prefer these to 3 way fridges ..... and they are cheaper.


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## hassnz1 (Jan 10, 2018)

Only because 240v inverter fridges here are the cheapest option.
Thanks for your replies. 
Cheers
Allan


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## Pudsey_Bear (Sep 25, 2008)

Where be here Allan? More info equals more focused help.

You have to offset the lower fridge cost against the higher cost of the battery bank, solar inverter and controller.


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