3 way fridge

In preparation for the discontinuation (now postponed) of the 3.9 gas bottles. I thought l would run the fridge in my Trooper on 12v, so duly installed a solar panel. 

This appears to be keeping the leisure battery topped up nicely, however after chilling the fridge overnight from mains electricity it appears the fridge only works when the engine is running. Thus not using the leisure battery!

Forgive my naivety, but is this correct please???

Also where is the fuse for the fridge located. The handbook doesn't say. There is no space in the control panel on the outside of the wardrobe. Is it concealed in the fridge itself?

Any suggestions gratefully received.

Yes this is correct ,the fridge only runs on 12v while the engine is running

It will vary a bit depending on the model of fridge, but if you can find it nowhere else, you may find one of the supply fuses to the fridge behind it - an inline fuse which you can access from outside via one of the fridge vents.

As already said, it's generally not considered possible to run the fridge on 12V all the time - it takes too much power, and the 12V element doesn't typically have a thermostat, so it's likely to freeze up solid with ice in colder weather.

Thank you Chris and Roopert, l’ll bear this in mind. Good Advice.

And, from memory 10A as well and not thermostatic on 12v, so a constant 10A load on battery

IanH wrote:And, from memory 10A as well and not thermostatic on 12v, so a constant 10A load on battery

When I was running the fridge trial with using the inverter to power it my shunt was showing 10amp max and once the thermostat kicked in it was dropping to 3 amp, I would only power the fridge this way in the hight of summer when the solar was really producing excess power

I wasn't aware that the "normal" Electrolux/Thetford etc fridges had a t'stat on 12v. There is no temperature knob for 12v, just the red lit switch.
My understanding is that on 12v its just a way of maintaining the fridge temp when no 230v is poss and gas can't/shouldn't be used while travelling...

[You must be registered and logged in to see this link.]
Here's typical wiring diagram for a 4505 model. No stat I can see, there is one for the gas

Either way 10A is a big load for most vans with just one battery, and even 100w of solar.....

Its beginning to look like the solar panel really isn't going to be much use to me
Better to know though! Thanks people.

The solar panel is, IMHO, pretty close to vital!

We rarely use sites and even on sites where you pay extra for EHU we don't use it, the solar does all for our needs

Just don't expect any solution other than EHU to run the 3way fridge on electric.
Mine is on a dual battery dead simple PWM controller charging both batteries year round.
My batteries are always full which makes them happy. 
We're off on a 4 day trip this coming week, all pubstops and no EHU. I expect both batteries full by 11am the morning after a nightstop.
We will use TV, lighting, heating on gas, still needs fan, etc. We will charge 2 x phones, 2 x tablets and poss camera batts too.
We have 130w solar and both batteries. VB and LB are circa 110Ah lead acid, so nothing fancy, just simple and basic, like all things should be!!!

Hi, so now l’m thinking l either need a new fridge to run off the leisure battery ( l think Peatlander mentioned this in another post, which l cant find at present, sorry) Or an inverter.
Does anyone know please who many volts the fridge draws off the 240 mains system?

madasabrush wrote:Hi, so now l’m thinking l either need a new fridge to run off the leisure battery ( l think Peatlander mentioned this in another post, which l cant find at present, sorry) Or an inverter.
Does anyone know please who many volts the fridge draws off the 240 mains system?

I think you may mean Amps not Volts.
A fridge that will work on the leisure battery is known as a 12v compressor fridge. I’ve run these in the past without solar for 2 days on a pretty standard leisure battery, with solar it will be more than that depending on your usage.
That’s just a ball park figure, many variables involved.

Duplicate

I have no recent experience with 12 volt compressor fridges but going back 30 years we ran Engel swing motor 12 volt fridges in all our hire narrowboats and we reckoned the net current draw was about 4 amps, i.e. 50 watts, per hour. Our boats had a battery capacity of either 175 or 350 a/h at 12 volts subject to the size of the boat. Bear in mind that the boats averaged 40 hrs. running time each week. The trick was to use good heavy cabling to minimise voltage drop.

We then changed to 230 volt AC fridges run from Victron 1500 watt inverters. Domestic fridges are normally rated at about 100 watts, which at say 50% duty cycle is about 50 watts, so about the same as 12 volt consumption. We never had to increase battery or alternator capacity. You do need a minimum off 1000 watts inverter output (momentarily) to start a mains compressor fridge.

So either option is in my opinion equally viable in a motor home, and should use at least half the current of a 3 way fridge on 12 volt, provided you run the engine or use EHU some of the time or perhaps have good solar, but you will need to upgrade your charging system (certainly if you have Sargent electrics). You will probably also need to upgrade battery capacity.

I am just completing an upgrade on our Kingham’ charge / battery installation, which will be thoroughly tested next week, but one item, the installation of new heavy duty charge cables and a heavy duty split charge relay has already resulted in a major increase in the charge rate to the hab battery (with <0.1 volt drop from VB).

running on 12 volts i have had the fridge contents very frozen on long trips , no real reason you couldn't fit a thermostat on the 12 volt system , newer fridges have thermostat on all 3 power systems .

Avontourist wrote:running on 12 volts i have had the fridge contents very frozen on long trips , no real reason you couldn't fit a thermostat on the 12 volt system , newer fridges have thermostat on all 3 power systems .

Are you talking about the 12v while driving on a 3 way fridge?  I think the O/P is trying to find a fridge solution on 12v from the leisure battery.
Sorry if I’ve misunderstood your post.

I suspect the suggestion is that a 3 way on 12 volt would be more economical with a thermostat, which I suspect would be correct, but I also suspect a compressor fridge will still be more efficient and does not have the same problems with level etc. The 230 & 12 volt functions are ill thought out mods to what was designed as a gas-only fridge.

I agree that the 12v side of a 3 way often causes confusion Bargee but I disagree about the 230v. Personally I can’t fault the performance when on EHU.

Dbvwt wrote:I agree that the 12v side of a 3 way often causes confusion Bargee but I disagree about the 230v. Personally I can’t fault the performance when on EHU.

I don't disagree, but the conversation was really about electrical economy in the face of a possible problem with bulk and bottled gas supplies. I can't say that my 3 way doesn't work adequately on both 12v & 230v but I know that the 12v is current hungry and I suspect that the 230v is too, but we don't notice on EHU do we, just as we don't notice the 12v consumption when driving along 

I have noticed in the past that my average fuel consumption driving about 80 miles down to Dover is about 2 to 3 mpg better if the fridge had been precooled on mains than if it was loaded at room temperature with food from our fridge.

Dbvwt wrote:

Are you talking about the 12v while driving on a 3 way fridge?  I think the O/P is trying to find a fridge solution on 12v from the leisure battery.
Sorry if I’ve misunderstood your post.

 I was just pointing out that my fridge running on 12 volts when driving for long periods would freeze and would benefit from a thermostat,especially if running on 12 volts from solar/battery

Thanks everyone for your imputs. Still processing all the info!