Fridge Question Help please

landlubbers
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Fridge Question Help please

Postby landlubbers » Wed Oct 14, 2015 9:45 am

I have a campervan with a 12 volt 110 litre compressor fridge installed. We have recently installed 2 x 250 watt solar panels so we know we have enough power, however the fridge never seems to shut off. The ice box works and keeps things frozen, and the fridge stays at a constant temperature and stays cold but not frozen, however the fridge keeps running constantly 24 hours. We have the temperature knob set about half way around. When the fridge has been running for several hours, we can turn the temperature gauge knob inside the fridge back slightly and it will shut off. Is this normal for one of these fridges? Also, how would one go about testing the thermostat to see if that is the problem, apart from travelling 100 miles to a technician? Is there anyone out there who can shed any light? Cheers Grant

lorry26
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Re: Fridge Question Help please

Postby lorry26 » Wed Oct 14, 2015 6:11 pm

How full is the fridge and when did you do a defrost cycle like most normal 230 volt fridges by default.?
Others have found some 12 Volt compressor fridges also need a defrost cycle about every 3 months app.

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RaymonD
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Re: Fridge Question Help please

Postby RaymonD » Fri Oct 16, 2015 1:08 am

landlubbers wrote: When the fridge has been running for several hours, we can turn the temperature gauge knob inside the fridge back slightly and it will shut off.


did it restart on the new setting, if so then the original setting was max. may need regassing it temperature in fridge was not cold enough, or thermostat problem.
RaymonD

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landlubbers
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Re: Fridge Question Help please

Postby landlubbers » Mon Oct 19, 2015 6:08 pm

Thanks for your replies. We have been away freedom camping for the last 3 days and doing some testing with the fridge. Using solar power only, the fridge seems to constantly run with the thermostat about half way around. We have been turning the fridge off at night as the batteries went down to 11.9 volts. Today at home we connected our house power to the battery charger which in turn charges the batteries. The fridge is working perfectly now that the batteries have that extra oomph of power. I was talking to a fellow camper while away who suggested my problem may be remedied by adding a third battery. At present I have two brand new 110ah 12 volt batteries. So can anyone confirm if we could be on the right track by doing this? Cheers Grant

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Re: Fridge Question Help please

Postby Neddy » Mon Oct 19, 2015 6:56 pm

Grant, the root cause of your problems is the fact that the fridge is running non-stop.
Adding more solar panels or increasing your battery capacity is not the way to address this.
The fridge should have a duty cycle of maybe 35%, ie the compressor should be on about one third of the time.
The fact that it is on all the time but the fridge is not frozen means that it could well be low on refrigerant, as suggested by Ray. Get this checked.
With the fridge gassed up and cycling as it should, you will probably find your current solar and battery capacity to be quite adequate.

Neville.

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Mark
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Re: Fridge Question Help please

Postby Mark » Mon Oct 19, 2015 7:26 pm

You say that the fridge runs constantly when running off your batteries, connected to solar (ie not plugged in to a mains charger).
BUT it runs as it should, cycling on and off, when the batteries are running off the mains charger.

That seems crucial to me although I don't know the answer.

Is it possible that somehow the voltage that the charger provides is sufficient for the compressor to run as it was designed, but the lower voltage supplied by the batteries on solar, is not.

Do you know what the charge voltage that the solar controller supplies is compared to the charge voltage provided by the mains charger.
That seems to me to be the only thing that is different.
Mark

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Re: Fridge Question Help please

Postby Neddy » Mon Oct 19, 2015 7:56 pm

Most compressor fridges run just fine on surprisingly low voltages. They do incorporate a "low voltage cutout",
but this is to prevent the House battery from being completely flattened, not to protect the compressor.
The voltage sensor on my Danfoss powered fridge doesn't cut the power until the battery drops below 9.6 volts!
In Grant's case, low battery voltages are symptoms of the problem - not the cause.
They are lower than they should be, because the fridge is on all the time and not cycling as it should.
The fridge should NEVER run non-stop, regardless of the voltage.
If the battery ever did drop below 9.6 volts, the fridge would not go at all until the voltage rose above 10.9v.

I reckon Grant's fridge is low on gas.

Neville.

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Mark
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Re: Fridge Question Help please

Postby Mark » Tue Oct 20, 2015 7:06 am

Today at home we connected our house power to the battery charger which in turn charges the batteries. The fridge is working perfectly now that the batteries have that extra oomph of power.


I'm wondering why this is the case, if the problem is gas, rather than power....?
Mark


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