Battery power consumption comparison between a household 240 volt 140 litre bar fridge, and a 12 volt 140 litre Waeco fridge.
Please note this test and
article was first done as a reply to a question on the Motorhomes Australia forum,
so if it reads a little strange, well that's part of the reason :-)
Also please note!! this test was done back in
January 2003, now because of possible improvements in fridge efficiency over the years,
this article may not be a true reflection of what you would find today if you were to do
the test using more modern fridges.
Hi Folks,
I have completed my comparison testing of two 140 Litre fridges, one a 240 volt domestic type running through an inverter, and the other a 12 volt unit.
Well the question has been asked many times, can I buy a cheaper household (domestic) fridge for my motorhome/caravan etc and run it through an inverter?
And the answer is yes you can, but you have to ask the question, will it really save you money?
Now to understand the reason that someone would want to do this is simple, a 12/240 volt fridge made for motorhomes, caravans etc, costs a great deal more than a same sized 240 volt domestic one.
The two fridges that I tested were both 140 litres, though I suspect that the domestic 240 volt one was really 131 litres, it is an ‘LG’ brand model GR-131SSF, cost $299.00, The 12 volt one is a Waeco APR –140RF, cost $1,595.00.
This comparison was purely to find out how much power each of these fridges would consume from a 12 volt battery over a 24 hour period.
Running at the same load and in the same room at the same temperature both inside the fridges and out, these tests were performed under controlled and ideal conditions, the battery voltage was a constant 13.65 volt whilst under load.
I won’t go into all the detail of the monitoring/charging/inverter/battery system at this stage, but it was state of the art and linked to a computer.
My target temperature for inside the fridges was 5 degrees Celsius (second bottom shelf), this was adjusted and set during the 24 hours run up time prior to the test period for each fridge.
The room temperature ranged from 26-29 deg throughout the test (air-conditioned).
The results:
Current consumed during the 24 hour test period.
‘LG’ 240 volt fridge………….99.6 A/H TOTAL, with 7Amp average whilst in the 'on' cycle and 42.2Amp peak on start up.
‘WAECO’ 12 volt fridge……..42.2 A/H TOTAL, with 4.5Amp average whilst in the 'on' cycle.
Now here is my angle on this.
Without going into all the pros and cons of a domestic fridge verses the purpose built fridges for motorhomes etc, like that the insolation in the domestic fridges is not as good, but hey that’s easily fixed with a tube of liquid-nails and some sheets of polystyrene foam ;-)
Lets look at the practical side of it.
If you are going to be parked up with 240 volt power connected every night (caravan park etc), then the 240 volt fridge is an option worth considering.
If however you like to bush camp a lot, and for extended times, consider this, the extra 57.4 Amps required to run the 240v fridge over and above the 12v one means one extra 100 A/H deep-cycle battery will be required (app $190.00).
Oh and them Amps have to be replace every day too, so if solar is your main battery charging source, then you need an extra 200 Watts of solar panel area (app $1925.00).
Hows the cheap fridge looking now?
Any questions folks? :-)
Val Rigoli
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