Comparing power consumption of 12V compressor fridges with modern, efficient 240V fridges. Is 12V worth the price difference?

[Richard n Ann]

When I ran our mini bottle fridge off the van inverter to test it, it was sucking 6+ amps out of the leisure battery. That was on the Chinese 1000w inverter so I changed over quickly (without stopping the pot ) to the high quality Studer 275w inverter.. And it took even more at 7 amps . Our 12v compressor coolbox runs at 3 amps, or even less when it's down to temp. Must be really cheap compressor on the bottle cooler but it doesn't explain why the finest Swiss made inverter uses more power than a cheap Chinese one to run it.

 

[CamperJack]

When I ran our mini bottle fridge off the van inverter to test it, it was sucking 6+ amps out of the leisure battery. That was on the Chinese 1000w inverter so I changed over quickly (without stopping the pot ) to the high quality Studer 275w inverter.. And it took even more at 7 amps . Our 12v compressor coolbox runs at 3 amps, or even less when it's down to temp. Must be really cheap compressor on the bottle cooler but it doesn't explain why the finest Swiss made inverter uses more power than a cheap Chinese one to run it.

Is this y possible that the posh one was capable of giving more power when needed but would drop down when the bottle fridge got to the right temperature?

 

[Richard n Ann]

Is this y possible that the posh one was capable of giving more power when needed but would drop down when the bottle fridge got to the right temperature?

I suppose they just supply what the fridge wants, it's just a fixed speed compressor already down at 5°

 

[EuroTrotters]

I run a freezer 240v from a victron inverter.

Redundant Hymer TV Cupboard Now a Freezer

So, the Old CRT TV Cupboard, with turntable and up and over door. No longer required. Fridge is small, not great and the freezer even more useless. Turntable removed, door modified and hey presto, better use with refrigeration. TM So, the Old CRT TV Cupboard, with turntable and up and...

www.google.co.uk

 

[CamperJack]

I run a freezer 240v from a victron inverter.

Redundant Hymer TV Cupboard Now a Freezer

So, the Old CRT TV Cupboard, with turntable and up and over door. No longer required. Fridge is small, not great and the freezer even more useless. Turntable removed, door modified and hey presto, better use with refrigeration. TM So, the Old CRT TV Cupboard, with turntable and up and...

www.google.co.uk

Any issues keeping the batteries topped up?

^{_{Subscribers  do not see these advertisements}}

 

[EuroTrotters]

Any issues keeping the batteries topped up?

No, we have plenty of solar and batteries charge off Alternator well

 

[CamperJack]

I might buy the Victron Phoenix 12 / 1200 as recommended on here soon.

What size wire should I be using to connect it to the battery? At the moment my batteries are connected with 35mm² which is rated at 240a.

I guess that would be okay because even if I was drawing 2000w (which I should never do because the invertor isn't that big) that's only 167 amps at 12V. So it sounds like overkill, which is good. However I always like to ask you knowledgeable, helpful peeps first!

 

[CamperJack]

Just seen 12VoltPlanet recommend 25mm²- 35mm², so I should be okay with my 35mm². Shouldn't be a big run anyway. I plan on mounting it right next to the batteries.

But what size breaker should I use?

 

[Otter Spotter]

I use a 12v Thetford T1090 fridge freezer via battery which is topped up by solar and it works great even off grid, it’s a more modern design than the old weac. We don’t find it noisy and you can turn it on to silent at night when it is not noticed at all.

 

[Raul]

You likely think I'm simple by now, so thanks for your patience with me and my lack of understanding. It's great that people are so willing to help on here!

Would it be true to say that if I put the switch into eco mode and the fridge isn't running the compressor and there is nothing else plugged in to the invertor the power consumption would be only 1 or 2 watts, depending on the model?

Yes, that’s right; the inverter will pulse every 2 seconds doing a sine wave, until detects a preset load. The minimum load is specified in the manual. From memory it has to be greater than 30-40w to be seen. This is adjustable in settings on bigger inverters. On this model I think is default 30w. If the load is smaller, the inverter will not detect it. But with the fridge will work as it will surge at start.

^{_{Subscribers  do not see these advertisements}}

 

[Raul]

Just seen 12VoltPlanet recommend 25mm²- 35mm², so I should be okay with my 35mm². Shouldn't be a big run anyway. I plan on mounting it right next to the batteries.

But what size breaker should I use?

A 125a mega is perfect with the 35mm cable. You could run 150a easily, but that would encourage to overload the inverter. A 125a will not blow even at 150a spikes. And that’s 1800w, close to max surge capability.

 

[CamperJack]

Thanks again to everyone. Very helpful.

 

[twinkletoes]

I opted for the Siemens 230V fridge in my new Morelo. The main reason was to avoid the ugly grill on the side. The fridge freezer is powered from its own small inverter (Dometic) which is controlled from the compressor demand circuit. Therefore, no need for an inefficient inverter to be constantly running. The inverter switches on when the compressor is required to cool and switches back off when the fridge reaches temperature.

So far we have been very impressed. The cooling efficiency is great, getting down to temperature in around 30 minutes and to our relief we have heard absolutely no noise coming from it. We are not light sleepers, but I was conscious of the potential noise and was listening out for it, but heard nothing yet.

Not had the pleasure of using the van much yet due to COVID, but hoping that will all change soon.

Hi, can i ask what model Siemens you went for? Thanks

 

[mitzimad]

wasnt there a thread a while back where they used the fridge stat to switch the invertor on and of when needed cutting out any wastage?

 

[Richard n Ann]

wasnt there a thread a while back where they used the fridge stat to switch the invertor on and of when needed cutting out any wastage?

Yes, don't know how long a domestic stat would last switching a few amps, would be better with a big relay switching the inverter

^{_{Subscribers  do not see these advertisements}}

 

[stewartwebr]

Hi, can i ask what model Siemens you went for? Thanks

Hello,

The fridge is the standard Morelo 230Volt issue. It’s a Siemens Fridge Freezer K152L