Mains Fridge - How to power it?

[Jen-in-Wellies]

30 minutes ago, The Boat Studio said:

Yeah - I wasn't by any means suggesting my 50w solar panel could power the fridge! Just thought I would mention our set up. When you say 'high efficiency costs more' can you give me an example of the more efficient inverters on the market. Are Victron and Sterling any good?

Good thing to bear in mind - thank you.

A few examples of inverters well able to handle a fridge and its start up inrush.

Mastervolt (a well respected make) Mass 12/1200

Efficiency 92%

No load power consumption On mode 5W

No load power consumption, energy saving mode 0.5W

 

Victron Phoenix (also good) 12/1200

Max efficiency 92%

Zero load power 6W

Load power in search mode 2W

 

I can't find these figures for Sterling on their web site for the lower power pure sine wave inverters, only the very high power 2500W plus pure sine wave ones. This may be significant!

If you don't want to run anything else mains with the fridge off, then the idea of firing up the inverter from the fridge thermostat is a very smart one and will save a significant amount of battery charge.

 

Jen

[mrsmelly]

52 minutes ago, The Boat Studio said:

Yes - I know its not ideal. I only mentioned it as we did it on our old boat. We don't live on our boat and def don't mind going without ice cubes for the times we are on it.. Ideally we just want something to keep the milk from congealing and the cheese turning rank! Other wise we don't eat meat and most stuff we cook fresh and eat there and then. 

 

 

You don't eat meat!!! Whatever happened to your canine teeth?

[MtB]

2 hours ago, Boater Sam said:

Use a fridge with a thermostat that is simple old mechanical, no electronics.

 

Lovely idea of yours. Like all the best it's obvious, but only once someone has said it. 

 

Main thing that puzzles me is how do you identify a suitable fridge in Curry's before buying it and taking it to pieces?

Edited July 17, 2018 by Mike the Boilerman
AHHHHH the multiple post bug strikes again...

[stegra]

5 hours ago, Mike the Boilerman said:

 

Lovely idea of yours. Like all the best it's obvious, but only once someone has said it. 

 

Main thing that puzzles me is how do you identify a suitable fridge in Curry's before buying it and taking it to pieces?

For me it was simply good fortune. I hadn't considered that the lights run on 240v that for some reason is linked to the thernostat. The fridge that I linked to didn't have the interior light so no complications with the thermostat signal current going to the light. A simple get-around would be to use a universal fridge thermostat and keep the original at the highest setting. I suggest having the inverter by the batteries and running the mains cable and switch cable to the fridge. 

[Boater Sam]

On a mechanical stat you should be able to feel the click of the contacts when it is adjusted through its range. Or ask the maker?

[smileypete]

20 hours ago, The Boat Studio said:

Hi thanks for commenting so you mean wire the fridge thermostat to switch the inverter on? 

This all sounds good but I am not sure I understand fully! Can you explain a bit more how it would work? So you would use the inverter for the initial surge yes? and then only when the thermostat registers it needs more power to cool down does it turn the inverter on again?

Thanks that is handy also good to know that we should be looking for an 800 watt continuous rating.

It is ballpark though.

 

For a better idea plug it into a power monitor, set the display to amps, switch the fridge off and back on after a couple of seconds while the compressor is running. Repeat every couple of mins until the compressor stalls and you get a high current reading. Multiply by 240 to get an idea of the continuous rating the inverter needs to be.

 

Or, for your 80W fridge, just get a 1000W inverter to be on the safe side.

Edited July 18, 2018 by smileypete

[The Boat Studio]

On 17/07/2018 at 22:07, Boater Sam said:

Use a fridge with a thermostat that is simple old mechanical, no electronics.

Remove the wires from the stat and connect them together so the fridge runs all the time.

Take 2 wires from the stat to the inverter next to the fridge and connect them across the on/off switch in the inverter. Turn the inverter switch off or disconnect it.

Plug the fridge into the inverter.

Now when the fridge needs power, it will start the inverter up until it is cold enough, then it goes off, inverter uses no power unless the fridge wants it.

Thanks for this. Its a really neat little tip.

On 17/07/2018 at 22:35, Jen-in-Wellies said:

A few examples of inverters well able to handle a fridge and its start up inrush.

Mastervolt (a well respected make) Mass 12/1200

Efficiency 92%

No load power consumption On mode 5W

No load power consumption, energy saving mode 0.5W

 

Victron Phoenix (also good) 12/1200

Max efficiency 92%

Zero load power 6W

Load power in search mode 2W

 

I can't find these figures for Sterling on their web site for the lower power pure sine wave inverters, only the very high power 2500W plus pure sine wave ones. This may be significant!

If you don't want to run anything else mains with the fridge off, then the idea of firing up the inverter from the fridge thermostat is a very smart one and will save a significant amount of battery charge.

 

Jen

Thanks Jen this is really useful info.

16 hours ago, smileypete said:

It is ballpark though.

 

For a better idea plug it into a power monitor, set the display to amps, switch the fridge off and back on after a couple of seconds while the compressor is running. Repeat every couple of mins until the compressor stalls and you get a high current reading. Multiply by 240 to get an idea of the continuous rating the inverter needs to be.

 

Or, for your 80W fridge, just get a 1000W inverter to be on the safe side.

Yeah I think maybe 1000W would be the safe bet too..