Running 3 way fridge and freezer box from inverter?

[Bessy765]

Someone posted recently but I cant find it, about running their fridge from an inverter? So I did a little experiment, as we are going overnight Fromm Portsmouth to St Malo. Powered from 2 x 100 Transporter Lithium batteries via a 12/2000/80 Victron inverter charger. Suppling a Dometic 3 way fridge set on mains power, freezer (not compressor type) and a Dometic CX 35 Freezer box set at -10c. van is kept in my garage so no benefit from solar not on ehu. Batteries started off at 90% 20:00 heating was on low but supplied from gas so small 12 v draw. Checked this morning 09:30 batteries at 37.7%. Reason for the check was medicine that has to be kept cold and frozen fish in freezer. I am aware of putting frozen bottles ice packs etc but just wanted to see what happens?

 

[eddie]

Why not run the CX box on 12 volt? Far more Efficient

 

[Bessy765]

The cx freezer is normally run on 12 volt as turning 12 to 240 to go back to 12 is inefficient but it was left on 240 to see what happens if set this way for the amount of drain on the batteries, but you are correct to point that out.

 

[Hoovie]

The cx freezer is normally run on 12 volt as turning 12 to 240 to go back to 12 is inefficient but it was left on 240 to see what happens if set this way for the amount of drain on the batteries, but you are correct to point that out.

An absorbtion fridge on 240V (or 12V for that matter) is VERY inefficient. You will typically use around 5kWh/Day - so over twice the power from your pair of 100Ah Lithiums.
You would be best to just turn off the 3-Way and put anything that is of importance in the Dometic Compressor Coolbox. This will use approximtely 1/7th the energy. You could use 12V or 240V - the 240V on this one driven by the Victron Inverter WILL be less efficient, but not dramatically so.

 

[suavecarve]

Someone posted recently but I cant find it, about running their fridge from an inverter?

I think it might have been me last September, no baffle put into the brand new fridge so I upgraded to Lithium (which i was going to do) and had a lead that went from the lithium fed inverter to the input electric of the van.
Unfortunately I also needed to charge 2 Ebikes up each day and the weather wasnt great to recharge.

Having done experiments with length of discharge we did a complete mix of carrying a 12 volt fridge freezer in the garage which kept about 24 ice blocks frozen and would then load up the big non gas working fridge with these and swap them over, we would give it an hour or 2 boost from the inverter after charging the Ebikes (priorities). We also did a lot more EHU hook up than we have ever considered previously.

All in all, charging the 3 way off 200ah of lithium with recharge would be entirely plausible in my view, but adding bad weather and a couple of Ebike charges a day meant further battery management was required.

Its all fixed now so 2 weeks time we will have a working fridge being used properly for the first time and charging Ebikes

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[Bessy765]

Thank you for your replies, as stated in my op it was only an experiment to see if I could power the fridge for a 12 hour crossing as there will be frozen fish in the freezer box at -10 which is too cold for the medicine. But I put the freezer box on 240 to increase the load to see how much the batteries went down. So I now have no worries on a single 12 hour demand. The beauty of Lithium is the high charging to recover and no damage by running them down to 30%.

 

[denisejoe]

Did you just supply 240 volts to the fridge and ice box?

 

[Bessy765]

240 volt via the inverter to fridge set at no 2 of 5 levels and Dometic CX 35 freezer box set at -10c the heating was on. Low but using gas but a small 12 volt drain, we can all research theoretical settings and consumptions figures but can’t beat hard facts.

 

[denisejoe]

Just asking as impossible to get to my fridge 240v without pull it out

 

[suavecarve]

Just asking as impossible to get to my fridge 240v without pull it out

The reason I did what I had to do. Straight into electrics from inverter

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