Inverter for Fridge/Coolbox?

[Blakey]

Hi guys,

I have one of these in my Beach: https://www.dometic.com/en-gb/kr/pr...d-boxes/dometic-coolfun-ck-40d-hybrid-_-64088. Well, it's in my study working as a beer-fridge, but when I'm camping... Anyway, you get the point.

I really love it and it works a treat when plugged into the 240v socket (on EHU). However the best place for it to live for us is under the Multiflex board in the back. This gives us more room in the living area, plus it happens to work that the flap on the MFB fits exactly with the opening on the fridge. Also there is a handy 12v socket in the back there.

BUT. When plugged into 12v it becomes a cooler (18 degrees below ambient) and no longer a proper fridge/freezer, and loses a lot of it's charm and potential.

So my options appear two fold:

1. Simply run an extension cable into the back off the 240v socket
2. Get an inverter for the 12v socket in the back.

If I wanted to do that latter, can someone with some electrical expertise (I have zero) please point me in the direction of one which would do the job??

Many thanks
Blakey

 

[VW Guru]

Hi @Blakey your best option would be to run an extension lead. The 12v sockets only work of a 15amp fuse using 2.5mm cable they are not man enough to run an inverter if you wanted to run an inverter you would be better connecting it straight to your second battery and still run an extension cane to where u want the fridge. Hope that helps

 

[MattBW]

Is the cooler thermostatic when on 12v or does it just stay on?

 

[Blakey]

Not sure I understand the difference? Sorry.

 

[MattBW]

Usually the 12v fridges that cool below ambient rather than to a fixed temp run all the time via a heatsink, this is why they aren't efficient.

Compressor fridges usually run only when they are above the set temp, hence very efficient. Compressors usually you hear running like your fridge at home, thermo-electric are usually a fan running constantly.

I had a look at the link and it is thermo-electric, they are generally best to run either with engine running or via the mains

On a beach which is usually a 75amp hour battery, 12v at 4amps per hour, your battery would be completely flat in less than 19 hours. In theory you would stop using it long before it was totally flat

However on an inverter 0.65amps at 240v, you would be effectively drawing 14.35amps from your 12v battery, your battery would last less than 6 hours.

I agree with the above, mains is the best most efficient way to run it and I'd personally avoid running off the leisure battery without engine running for more than half a day.

 

[Blakey]

Thanks Matt. Your timings are bourne out in practice. Off grid our fridge drains the leisure batttery in slightly less than a day. So about 19 hours makes perfect sense. I see that an inverter will let us keep it cooler - fridge temp - but drain the battery in 6 hours.

So, options become:

- Extension cable when on EHU for 240v.
- Solar panels to keep LB topped up on 12v. Only cooling not fridge levels.
- Use 12v plug when on EHU. This will run forever but only manage cooling, not fridge levels.

Thanks for the info!!

I wonder if solar panel plus inverter would let me run the fridge in 240v mode indefinitely?

 

[WelshGas]

I wonder if solar panel plus inverter would let me run the fridge in 240v mode indefinitely?

Unlikely as the sun doesn't shine for 24 hrs so your Leisure battery would drain overnight and not be fully replenished during daytime as the fridge would still be draining the battery, possibly faster than the Solar might be able to replenish.

 

[Blakey]

Okay thanks all.

 

[MattBW]

Solar would extend your time off hookup for sure, and would be more efficient on the 12v than inverter still but it wouldnt let you go indefinitely.

For that you would be best with a compressor type fridge which are far more efficient on 12v.

 

[Blakey]

Damn! I spent ages researching that Dometic fridge and am really pleased with it. Obviously didn't do quite enough research.

Any examples I can look at for comparison purposes?

 

[MattBW]

Examples of a Compressor fridges are below, but you may find the hike in price off putting to be honest. Its quite a jump over the non compressor variety.

If you tend to camp with a hookup, then I don't think you can beat the ones you have for price against level of function.

Some example compressor fridges:
Waeco CFX series or the slightly cheaper FR series.
Webasto do compressor versions as do Engel.

Most will run on mains and 12v, but more importantly will shut off the compressor when down to temperature. This results in between 0.4 and 0.9 amps per hour depending on the fridge.