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reb78
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Can i use this

http://www.wickes.co.uk/Time-1-0mm2-2-Core-Round-Flexible-Cable-Orange-3182Y-25m/p/119113

To make a 5m extension to run from my 12v socket in the front of the 110 to power my new fridge in the back?

The rating for the fridge is here

post-12362-0-14495500-1464905456.jpeg

I think if i am using Fridge Freezers cable calculator correctly, i need 1mm2 cable for 75w at 12v and fusing it with a 10 amp fuse is ok? Is there any reason why i cant use the household flex i have spare (linked to above) in the garage?

Ive had a google, but still not sure how automotive cable differs to household wire other than better flex and more tolerant (of flexing) insulation

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I would say that the cable is a little light and the manufacturer agrees, but I think that they are being over conservative!

In this case the cable is specified as 1mm2 CSA. Copper has a resistivity of 0.0172 Ohm∙mm²/m. For a total (feed and return) run of 10m, that equates to 0.172 Ohm. Add 0.1 Ohm at least for connector.

Simplistically, 75W equates to a nominal 6.25A or a nominal voltage drop of 1.14V, which would drop the power to the fridge by ~20% with consequent reduction in cooling effect. Not quite that bad because reduced volts also means reduced current. Assuming linear load characteristics , voltage drop would actually be nearer 1V, but still 18% reduction in cooling power. Go to 2mm2 and you’re down to just over .5v drop and 9% loss of cooling power.

The manufacturers manual recommends >4mm2 which is too big for a cigar lighter connector. Incidentally it also confirms the interpretation of butane/propane pressures.

Manual available here.

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Thanks for this. Ideally i would like to mount a battery further back in the car and so could avoid long runs of cable to it from this and any other accessories in the back. I'll get some better cable for now as you suggest and take it from there.

Im still testing the fridge. I'm not convinced i havent bought a pup as its not cooling as much as i would have thought. Seller put the ususal caveats about it being stord and sold untested, so i took a chance and dont think i have any comeback. Its been on overnight on 240v and the end of the large pipe inside is frosty, but the unit isnt that cold inside overall.

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I have run 6mm auto cable which is 4.59SQM to the rear of my disco from the auxiliary battery to power my fridge and lights, i wouldnt use anything smaller especially for a 3 way that will draw a lot of current.

Turn the fridge upside down for an hour or 2 then back upright and then turn it on, they have a habit of settling when left for long periods.

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