wiring in a 12 v fridge

[lilianroyle]

I have a 12/240V/gas fridge, secondhand, I'm not sure of its power consumption. If I wire it to the batteries, what gauge cable should I use and what kind of fuse.
Thanks

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[stuartw]

Depends on size of fridge. A small locker type, would be around 5 amps @ 12 volts, could be as high as 10 amps. However the current on starting, will be much higher- eg 50 amps, so a cable should be quite heavy with a conductor area of at least 4 sq mm.
As regards fusing, I think a trip switch or circuit breaker, is better, which will cater for the start-up surge, and of course can be re-set. A 10 amp circuit breaker should surfice. If you want to go down the fuse route, then a 10 amp-Anti-surge or surge resisting- fuse is required.
If the fridge is bigger, and you cannot find any ratings label anywhere, then you must connect an ammeter in series and measure the running current. The start-up current can be 10 times that, but only for a short time.
Good luck

Stuart

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[Jean]

I'd suggest that it is probably a standard absorption type and hence just uses a heater (derived from mains, gas or 12V dc). On dc, the current is limited purely by the cable resistance and "starting" should not thus take any surge current as suggested by previous posting as only current difference will be slight due to heater resistance being slightly lower when heater is cold). Current likely to be around 7 amp, both for "start" and run. Hence, only real concern as far as 12v running is concerned, is can your boat electrics (batteries and alternator) handle the extra load? Probably best to interlock it with the engine electrics so that it only runs on 12v when engine is running (easily achieved via a relay energised from alternator output).

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[colvic]

That applies to compressor driven fridges whereas this is the absorbtion type as it runs off gas.

Phil

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[Heckler]

its an absorption type

and so does not have a start up as such, no compressor, but i can tell you that when i had a caravan running the same type on the car when travelling, if i forgot to switch it off 1.5 hrs later the car battery was flat, cavalier so i guess it was a 50 ampish battery.
s

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[stuartw]

Sorry-can\'t read.

Yes you're all correct, I seemingly ignored the fact that it was gas as well. Nevertheless, it still would be a good idea to measure the current, and I still would recommend a trip switch from wherever the 12V is taken from, plus the correct cable size.

Stuart

Stuart

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[SteveA]

Re: Sorry-can\'t read.

I have one of these fridges, quite a small locker type, and have measured its current draw at 12A - I won't use it unless the engine is running.

More often than not it's really used as an extra storage locker.

If I had the finances I would definitely go for a compressor unit.

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