Fitting a new Isotherm fridge

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Jul 24, 2009
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Summer in UK, then NZ
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We are heading off for 2 months shortly, beginning with booked ferry to Spain. Bought 12v fridge to run on battery/solar as gas is seemingly difficult now and I can't see it getting better. We have a good 180 Ah battery and 135 solar panel so hoping we shall be ok on that.

The guy that was supposed to be fitting it has disappeared - (hope he is ok?) - Hubby and I have done most of the installation and are ready to connect it. It is replacing a 3-way fridge and have identified the 12v part of the wiring. There are 2 wires into each of 2 terminals and we are guessing that we will use both of these wires in the simple black/red wiring of the new fridge. New fridge included a fuse and holder but I am not sure whether it is necessary to put it in? Any knowledgeable advice would be great please, we don't have much time and I'm a bit concerned about incorrect connections.
 

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It's fairly simple, but not quite as easy as it first appears. Normally there are two 12V supplies to a 3-way fridge. The Low Current (LC) supply powers the control board from the leisure battery. The high current (HC) supply powers the fridge 12V element from the starter battery, usually via a relay so it is only on while the engine is running.

For powering a compressor fridge, the HC supply comes from the wrong battery, and the LC supply comes from the right battery but may be a thin wire, inadequate for powering a compressor fridge. Also the LC supply may have a fuse that's too small, maybe 10A or less. You may need to run a new pair of wires from the leisure battery, with a suitable fuse near the leisure battery, 15A or 20A.

I'm guessing it's a UK motorhome, but if it's not, beware of the colours, don't assume anything. For example, black can be positive or negative.

The 135W solar panel is a bit minimal for a compressor fridge, most MHs with compressor fridges have at least 50% more than that.
 
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