Waeco/mobitronic rectifier through an inverter

The fridge works if the car is running or through the rectifier plugged into mains power. It will also work using a 12V socket straight off the battery. My Engel will work in the back of the car for days, so I don't think it's wiring. I am running a healthy 105ah deep cycle battery.

Have you measured the voltage at the fridge plug while running on the various methods of powering it? a couple of fine wires into the 12v socket on the power cable will show what is actually happening with a multimeter reading the volts.


If ok on the inverter setup and direct to the battery too, you may have eliminated some of the voltage drop present in other cables which do the supply to the fridge lead. I would definitely suspect the wiring in that case. Losing too much voltage will make the Waeco stop.
If the Waeco lead has a ciggy plug, I would inspect that first, along with the wiring to the ciggy base unit, they are not the most reliable way of providing power to a fridge, even one which uses 3 or 4 amps. Most only provide a point contact for the amps to flow through.
An Engel uses less power than a Waeco, around 1/2 the amount so with the Engel the voltage drop probably isn't an issue.

Had tesame with my bushman...turned out to be where the lead plugs into the fridge, do yourself a favour and buy 2 anderson plugs, 1 for the lead and 1 for the fridge, couple up the wires, plug in and away you go

I have done all sorts since I posted this. It is all pointing towards the poly fuse which was supposed to have been replaced about 6 years ago by a Waeco repairer. I took it there twice, I'm certain he said he had replaced it with a higher amp fuse, maybe he didn't. It has never run reliably since.
I am getting readings at the fridge of 12.3V when running depending on the length of the wire I am using. Sometimes the fridge is failing at 12.3V, but other times it is working at 11.8V. I'm at the point where it's not worth spending any more money on it, just use it when I have access to 240V.
I'd like to be able to unsolder the poly fuse, bridge it and turn the fridge off when the voltage is too low myself, I would rarely ever let the battery get that low anyway.

Thanks for the advice.

I am using the standard plug. I have borrowed mates plugs, same result. I have used twin core wire with terminals direct to the fridge from the battery. That works fine, but as I add more length to the wire, the red light starts to glow a little. Add a bit more length to the wire and the fridge cuts out.

This fridge only has a switch for Low & High cut out. There is no way I know of for adjusting or setting this.

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That switch IS the setting that brianc was referring to. If set on "High" then the fridge will cut out at a higher voltage. Set it on LOW.

I just don't think there is a power reduction problem. I do understand that an inverter and the rectifier will use more power than just fridge on its own. I'm certain it is a problem with the fridge circuitry, so the rectifier would supply the correct amount of power to get around the poly fuse issue.

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If it "works OK through a 12v socket directly off the battery" then you have a volt-drop problem with your installed socket. Face up to it.

The fact that your Engel works on that socket does not determine that the voltage is sufficient for the Waeco which has selectable low-volt cutout settings. Consult your User Guide or download it.