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Engel 12V Fridge

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Can anyone confirm that I'm thinking along the 'right lines' here.

Having very recently bought a 3 year old Viking 24, which is fitted with an Engel 12V fridge.

When we took the boat out for the first time last weekend, running for 3 or 4 hours, the fridge got nice and cold.

On thursday, I went up to the boat to spend a couple of days, doing some work on it, and staying over night. The boat was 'hooked up' to 230V shore power. In order to have fridge on, without draining the battery, I put connected a battery charger to the battery, and let it run in 'float charge' mode.

However, the fridge did not get cold.

I assumed that, like my caravan fridge (a Dometic 12V, Gas, Mains), while towing, 12V is only connected to the fridge when the engine is running (a voltage sensing relay in the car takes care of this). As the Dometic fridge will draw up to 10 Amps from the car supply, this prevents the flattening the car battery, when the engine is off, but the fridge still connected to the car.

I believe the Engel fridge only draws something like 3.5 Amps, but obviously enough to drain a battery over several hours.

If it is the case, that the boat fridge is only activated via the ignition switch circuit, then I will need the wire in a bypass switch, so that I can run the fridge on the 12V system, when on the marina mooring with the ignition circuit switched off. The 230V 'shore supply' powering a battery charger in 'float mode', maintaining the battery power.

What is confusing, is that with the shore power connected, I can here what sounds like a fridge compressor running all the time. The sound coming from the vent below the fridge. Switching the fridge to off, via it's internal switch, has no effect on this compressor type noise. Switching off the whole of the 12V at the isolator, also has no effect.

Disconnect the 230V shore power supply, and the noise stops. :?

Any thoughts on this ?


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Dave, if I'm right you can't run it through a charger, it has to be 12v or 230v and to run it on 230v you have to unplug the 12v lead, I have an information sticker on the inside of the fridge door I'll try and get a piccie of it and post it here tomorrow evening, I think on the new models it auto switch over from 12v to 230v but as mine is about six years old I pressume it's the same set up as yours,,


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:? Oooh! I forgot I've got a question as well, my latest boat has an Engel fridge on as well,, now I know they don't use a lot of juice, and the label inside the door recommends setting the thermo at No3, what I need to know is, when you moor up do you switch the fridge off or leave it running all night, I have a 110amp domestic battery on a seperate circuit, but with the little telly, lights, waterpumps etc I can't see the battery lasting very long with the fridge left on, so how do you use your fridge??
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I don't know why everyone seems to have such problems with fridges.

I've been through the "problems with fridges" stage and it's always been due to a duff battery or heavily corroded wires. A decent and properly working fridge coupled to a decent and properly working battery has never been a problem. Although we're fairly restless boaters we have been known to moor up of an evening and not leave until the following afternoon, sometimes late afternoon. The fridge is still working at that point having been switched on all night and all the following day and we only had 1 x 110Ah battery. In fact when we go out boating the fridge is on from the time we arrive at the boat to the time we turn everything off and leave, be it 1 hour or 1 week.

Dave, have you tried putting a multi-meter on any circuit when the fridge is not functioning? It will have a low voltage shut off so if the voltage is below that point it will not start. Also what can happen is that badly corroded points along the wire can reduce the amount of current able to flow through the wire. The fridge will normally need a certain amount of amps to kick the motor in, though that immediately drops to a much lower level to run the motor for a few minutes. As the wire degrades resistance rises reducing the amount of current which can be drawn through the wire. Also, the lower the voltage on the circuit (as the battery discharges) the higher the number of amps required to start the motor which can mean that when the engine is running and the system is being charged at 14V the fridge can start but when the voltage drops to say 11V a higher current is needed to start the motor and the poor quality wiring can not deliver it. What tends to happen then is that the fridge tries to kick the motor into life, the voltage drops significantly on the wire as the fridge tries to pull the current, and the motor just makes a clunking noise and then the compressor hums and bubbles for a few moments but no actual cooling takes place.

The one thing I would say is that if you have a mains charger for your batteries the fridge should run because it should push the system voltage up to around 13.5-14V in much the same way that the alternator would if the engine was running. My Engel fridge also has a 230V override which means that if 230V AC power suddenly becomes available it runs off that rather than off the DC system.

Check your battery, check your wiring, check your mains charger setup - bottom line is what you describe should not be happening.

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Thanks for your respsonse guys.

Yesterday, we were out cruising for some 4 or five hours, and the fridge functioned very well.

The wiring on the boat is in good order (it is only 3 years old), and all electrical connections are clean and tight.

The boat has 2 x 85AH batteries, which can be selected as Bat 1, Bat 2, or Both, via the isolator switch.

Both batteries show 12V in an unloaded state. This of course rises to around 13.8V with the engine running and charging.

When I was connected to 230V 'shore power', and with a battery charger connected to the batteries, the voltage was at the battery was around 13.8V, but the fridge didn't get cold.

Hence my belief, that for some reason, the fridge is only supplied with 12V, when the ignition circuit is switched on. As with my car, certain functions (electric sunroof & windows, wipers etc), will only operate with the ignition switched on.

I can only assume, that the fridge was deliberatley wired this way, to remove the possiblity of the fridge draining battery. Albeit, with the facility to be able to select either battery, Bat 1 could always be kept for engine starting, and when moored, switch to battery 2 to run the the 12V appliances and lighting. That way, there would always be a charged battery for starting.

I need to trace the fridge wiring, and remove it from the ignition circuit, and connect it to the non-ignition activated 12V supply wiring.


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Hi Dave, if you don’t have a permanent hard wired shore power charger some domestic appliances are wired by the manufacturer to only draw with the engine actually running (Voltage sensed from alternator version) and thus charging the batteries or alternatively only with the key in the “run†position ( simpler version). There is nothing unusual about this on modern boats at all, it is however a right Royal PITA if you’re not expecting it. A simple override is an easy job as at only three years old the boat will have been furnished with full manuals and wiring diagrams, a legal requirement for CE marking.

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It is a "hard wired" shore power installation, via a statutory RCB switch unit on the boat, and two 13 Amp double outlet sockets in the cabin.

However, it seems that Viking didn't, or doesn't, fit a mains to 12V charger (unlike my touring caravan, which has a ZIG power unit).

Strange this, because this particular boat, was Viking's 2006 London Boat Show exhibit, and as such was fitted with many extras (including posh carpet in the cabin :lol: ).

As you say, it won't be a problem to by-pass the ignition circuit, and feed the fridge directly from the 12V system, now that I'm aware of what's actually going on with the fridge.

I do indeed have all the manuals, but the wiring diagram for the boat's electrics is very crude, to say the least, and as such, about as much use as a 'chocolate fireguard'.

Thanks for your interest.


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  • 2 weeks later...

Ok, I've sorted the fridge problem :grin:

The problem was 'man made', either by the previous owner of the boat, or by Viking when they initially built and fitted out the boat.

I removed the fridge from the cabinet into which it was fitted, and found that the fan I could hear running, was not part of the fridge, but attached to a mains to 24V DC PSU. The PSU also had a 12V DC input. The unit was designed to auto switch between 24V DC out, when mains power was applied, and then to the boat's 12V battery system when the mains supply was removed. The fan was to cool the Heat Sink of the regulator.

The unit functioned exactly as it was designed to do, except the fridge is designed work on a nominal 12V DC supply. NOT 24V :norty:

When the fridge was supplied with 12V DC, and no 'shore power' (230V AC) connected to the boat, the fridge functioned perfectly. As soon as 'shore power' was connected 24V DC was applied to the 12V fridge, and it obviously didn't like it, so refused to run.

I have brought the PSU home with to see if I can change the regulator to give a 12V (13.8V) output. I may have to increase the efficiency of the 'heat sink', to dissipate the extra heat from 'dumping' 12V of the 24V.

I've now installed a regulated battery charger on the boat, that has both a 100% charge function, and 'permanent float'.

When 'hooked up' to shore power, both batteries now receive a 'float' charge.

Sorted!! :dance


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  • 2 weeks later...

I have brought the PSU home with to see if I can change the regulator to give a 12V (13.8V) output. I may have to increase the efficiency of the 'heat sink', to dissipate the extra heat from 'dumping' 12V of the 24V


I didn't have to change the regulator ( a pair of them in fact), as they were LM338, which are adjustable output voltage regulators, capable of handling up to a 5 Amp load current. With the pair, the PSU has a 10 Amp load current capability, so plenty 'in-hand' for the 3.5 Amps drawn by the fridge.

Having calculated the value of the new output voltage setting resistor combination, and then replacing the existing ones, with the new values, I now get a nice 13.5V :).

I also had to change the PCB mounted changeover relay, from the existing 24V unit, to a 12V unit. Costing the princely sum of 60P :)

Bolted on beefier heatsink, and 'bingo', one 24V regulated PSU, now running as a 13.5V PSU.

Will put a 'load' on it tomorrow, and let it run for a few hours, to 'soak test' it, and if all is ok, then I reinstall it in the boat.


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