Fridge 12volt problem

Jul 31, 2010
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The 12volt supply to the fridge in my Swift Challenger Utopia 530

stays on when the car engine is switched off. I don't know if it has always done this and I have not noticed it before, or if it has just started doing it. The Car is 10 months old and the van is just coming up to 5years old. It is still connnected when the ignition key is in my pocket.Is this normal or should a relay disconnect the cicuit when the ignition is switched off.

Thanks in advance for any suggestions.

Steve W
 
Mar 14, 2005
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It should switch off as the voltage from the alternator reduces and the voltage sensing relay on the car opens.

When I fitted one to my car a few years ago the fridge was still on 30 min after the ignition was switched off so I took the voltage sensing relay back and replaced it with a mechanical older type.

I have seen a lot of the voltage sensing type play up !!

But the good news is that the later ones I believe are adjustable so have a look to see if there is a screw that you can adjust.

If not you will need a new relay.
 
Mar 14, 2005
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Steve, John has given you good info but can you also confirm that during the time the fridge is still connected, ( I assume you know because the red 12v lamp is on) that you cannot use the van 12v lamps or water pump etc?

As John said the modern (lazy) way of doing things is to run a single 12v supply (plus -ve) for the permanent feed from the car battery . This also goes to operate a voltage sensing relay which when operated feeds 12v to the fridge circuit. The relay operates by sensing the rise in voltage when the engine is running. They are well known for 'hanging on' when the engine is switched off and also for a delay in operating. Another effect is that they 'chatter', that is they activate and when the fridge load is applied there is a slight drop in voltage which drops them out. The voltage then rises again and the cycle continues. As John rightly said hopefully there is an adjuster screw on the relay which will enable you to set it for optimum.
 
Mar 14, 2005
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ref.fridge on 12v. mine is connected directly to the alternator, so only works when the engine is running. is this ok or should i now start worrying about it?

Emmerson
 
Mar 14, 2005
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emmerson, There is no need to worry. This is the way things were done until the voltage sensing relay became popular in late 90's. It is the system John was advocating if Steve couldn't get his volt sensing relay to work reliably.
 
Mar 14, 2005
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emmerson, There is no need to worry. This is the way things were done until the voltage sensing relay became popular in late 90's. It is the system John was advocating if Steve couldn't get his volt sensing relay to work reliably.
Emmerson, don't want to appear pedantic but your fridge is fed from a battery connection via a relay. It is the relay operating coil that is fed from the alternator. Ray
 
Mar 14, 2005
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Emmerson, don't want to appear pedantic but your fridge is fed from a battery connection via a relay. It is the relay operating coil that is fed from the alternator. Ray
Thanks Ray.Just as long as I can keep the booze cool!
 
Mar 14, 2005
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Ray,thanks for the support.

The delay you spoke of was apparent when last week we fitted warning lights (12V & 230V) to my friends van on site!

He started the engine and walked back to the caravan before the habitation relay kicked in and the interior light went out/fridge warning light came on.

Holding a meter on the fridge 12V it read 14V with the engine running but this dropped to 11V when the fridge was switched on.

This could account for the chattering you spoke of I suppose.
 
Mar 14, 2005
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John, the main problem is the size of the wires being used. It is a fairly long way from the car battery to the fridge. If the the wires are only 1.5mm then a volts drop of 2 volts is easily possible. There is also the chance of some volts drop through the 12S pins. The volts drop is also the reason that people complain that the fridge doesn't keep the fridge cold whilst on the move, it really needs a good 12v or so to keep the element hot.

The best thing to do is wire everything in 2.5mm wires and double up through the 12S using unused wires.

regards Ray
 
Mar 14, 2005
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Ray,couldn't agree more about wiring size etc.

My own wiring is much thicker that the 2.5 mm and when Towsure fitted my towbar they tested my wiring and it was greeted with approval.It lit all their bank of fog lamps --no problem

Voltage drop was also a problem with the Swift feed to the TV socket which had 10+ metres of cabling that did one lap of the van before arriving back at the Tv point which was 2 m from the battery.

A shorter thicker run using the original as trigger for a relay(old type) vastly improved TV and Omnimax performance while retaining habitation relay function.
 
Mar 14, 2005
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Ray,couldn't agree more about wiring size etc.

My own wiring is much thicker that the 2.5 mm and when Towsure fitted my towbar they tested my wiring and it was greeted with approval.It lit all their bank of fog lamps --no problem

Voltage drop was also a problem with the Swift feed to the TV socket which had 10+ metres of cabling that did one lap of the van before arriving back at the Tv point which was 2 m from the battery.

A shorter thicker run using the original as trigger for a relay(old type) vastly improved TV and Omnimax performance while retaining habitation relay function.
Also double up using spare pins in 12S!
 
Apr 13, 2005
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Hi as your all probably aware i recently changed my galaxy for an alhambra and had the dealer fit my towbar for me, when i collected the car i was concerned about the fact that they had wired the fridge and charge supply to the rear power socket of the car. The dealer assured me that this was ok and was how they wired all towbars, now my alhambra has its own fridge in the back which runs at 5 amps that leaves only 5 amps for the van to use for its fridge and charge circuit and on our recent trip to the isle of wight we found that the vans fridge had completely defrosted, I checked that we had 12 volt on the 12s and that all fuses where ok and assumed that the fridge must be faulty so i booked the van in to have it repaired as its only 3 month old, it goes in next week. I now find myself wondering whether the fault could be the supply from the car after all as the socket is supplied by a 1.5 mm wire, i think having read the above i will re- wire the 12 s myself as i'm not too happy with all that power going through the aux socket.
 
Mar 14, 2005
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Icemaker, You need to check the voltage at the fridge as John did with his friends. You are aiming at 12v with the fridge switched on. I am unsure how you have worked out the amperage available to you for both of your fridges. The van fridge will try to draw about 7A and your car icebox 5A so ideally the circuit and wiring should be able to carry 15A minimum. There is a good chance that with your current set up that the car icebox will also not work to full capacity. It would be interesting to measure the voltage at the car socket when the van is connected and both fridges switched on - does it stay above 12V?

Do not always trust tow bar fitting centres. When I had one fitted they did the same as they did on yours. They also used it as the source of the permanent feed, which of course it wasn't as on my car the socket is not live until ignition is switched on.
 
Mar 14, 2005
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Icemaker, You need to check the voltage at the fridge as John did with his friends. You are aiming at 12v with the fridge switched on. I am unsure how you have worked out the amperage available to you for both of your fridges. The van fridge will try to draw about 7A and your car icebox 5A so ideally the circuit and wiring should be able to carry 15A minimum. There is a good chance that with your current set up that the car icebox will also not work to full capacity. It would be interesting to measure the voltage at the car socket when the van is connected and both fridges switched on - does it stay above 12V?

Do not always trust tow bar fitting centres. When I had one fitted they did the same as they did on yours. They also used it as the source of the permanent feed, which of course it wasn't as on my car the socket is not live until ignition is switched on.
Icemaker, a quick way to check the fridge is to get a charged battery (85AH or more). Using a spare 12S socket connect 12v+ to pin 6 (via a 10A fuse) and -ve to pin 7. Plug the van in and check the fridge gets cold - the fridge will draw about 7A so it has time to get cold, perhaps 3 hours, before the battery is flat. Ray
 
Apr 13, 2005
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Ray, the cars fridge has a plate on it that rates it at 5 amps, what i meant by having only 5 amps for the van was due to the socket being fused at 10 amp. of my memory from school to work out amperage you divide the wattage by the voltage to get the amperage. I will check the voltage tommorow when home from work but i'm fairly confident that it will be well below 12 volt. shame i did not think of this earlier.
 
Mar 14, 2005
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You may find that the voltage at the socket is above 12v even with both fridges on. Ideally you would hope that the van socket is 14v or so (alternator output)and a volts drop of less than 2v to the van fridge with both fridges on. Good luck with your tests it will be interesting to hear your results. Fridge problems on 12v come up constantly on the forum so more kmowledge the better.I think you need to rewire the circuits to be seperate as you are thinking of doing. If the circuit is indeed fused at 10A then I think you are heading for problems if you do get any volts drop sorted out. You will be drawing 12A before you even start to charge the battery. Ray
 
Mar 14, 2005
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Electrolux/Dometic say that a 16 amp fuse should be used in the 12 V supply and I would have thought that modern fridges would use more like 12 amps.

We made a mod to my friends Subaru en route to Spain,when the relay packed up, by wiring to the boot socket but nothing else was plugged into itand it was on a 15amp fuse.

You need to run heavy cable from a battery + terminal by crimping a ring /fork terminal and putting it under a second nut on the battery clamp.As close as you can get to the battery put a fuse in the line and then the relay can go somewhere in the line to the 12 S socket(usually the boot where it can be got at )

Its better to avoid disconnecting because of radio memories etc.

So called fitters are often in a hurry and use Scotchlocks which often give trouble.

When double relays were fitted (one for fridge /one for charging) I went to an auto electrical co in Lancashire for a double relay.They said that it wasn't needed and just put the two output leads together in one crimp on terminal.When I pointed out that when I stopped on a layby etc there would be a circuit from the caravan battery to the fridge via the terminal which would flatten the battery they said well you just unplug from the car then !!!!

I never went there for service again.
 
Mar 14, 2005
4,638
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Electrolux/Dometic say that a 16 amp fuse should be used in the 12 V supply and I would have thought that modern fridges would use more like 12 amps.

We made a mod to my friends Subaru en route to Spain,when the relay packed up, by wiring to the boot socket but nothing else was plugged into itand it was on a 15amp fuse.

You need to run heavy cable from a battery + terminal by crimping a ring /fork terminal and putting it under a second nut on the battery clamp.As close as you can get to the battery put a fuse in the line and then the relay can go somewhere in the line to the 12 S socket(usually the boot where it can be got at )

Its better to avoid disconnecting because of radio memories etc.

So called fitters are often in a hurry and use Scotchlocks which often give trouble.

When double relays were fitted (one for fridge /one for charging) I went to an auto electrical co in Lancashire for a double relay.They said that it wasn't needed and just put the two output leads together in one crimp on terminal.When I pointed out that when I stopped on a layby etc there would be a circuit from the caravan battery to the fridge via the terminal which would flatten the battery they said well you just unplug from the car then !!!!

I never went there for service again.
Ray I was typing this before you last post appeared!
 

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