Fridge

[CLAN1]

Hi 12v fridge on constant could it justbe the ambient temp? I know it flipping hot inside and out, just concerned its playing havoc with batteries. Any ideas cheers 

[Tracy D'arth]

Here we go, what make? How old? Compressor or absorption? Door shut and seals OK?  Is it cooling inside at all? Is the thermostat clicking when you turn it up and down? Any ice on the evaporator? How long has it been running? When did you notice it was not going on/off? Last defrosted?

[OldGoat]

IMO - the outside (and inside temperature) everywhere is very high at the moment.

As most boat fridges are stuffed under a counter with the square root of not-very-much ventilation, I suspect the poor old compressor is working very, very hard and just can't keep up with the demand - especally if it's in a small case, the interior of which is like the Matterhorn...

[Bod]

Last Defrosted?

Very good question.  It's counter intuitive, but a thick layer of ice in the ice box acts as insulator, the cold from the evaporator, cannot reach the thermostat, which gets warm, and makes the compressor run.

Along with hot weather, poor installation, the door being opened too often, poor batteries don't stand a chance.

 

Bod.

[Guest]

26 minutes ago, CLAN1 said:

Hi 12v fridge on constant could it justbe the ambient temp? I know it flipping hot inside and out, just concerned its playing havoc with batteries. Any ideas cheers 

The ambient temp will be a contributory factor but it should still be able to cope. Its probably exposing weaknesses in other areas and has been the 'tipping point'.

 

I would start with the points others have suggested. Particularly an over frosted/iced evaporator and door fit. Especially the seal condition.

 

 

[George and Dragon]

8 minutes ago, OldGoat said:

IMO - the outside (and inside temperature) everywhere is very high at the moment.

As most boat fridges are stuffed under a counter with the square root of not-very-much ventilation, I suspect the poor old compressor is working very, very hard and just can't keep up with the demand - especally if it's in a small case, the interior of which is like the Matterhorn...

That's certainly true of our fridge. I salvaged a couple of 12V computer fans with the intention of cutting a hole in the floor to draw cooler air up from the bilge and another hole below the worktop to vent hot air into the cabin. The question I don't yet have an answer to is where does more air get into the bilge?

[Tony Brooks]

13 minutes ago, George and Dragon said:

That's certainly true of our fridge. I salvaged a couple of 12V computer fans with the intention of cutting a hole in the floor to draw cooler air up from the bilge and another hole below the worktop to vent hot air into the cabin. The question I don't yet have an answer to is where does more air get into the bilge?

Probably through the gap where the floor does not sit tight against the hull sucking it from behind the hull lining. If you are concerned it won't hurt cutting a hole in the bilge inspection trap and covering with a vent.

[OldGoat]

11 minutes ago, George and Dragon said:

That's certainly true of our fridge. I salvaged a couple of 12V computer fans with the intention of cutting a hole in the floor to draw cooler air up from the bilge and another hole below the worktop to vent hot air into the cabin. The question I don't yet have an answer to is where does more air get into the bilge?

Arrr  - I designed a girt big hole under the cauliflower - not only to deal with its thermal waste but fro the fridge and cooking area where The Management creates heat to rival Vesuvius (sp:) and it keeps the bilge dry as well (no of course we have any leaks...)

[George and Dragon]

3 minutes ago, Tony Brooks said:

Probably through the gap where the floor does not sit tight against the hull sucking it from behind the hull lining. If you are concerned it won't hurt cutting a hole in the bilge inspection trap and covering with a vent.

I'll do that. Thanks!

[Alan de Enfield]

1 hour ago, CLAN1 said:

Hi 12v fridge on constant could it justbe the ambient temp? I know it flipping hot inside and out, just concerned its playing havoc with batteries. Any ideas cheers 

Has it been working properly prior to this ?

 

If your battery voltage is low the fridge will be running constantly.

If you run the engine will the fridge switch off after (say) an hour.

[Tracy D'arth]

13 minutes ago, Alan de Enfield said:

 

If your battery voltage is low the fridge will be running constantly.

 

Please explain exactly why this will occur.

[Jen-in-Wellies]

26 minutes ago, George and Dragon said:

29 minutes ago, Tony Brooks said:

Probably through the gap where the floor does not sit tight against the hull sucking it from behind the hull lining. If you are concerned it won't hurt cutting a hole in the bilge inspection trap and covering with a vent.

I'll do that. Thanks!

If there is a work top immediately above the back of the fridge, cut a hole(s) in that too. Most efficient cooling is by allowing the air to circulate up from the bilge, over the coiling coils, then away in to the cabin. 

Jen

[Tony Brooks]

Unless it is a very old swing armature compressor the compressor seems to have more in common with stepper motors so as long a sits above the automatic low voltage cut out value it will be pretty much speed independent of voltage so I don't see how low battery voltage will cause it to run all the time yet not cut out on low voltage.

[Alan de Enfield]

12 minutes ago, Tracy D'arth said:

Please explain exactly why this will occur.

I replaced the fridge in my boat with a new Waeco. It worked fine, the freezer box froze, the milk was cold. We moored up overnight and the next morning the fridge was 'awash' cardboard cartons soaked.

Started cruising and the fridge 'froze', moored up at night and by the next morning the fridge has defrosted again.

Decide to investigate - the fridge was running continuously so it should be working but it wasn't.

 

Checked the voltage at the fridge and was getting 14 volts with the engine running and 11.5 volts with the engine stopped.

 

Cut to the chase - replaced the wiring with 8mm2. Fridge worked perfectly with or without the engine running.

 

Nothing else was changed - increasing the voltage stopped continuous running.

 

Not suggesting that the OP has undersize wiring, but if his battery is low it will have the same effect / result.

Edited August 8, 2020 by Alan de Enfield

[ditchcrawler]

7 minutes ago, Alan de Enfield said:

I replaced the fridge in my boat with a new Waeco. It worked fine, the freezer box froze, the milk was cold. We moored up overnight and the next morning the fridge was 'awash' cardboard cartons soaked.

Started cruising and the fridge 'froze', moored up at night and by the next morning the fridge has defrosted again.

Decide to investigate - the fridge was running continuously so it should be working but it wasn't.

 

Checked the voltage at the fridge and was getting 14 volts with the engine running and 11.5 volts with the engine stopped.

 

Cut to the chase - replaced the wiring with 8mm2. Fridge worked perfectly with or without the engine running.

 

Nothing else was changed - increasing the voltage stopped continuous running.

 

Not suggesting that the OP has undersize wiring, but if his battery is low it will have the same effect / result.

Most would fail to start at that voltage

[Guest]

I know for certain Fridgenautica12v fridges (and freezers) just simply stop working when the batteries get too low.

 

It was one of the things that alerted us to the fact the batteries were goosed.

[Tracy D'arth]

Possibly the Danfoss 38 compressor and its associated pulse generating electronics. Low volts sounds the alarm if it is still working and shuts down the electronics.

They are not a 12v motor, they are brushless impulse driven.

[ditchcrawler]

[CLAN1]

Hi thanks for the replies. Fridge new about 18 months ago. No probs up till all this heat. Cut out vent under back of fridge years ago to help get ventilation. Back wall of fridge inside has ice on it freezer bit not overly iced, everything seems to be staying cool, fridge set at 1- 2 setting as recommended, batteries all charged up via engine & solar panel. So can only think it temp as suggested,

[Alan de Enfield]

9 minutes ago, ditchcrawler said:

Most would fail to start at that voltage

The Waco are specifically boat fridges (designed to work with up to 30 degrees of heel) and the cut-off voltage is 10.4v and cut-in voltage off 11.6v 

 

I never reached 10.4 v so it never cut-off.

 

 

 

 

 

Edited August 8, 2020 by Alan de Enfield

[Tony Brooks]

Just now, Alan de Enfield said:

The Waco are specifically boat fridges (designed to work with up to 30 degrees of heel) and the cut-off voltage is 10.4v and cut-in voltage off 11.6v 

 

 

 

 

 

 

But that is the voltage at the electronic control unit, not the battery so in your case I expect it tried to start some time in the night, suffered voltdrop on starting surge so cut out. Then defrosted. That is why thicker cables cured it, thicker cables = less voltdrop.

[George and Dragon]

23 minutes ago, Jen-in-Wellies said:

If there is a work top immediately above the back of the fridge, cut a hole(s) in that too. Most efficient cooling is by allowing the air to circulate up from the bilge, over the coiling coils, then away in to the cabin. 

Jen

It's a black granite worktop so I won't be doing that, thank you. I think i would prefer to still be alive to tell you how ineffective the hole at the side but above the top of the coil is (and drawing the heated air away with the fan).

 

ETA The resting voltage on Thursday morning was 12.4V this dropped to 10.1V when the fridge was running (yes, I know my batteries are shot).

Edited August 8, 2020 by George and Dragon

[Jen-in-Wellies]

1 minute ago, George and Dragon said:

It's a black granite worktop so I won't be doing that, thank you. I think i would prefer to still be alive to tell you how ineffective the hole at the side but above the top of the coil is (and drawing the heated air away with the fan).

Ah. Not so easy to do! ⚒️⛏️

[Alan de Enfield]

Just now, Tony Brooks said:

 

But that is the voltage at the electronic control unit, not the battery so in your case I expect it tried to start some time in the night, suffered voltdrop on starting surge so cut out. Then defrosted. That is why thicker cables cured it, thicker cables = less voltdrop.

I think I said that I tested the voltage at the fridge and it was 11.5 volts - so it never got down to 10.4 to cut-out

 

It never stopped running (I didn't stay up all night) but I was monitoring it for at least 18 hours and it never stopped running, irrespective of the temperature / thermostat position.

 

19 minutes ago, Alan de Enfield said:

Checked the voltage at the fridge and was getting 14 volts with the engine running and 11.5 volts with the engine stopped.

 

I though I did.