12v fridges

[MtB]

1 hour ago, curlass24 said:

so went for the waeco crx 80.

 

have fitted an started up fine, the freezer doesn't appear to be cold enough though, does anyone know why this is? Also what temperature setting do people run these on? we have it on 3 and have two solar panels so hoping that will be enough.

 

Thanks,

 

 

Did you check the cross sectional area of the cables supplying the fridge as advised by several posters earlier in this thread? What cross sectional area are yours? (It's usually written on the cable insulation in tiny writing, ever metre or so.)

 

Freezer not getting cold enough is a typical symptom of the cables being too thin. Wiring up a 12v fridge correctly is not a trivial exercise.  Your comment earlier about having twin wires feeding the fridge connection point suggests to me one pair of (probably very thin) wires to the fridge location, and the second pair of wires then go off to feed a further 12v socket outlet elsewhere in the boat. Quite probably totally inadequate for running a fridge and the cause of this problem. 

 

 

[Dr Bob]

On 27/02/2019 at 17:35, mrsmelly said:

You could have bought a first rate mains fridge for 150 quid, lots of sizes and choices and run it through an inverter. Running costs re similar or just a tad more than 12 volt. I sold both my 12 volt fridge and 12 volt freezer and went all mains again on this boat as I have with others and I never regret it. You can buy a good quality inverter with the change from the rip off cost of 12 volt units. I have checked mu useage against the 12volt units that were fitted and on this boat its near as damn it the same as when I had 12 volt.

I fully agree with Smelly. 240V doesnt suffer the wiring issues and our power consumption is less than 30Ahr per day. Much bigger choice of fridges and  soooooo much cheaper. Not much use to the OP now but relevant to anyone about to invest in a new fridge.

[Alan de Enfield]

25 minutes ago, Mike the Boilerman said:

 

Did you check the cross sectional area of the cables supplying the fridge as advised by several posters earlier in this thread? What cross sectional area are yours? (It's usually written on the cable insulation in tiny writing, ever metre or so.)

 

Freezer not getting cold enough is a typical symptom of the cables being too thin. Wiring up a 12v fridge correctly is not a trivial exercise.  Your comment earlier about having twin wires feeding the fridge connection point suggests to me one pair of (probably very thin) wires to the fridge location, and the second pair of wires then go off to feed a further 12v socket outlet elsewhere in the boat. Quite probably totally inadequate for running a fridge and the cause of this problem. 

 

 

This was EXACTLY the problem we had when we replaced the old fridge with the new Waeco. (See Post #2)

Freezer froze with the engine running (14.4 volts), but defrosted when the engine stopped.

Checked the volt drop and only just over 11.5 volts was arriving at the fridge with the engine off.

Fridge was running virtually continuously and achieving nothing.

 

I must admit I made the fatal error of assuming the he had checked or replaced the wiring as requested earlier in the thread.

 

ASSUME = Makes an ASS out of U and ME

Edited April 8, 2019 by Alan de Enfield

[MtB]

12 minutes ago, Dr Bob said:

I fully agree with Smelly. 240V doesnt suffer the wiring issues and our power consumption is less than 30Ahr per day. Much bigger choice of fridges and  soooooo much cheaper. Not much use to the OP now but relevant to anyone about to invest in a new fridge.

 

And in the eight months of the year when God turns the solar ON, the inverter overhead is pretty much irrelevant. 

 

That still leaves the four dark months to struggle through, for those without a Whispergen.

 

 

[Dr Bob]

3 hours ago, Mike the Boilerman said:

 

 

That still leaves the four dark months to struggle through, for those without a Whispergen.

 

 

Ah, but that's when you get some lithium's.

[Kathymel]

On 08/04/2019 at 09:59, Mike the Boilerman said:

 

Did you check the cross sectional area of the cables supplying the fridge as advised by several posters earlier in this thread? What cross sectional area are yours? (It's usually written on the cable insulation in tiny writing, ever metre or so.)

 

Freezer not getting cold enough is a typical symptom of the cables being too thin. Wiring up a 12v fridge correctly is not a trivial exercise.  Your comment earlier about having twin wires feeding the fridge connection point suggests to me one pair of (probably very thin) wires to the fridge location, and the second pair of wires then go off to feed a further 12v socket outlet elsewhere in the boat. Quite probably totally inadequate for running a fridge and the cause of this problem. 

 

 

What should the minimum cross-section be? 

[Alan de Enfield]

3 minutes ago, Kathymel said:

What should the minimum cross-section be? 

It depends on far from the battery the fridge is.

 

Let us know and we'll give you the answer.

[Kathymel]

What do people think of this idea?

 

http://www.aselfsufficientlife.com/chest-freezer-to-fridge-conversion-the-most-energy-efficient-fridge-ever.html

 

I originally dismissed it as I didn’t think you could get 12v chest freezers, but, having read the positive comments on here about running a 230v fridge, maybe it has legs?

 

The comments on the article identify an issue with condensation, but it seems a wipe out once a week keeps this in check. Also, it being top-opening would make counter space less useful, but that’s more than compensated for by the savings imo. 

 

I just wondered if anyone on here could come up with other possible negative points. 

[Kathymel]

17 minutes ago, Alan de Enfield said:

It depends on far from the battery the fridge is.

 

Let us know and we'll give you the answer.

I think it could be around 14m of cable. Hard to tell exactly due to it dog-legging to the switchboard and back. 

[Alan de Enfield]

7 minutes ago, Kathymel said:

I think it could be around 14m of cable. Hard to tell exactly due to it dog-legging to the switchboard and back. 

Do you mean 14 metres from battery to fridge (ie 28 metres there & back?)

 

If so you are looking at least 30mm squared cable. That is a heck of a long run and 50mm squared would be better.

[Kathymel]

Thanks Alan.

 

As the crow flies, it’s about 9m, but there’s a fair bit of up and down and side to sideness. 

 

Ive no idea what 50mm looks like, but the stuff I’ve got looks no bigger than ordinary domestic cable. 

[Alan de Enfield]

3 minutes ago, Kathymel said:

Thanks Alan.

 

As the crow flies, it’s about 9m, but there’s a fair bit of up and down and side to sideness. 

 

Ive no idea what 50mm looks like, but the stuff I’ve got looks no bigger than ordinary domestic cable. 

You may manage with 20-25mm squared

 

You are looking at cable about 10mm - 12mm diameter over the insulation for EACH core.

Edited April 27, 2019 by Alan de Enfield

[Kathymel]

46 minutes ago, Alan de Enfield said:

You may manage with 20-25mm squared

 

You are looking at cable about 10mm - 12mm diameter over the insulation for EACH core.

That’s a slight relief. Looking at 50mm cable on eBay, I was seeing prices around £10/m. 

 

Even so, that’s huge cable. 

Edited April 27, 2019 by Kathymel

[WotEver]

1 hour ago, Alan de Enfield said:

You may manage with 20-25mm squared

 

You are looking at cable about 10mm - 12mm diameter over the insulation for EACH core.

Nope, you have that wrong, Alan. Shoreline recommend 1mm² per metre run one way. So a 14m run should be 15mm² as a minimum. 

[Alan de Enfield]

4 minutes ago, WotEver said:

Nope, you have that wrong, Alan. Shoreline recommend 1mm² per metre run one way. So a 14m run should be 15mm² as a minimum. 

My Waeco installation manual has a graph showing the 'one-way' length against CSA 

14mts is just off the scale, but extrapolating it looks like about 19- 20mm²

 

12 metres run is shown as 16mm²

A 10mts run is shown as 14mm²

 

I know we have had these discussions previously but, If I install it to the manual then if it doesn't work the problem is the fridge.

[WotEver]

See page 4 on this pdf:

http://www.shoreline-marine.co.uk/admin/document_library/RRInstructions_BD35ONLY.v16_011211.pdf

 

Perhaps Waeco use a different compressor?

[Alan de Enfield]

[Dr Bob]

9 hours ago, Alan de Enfield said:

So for our boat where I would need approx 12m of cable to reach the fridge, I would need to spend £100 on cable. You could almost buy a proper fridge (240v) for that!  

[Alan de Enfield]

9 minutes ago, Dr Bob said:

So for our boat where I would need approx 12m of cable to reach the fridge, I would need to spend £100 on cable. You could almost buy a proper fridge (240v) for that!  

Or, you could by a small house for the price of a boat;

[dmr]

12volt fridges are good things, but certainly not cheap, cabling included . I think they all use the same Danfoss compressor though there might be a Chinese version.

Shoreline and Waeco are the big names but these people look good:

 

  https://www.inlanderlowvoltage.com/             

 

I will certainly consider them when its time to replace the our Shoreline. I think (not sure) that they will also do custom conversions on a mains fridge of your choice.

 

There are two issues with 12 volt fridges on boats:

 

All the cost is in the the compressor and conversion, the base "donor" fridge used by Shoreline is usually a fairly basic model, so its sad to be paying so much for a cheap fridge.

They only use a single thermostat (in the fridge) and boats can go below the minimum operating temperature, especially if left unattended in winter. This means that the fridge never turns on so the freezer defrosts. This applies to most 240 volt fridges too, especially fridge freezers in garages and outbuilding.

 

...........Dave

 

 

[Dr Bob]

7 minutes ago, dmr said:

12volt fridges are good things, but certainly not cheap, cabling included . I think they all use the same Danfoss compressor though there might be a Chinese version.

Shoreline and Waeco are the big names but these people look good:

 

  https://www.inlanderlowvoltage.com/             

 

I will certainly consider them when its time to replace the our Shoreline. I think (not sure) that they will also do custom conversions on a mains fridge of your choice.

 

There are two issues with 12 volt fridges on boats:

 

All the cost is in the the compressor and conversion, the base "donor" fridge used by Shoreline is usually a fairly basic model, so its sad to be paying so much for a cheap fridge.

They only use a single thermostat (in the fridge) and boats can go below the minimum operating temperature, especially if left unattended in winter. This means that the fridge never turns on so the freezer defrosts. This applies to most 240 volt fridges too, especially fridge freezers in garages and outbuilding.

 

...........Dave

 

 

Shirley if you were leaving a boat unattended for any period in winter you would turn your fridge off? Especially a 12v one as any interruption in the shore power would drain the batteries. We leave our fridge on (240v) for up to 2 weeks away but a loss of shore power won't affect the batteries.

[Jen-in-Wellies]

On 08/04/2019 at 08:25, curlass24 said:

Also what temperature setting do people run these on?

Depends on too many variables.

• Ambient temperature in the cabin. Putting the fridge at a cool end of the boat is a good idea if you have such a space.
• The flow of air around the cooling coils. I've seen fridges installed so the cooling coils at the back are completely boxed in. There is nowhere for the heat to go being extracted from the chamber, so the compressor is running continuously, trying to bring the temperature down. On my boat, I've got an open path through grills from the cabin bilge, up the back of the fridge, then out in to the cabin via a slot in the back of the work top.
• How old/good the door seal is. If the ice box needs very regular defrosting, then warm moist air is leaking in. Not only makes it harder for the compressor to cool the chamber. Fridges get worse as the door seal ages.

Get yourself a proper fridge/freezer thermometer with external display and set up the fridge thermostat with that. They are only a few quid and save just guessing. Too low a setting and you might get food poisoning. Too high and you are wasting battery charge with what is usually the highest consumer on a boat. Worth setting up properly.

 

Jen

 

Edited April 28, 2019 by Jen-in-Wellies
Double posted.

[dmr]

5 minutes ago, Dr Bob said:

Shirley if you were leaving a boat unattended for any period in winter you would turn your fridge off? Especially a 12v one as any interruption in the shore power would drain the batteries. We leave our fridge on (240v) for up to 2 weeks away but a loss of shore power won't affect the batteries.

 

Yes, but that does mean emptying the fridge and freezer. When we have had just one or maybe two nights away from the boat we have left the fridge on, we have enough battery to run the fridge for several days. It only takes one really cold night to defrost the freezer section.

 

.................Dave

[Dr Bob]

19 minutes ago, dmr said:

 

Yes, but that does mean emptying the fridge and freezer. When we have had just one or maybe two nights away from the boat we have left the fridge on, we have enough battery to run the fridge for several days. It only takes one really cold night to defrost the freezer section.

 

.................Dave

Agreed.

[Kathymel]

I finally got round to dragging the fridge out and measuring the voltage. 

 

With the battery at 12.8v, the voltage at the back of the fridge is 12.6 with the fridge off and 11.7 when it’s drawing. 

 

What does that tell those that know about these things?