Dometic fridge issue

[matthewbalzan]

 I have a dometic crx65 fridge installed in my boat from 2021. Recently I checked with suppliers and directly with dometic that since I never keep it constantly on more than 8-10 hours ( and I switch off main switches every time I get off the boat), the compressor will take anywhere between 12 and 24 to stabilise and cut off the first time (also my ambient temperature is always 30+ degrees). However, I have also noticed that although it is listed to use 5.5amps, I am finding the fridge frequently consuming between 6 and 6.5 amps. Is this normal in the scenario I explained or does the fridge need some maintenance? Thanks

[nicknorman]

I think it is not surprising that it runs constantly for 12-24 hrs from a warm 30C starting point. As to the current consumption, it may be that the voltage at the fridge is a bit low (due to voltage drop in the wiring). The compressor motor take a fairly fixed amount of power, so if the voltage is lower the current will be higher. Maybe check the specification where it says the current consumption, it may specify the voltage, and it may be that the voltage at the fridge end of the wiring is less than this.

[matthewbalzan]

Thanks for the info. I indeed had a voltage drop problem but beefed up the supply wiring from main switches to fusebox and voltage drop resolved. The 6+ amp load was recorded with battery hooked to 200w panel fully charged at 13.4v... still perhaps normal to have the 6 amp load? 

[Alan de Enfield]

47 minutes ago, matthewbalzan said:

 I have a dometic crx65 fridge installed in my boat from 2021. Recently I checked with suppliers and directly with dometic that since I never keep it constantly on more than 8-10 hours ( and I switch off main switches every time I get off the boat), the compressor will take anywhere between 12 and 24 to stabilise and cut off the first time (also my ambient temperature is always 30+ degrees). However, I have also noticed that although it is listed to use 5.5amps, I am finding the fridge frequently consuming between 6 and 6.5 amps. Is this normal in the scenario I explained or does the fridge need some maintenance? Thanks

 

Fridges are not designed to be turned off every few hours - you are probably (possibly) exacerbating the problem.

Our fridge on the boat goes on and is not turned off for 6 months, at home the fridges and freezers stay on for years.

 

I have the Waeco CR80 and it draws 4 amps, but it is only running for approximately 1/3 of the time (15-20 minutes per hour durng the day, and maybe just a few minutes once, overnight)

Having measured it it is using ~30Ah per day,

 

I did have a prolem when 1st installed that the wiring (from the previous fridge) was too small and it ran almost continuously and didn't get cold.

When we were cruising the fridge worked perfectly and the food in the ice box froze, once the engines were stopped everything started to melt.

 

Obvious problem was voltage drop - so replaced the wiring and never been a problem since.

 

What state are your batteries in ?

Do you keep them charged , how do you know when they are fully charged, what method do you use to charge them ?

Edited July 29, 2023 by Alan de Enfield

[matthewbalzan]

Battery is brand new, wiring thickened to eliminate voltage drop. Fridge works fine gets cold as should be and no problems in that regard. I cannot leave it constantly on as I keep the boat on a buoy not in a marina...so for safety/security i keep mains off when not onboard. What do you think the problem is?

[matthewbalzan]

Forgot to mention that battery is 260ah agm and have a 200w solar panel with mppt. The wiring from the fusebox to the fridge (about 1 metre away) is 4mm as recommended by maker

[Bargebuilder]

My mains fridge, when I first turn it on, drops from 21-23⁰C to it's working 4⁰C in about 15 minutes. I have a digital thermostat to control it so I can watch the temperature drop as I sit drinking tea.

 

Is it possible that your unit needs re-gassing?

 

 

[matthewbalzan]

I am having some doubts now that the fridge needs some maintenance but it does cool down from around 35 degrees to set temperature of 9 degrees in hot Mediterranean weather in about 2 hours which I think is fairly good. My concern is whether using 6+ amps for this is acceptable or not especially since it is rated at max 5.5 amps. If not, the problem could be related to the gas loss you mentioned?

[MtB]

1 hour ago, matthewbalzan said:

Forgot to mention that battery is 260ah agm and have a 200w solar panel with mppt. The wiring from the fusebox to the fridge (about 1 metre away) is 4mm as recommended by maker

 

All this is very interesting but somewhat peripheral. What really counts is the voltage on the fridge connection terminals with the compressor running.

 

Ideally you will be getting at least 12.00 volts. Have measured the fridge terminal voltage while it is running?

 

 

[matthewbalzan]

Yes have measured it and it is exactly as battery measurement way over 12v

[MtB]

8 minutes ago, matthewbalzan said:

Yes have measured it and it is exactly as battery measurement way over 12v

 

I wouldn't expect it the be the exact same as the battery voltage. There would normally be a couple of tenths of volts dropped when the compressor is actually running. 

 

But if you are certain the compressor was running when you got 'way over 12v' at the fridge end, we can rule that out. Also provided the engine was OFF at the time.

[Jen-in-Wellies]

What is the distance, there and back between the battery and fridge? What size wire is used now? Cross sectional area in mm2. The expected voltage drop at 6A can be calculated from that.

[MtB]

4 minutes ago, Jen-in-Wellies said:

What is the distance, there and back between the battery and fridge? What size wire is used now? Cross sectional area in mm2. The expected voltage drop at 6A can be calculated from that.

 

Matthew said a few posts back its "4mm as recommended by maker". Which sounds a bit lacking in detail to me, frankly. 

 

Even if it is 4mm2 cross sectional area, I bet the manual doesn't just say that it adequate whatever the cable length. 4mm2 sounds a bit small to me on reflection, regardless of the length.

[nicknorman]

4mm^2 at 2 metres round trip and 6A is only about 0.1v.

[Jen-in-Wellies]

4 minutes ago, MtB said:

 

Matthew said a few posts back its "4mm as recommended by maker". Which sounds a bit lacking in detail to me, frankly. 

 

Even if it is 4mm2 cross sectional area, I bet the manual doesn't just say that it adequate whatever the cable length. 4mm2 sounds a bit small to me on reflection, regardless of the length.

Thanks, missed that. Yes, 4mm2 is small for fridges, unless the batt is very close by, as @nicknorman says.

[nicknorman]

I suppose the other question is how are you measuring the current? To be honest the difference between the spec and what you are reporting is quite small. Could be a measurement error.

[matthewbalzan]

Sorry for the late reply. Installation manual states that for up to 4 metres round circuit wire from fusebox to fridge wire should be 4mm2 as I have. This was installed by the factory itself, the boat is a beneteau antares 9 2021. I always checked voltage with engine off, even with solar panel disconnected and I didn't find any voltage drop of note..only about 0.1v. 

 

The thing about current measurement is it seems to be increasing by time. For example today as soon as I turned on fridge it was 2.7amp, after an hour or so went up to 4.5amp, after another hour 5.4amp and last I checked after another hour it measured 6.2amp with a clamp meter

[nicknorman]

3 minutes ago, matthewbalzan said:

Sorry for the late reply. Installation manual states that for up to 4 metres round circuit wire from fusebox to fridge wire should be 4mm2 as I have. This was installed by the factory itself, the boat is a beneteau antares 9 2021. I always checked voltage with engine off, even with solar panel disconnected and I didn't find any voltage drop of note..only about 0.1v. 

 

The thing about current measurement is it seems to be increasing by time. For example today as soon as I turned on fridge it was 2.7amp, after an hour or so went up to 4.5amp, after another hour 5.4amp and last I checked after another hour it measured 6.2amp with a clamp meter

Ah I did wonder if it was a clamp-meter. They are not very accurate and have a big thermal co-efficient. Measure the current both ways by flipping the meter round so that one of the reading is negative and one positive. Then take the average of the unsigned values.

 

I think it is not too surprising that the current increases to start with, since initially the compressor isn’t fighting any pressure, then it has to work harder as the pressure increases. But I would have though it would stabilise after a few minutes.

[matthewbalzan]

Thanks for the tip. Yes i also thought it would stbailise but seems other way round...hope no damage is done to the fridge

[MtB]

5 hours ago, matthewbalzan said:

 I have a dometic crx65 fridge installed in my boat from 2021. Recently I checked with suppliers and directly with dometic that since I never keep it constantly on more than 8-10 hours ( and I switch off main switches every time I get off the boat), the compressor will take anywhere between 12 and 24 to stabilise and cut off the first time (also my ambient temperature is always 30+ degrees). However, I have also noticed that although it is listed to use 5.5amps, I am finding the fridge frequently consuming between 6 and 6.5 amps. Is this normal in the scenario I explained or does the fridge need some maintenance? Thanks

 

Reviewing your OP in the light of the subsequent discussion and my own experience with 12V fridges, I find it takes several hours for any of my 12V fridges to stop running after first turning any of them ON. This is in a normal UK environment where the ambient temp is perhaps 18c, so it strikes me as no great surprise that in a 30C environment, yours runs for 12 hours plus. 

 

I'm inclined to agree with Nick too that the current will rise as the cabinet temp drops and the compressor works harder. My own fridges all have the Danfoss BD35 compressor and they start off from warm drawing about 3 Amps according to my Uni-T clamp meter either way around. I've never thought to check again with a cold cabinet though! 

 

 

[Quattrodave]

4 hours ago, matthewbalzan said:

 The wiring from the fusebox to the fridge (about 1 metre away) is 4mm as recommended by maker

 

I take it you mean 4mm². If so that's right on the borderline for exactly 1m of cable.  Personally I would always over spec it, I think you'll be surprised at the difference.

[matthewbalzan]

Thanks for info. Definitely helps to understand better from what you are saying. During the day I have no problem with the load as my solar panel can give up to 11amp which compensates for any equipment I have on at anchor. My worry is during the night as I will have the fridge drawing approx 6a, two 12v fans drawing 1.5a each and some occasional lights...which put me near 10a. My battery is 260ah so should resist a full night with this load until the solar kicks in again. Will test the battery leaving it on for 24 hrs with fridge on and see what happens

[matthewbalzan]

Will have an electrician take a look soon. My fusebox area is so cramped up hope fridge wire can be changed if need be. 

[MtB]

4 minutes ago, matthewbalzan said:

My worry is during the night as I will have the fridge drawing approx 6a, two 12v fans drawing 1.5a each and some occasional lights...which put me near 10a.

 

Are these all supplied by that one 4mm2 cable? Even if not then I too would recommend doubling up the cable at least, given the high ambient temp wherever it is you are! It's an easy thing to do and it rules out thin cable as the cause. Im still not sure why you don't just keep the fridge ON 24/7/365 like wot everyone else does. 

 

 

 

 

[matthewbalzan]

No not on same wire. Each has a dedicated wire from fusebox. I don't keep it on for security purposes especially due to high temperature...i have seen so many accidents caused by fire locally and almost every time due to electrical faults when boats are unattended