Dometic CRX110 refrigerator - 12 or 24 volt or both?

[Ian_Edwards]

I'm just fitting a new 12 volt Dometic CRX110 fridge.
I've also bought a MPS35 power supply which should automatically switch to powering from mains whenever 240v is detected.
This is as per the manual, which specifically say use a MPS35.
The MPS35 has a label say for powering a 24volt DC device.
The compressor, a WAECO ACV20, has 12/24 DC (For Controller) on the label.
I'm a little confused, the unit was brought as a 12volt system, but the MPS35 is labelled for 24volts and the compressor is ambiguous with 12/24 volts, is that depending on the version or it can cope with either?
I'm being super careful, I don't want to blow up a new and expensive fridge.
Expert advice please
Cheers Ian

 

[Ian_Edwards]

Update, I got a reply from Dometic, the fridge will run on either 12 or 24 volts, out of the box.
The MSP35 produces 24 volts.
I've the new fridge wired up and running, when operating from the domestic battery bank, the fan speed (noise) is noticeable slower than when it's running from the MSP35, powered by the generator.
At the moment it's struggling to get a full fridge down to 6 deg C, with an ambient temperature of around 22deg C.

 

[coopec]

I have a Dometic Cold machine which runs on 12/24. Somewhere I read it runs better on 24V "as it is too energetic on 12V". I wasn't sure what that meant but I can't find where I read it despite a search.

 

[Ian_Edwards]

The spec' on the CRX110 says rated current, 6.2amps at 12v and 3.0amps at 24v, it a says 50 Watts.
The unit runs a lot hotter and the fan faster at 24v than at 12v, I guess that means it'll cool the fridge fast at 24v, because the heat exchanger is working harder,
I've no idea whether it's more efficient at 12v or 24v, but it would be interesting to find out.

 

[Iliade]

When my (12v) batteries are low, the fan runs a lot but the compressor only runs for brief moments. Consequently the fridge doesn't cool well. When the batteries are full the compressor runs for much longer and the fridge actually cools. Likewise when connected to mains.

However, I had some issues with my, admittedly not brand new, auto-switching power supply - I eventually bypassed the power supply, wiring the fridge directly to the 12V system, because it seemed to be causing a large voltage drop and endless low voltage warnings from the fridge. (red flashing light)

This could be indicative of a tired power supply or too much wire between fridge and battery. (The original system has some 25' of wire between batteries, switch panel and fridge. Supplying the PSU from a short flying lead wasn't much better.)

I have yet to address running it from mains again - I may just let the ship's charger do the work as it is cooling nicely now.

 

[Neeves]

We bought a new Dometic fridge, I don't recall the model, a year ago. We supplemented the compressor fan with 2 computer fans to force the warm air from the back of the fridge, one blows the air across the top, one across the bottom and we draw fresh air from the chain locker. (lots of ducting). The extra fans are wired into the compressor fan, so cycle on with the compressor fan.

I'm not answering your question - simply reiterating advice given on other threads to make a fridge more efficient.

Jonathan

 

[coopec]

We bought a new Dometic fridge, I don't recall the model, a year ago. We supplemented the compressor fan with 2 computer fans to force the warm air from the back of the fridge, one blows the air across the top, one across the bottom and we draw fresh air from the chain locker. (lots of ducting). The extra fans are wired into the compressor fan, so cycle on with the compressor fan.

I'm not answering your question - simply reiterating advice given on other threads to make a fridge more efficient.

Jonathan

Good move forcing air behind the fridge. Some people carry the insulation out to the hull. But water temperatures in a place like darwin can reach
Avg: 31.4°C / 88.5°F