wingless' Danfoss BD50F / 101N0500 Refrigerator Problems

[wingless]

Originally Posted by Richard Kollmann

RV refrigerators installed in boats operating in warm climates generally need additional condenser and process heat disposal. The first sign of future trouble is high amp draw and can not keep hand on compressor due to heat.

Thanks very much for confirmation of that concern.

My plan is to add a 12V fan adjacent to and aimed at the compressor, so the localized heat created in that still air cavity is moved out, mixed w/ the existing forced exhaust airflow created by the two fans on the refrigerator top plenum, then dumped into the room.

The Danfoss 1010510 controller has a 500mA maximum fan current limitation, so I will construct a small external extra transistor switching circuit to use that controller fan connection to cycle the fan on only while the compressor is running, while only adding a very small amount of additional load current to the controller fan terminal.

[Richard Kollmann]

12 Volt Fan Ideas

Kollmann Marine

[wingless]

Originally Posted by Richard Kollmann

12 Volt Fan Ideas

Kollmann Marine

Great link, thanks.

One topic discussed the high cost of thermostatic fan control.

On my boat I needed a 12V thermostatically controlled engine room heat exhaust.

A $9 digital 12V controller was located on eBay to control two 12V engine exhaust blowers that has been working great for many years. The only negative is that the digital display is only in °C and cannot be switched to °F.

[wingless]

Originally Posted by wingless

My 2000 380 Searay Sundancer was built with a Nocold DE-461 refrigerator. That refrigerator was always a problem and was replaced in August 2009 with a new Isotherm CR187 stainless refrigerator.

This new Isotherm has an excellent design. The refrigerator has a pair of fans to draw fresh room air across the rear-panel condensor coils, then expel that air back into the room, all from hidden front-panel vents that are only visible when the doors are opened. This design permits the refrigerator to be installed into a fully-sealed box.



Isotherm CR187 Refrigerator

Originally Posted by Richard Kollmann

RV refrigerators installed in boats operating in warm climates generally need additional condenser and process heat disposal. The first sign of future trouble is high amp draw and can not keep hand on compressor due to heat.

The documentation for my boat fills a small vertical file soft suitcase. This permits handy access to all of the manuals in one location.

My recent boat service, including repairing this refrigerator, left me w/ a pile of documents to file.

When I got to putting away the refrigerator controller documents I found the original refrigerator manual. It has this information:

isotherm by indel marine
Marine Refrigerators and Boxes

Specifically designed to operate in tough marine environments, isotherm fridges are outstanding in both performance and reliability. Fitted with a fully hermetic, leak-free compressor, they offer the lowest possible power consumption and noise level. All models are extremely simple to install. They can withstand an angle of heel up to 30°, for a short time even more.

[Richard Kollmann]

Originally Posted by wingless

The documentation for my boat fills a small vertical file soft suitcase. This permits handy access to all of the manuals in one location.

My recent boat service, including repairing this refrigerator, left me w/ a pile of documents to file.

When I got to putting away the refrigerator controller documents I found the original refrigerator manual. It has this information:

isotherm by indel marine
Marine Refrigerators and Boxes

Specifically designed to operate in tough marine environments, isotherm fridges are outstanding in both performance and reliability. Fitted with a fully hermetic, leak-free compressor, they offer the lowest possible power consumption and noise level. All models are extremely simple to install. They can withstand an angle of heel up to 30°, for a short time even more.

I see nothing wrong with Isotherms marketing statement but it leaves out quantifying installation application data and performance is generally based on standard day temperatures. Power boats that are large enough for that size refrigerator normally run air conditioning 24/7.

Improving and disposing of refrigerators process heat is always a problem for mobile refrigeration installation engineers.

[wingless]

All good points.

This is an attempted summary and paraphrase of the points for a successful marine refrigerator solution and some diagnostics. Please let me know if corrections or additions are required.

Information was also gleaned from the previously-linked Kollmann Marine website and is paraphrased here.

1. Marine, not RV, refrigerator should be used
2. Proper installation must provide for compressor waste heat removal
3. Proper installation must provide for operational condenser heat removal
4. Proper installation will have sufficient insulation and seals to retain / isolate the cold interior from the ambient environment
5. Proper operation must be in a climate controlled environment, so refrigerator ambient air supply is at normal room temperature
6. Verify installation by measuring compressor case temperature and compressor operational current to ensure both are acceptable, able to touch compressor and under 7A @ 12V for Danfoss system
7. Round trip to battery DC supply wiring must meet or exceed manufacturer's requirements
8. System must be properly designed for operational climate, more effort for proper system operated in tropics
9. Danfoss BD compressor RPM speed resistor selection must be part of a system solution, including ambient temperatures and heat removal
10. Available battery capacity should be 4X expected daily refrigerator consumption
11. The Danfoss BD system permits the addition / usage of a diagnostic LED to determine detected fault codes
12. The Danfoss BD system limits the available continuous fan current to 500mA, disconnection of the fan during a fault removes this as a potential problem source
13. The thermostat on the Danfoss BD system should provide low-resistance continuity when cooling is required, bypassing the thermostat connection with a short circuit removes this as a potential problem source

[wingless]

A pair of tests were conducted to measure the effect of ambient cabin temperature on measured refrigerator parameters.

Note that the battery voltage and refrigerator current were measured using the boat's DC distribution panel's analog meters. The water temperature was measured using the boat's Raymarine instrument. All other temperatures were measured using a Fluke thermocouple thermometer.

Both tests were performed in the southern Florida, tropical climate, with measured exterior air temperature of 90°F and water temperature of 80°F.

Both cabin ambient air tests were performed after the boat interior soaked at the selected ambient temperature for a half dozen hours.

The refrigerator was set to run on DC voltage only, with the AC voltage turned off, so the DC current could be measured.

My refrigerator controller has a 1.48K Ohm series resistor to operate the compressor at 3,500 RPM, instead of the 2,000 RPM selected without the resistor.


Cool Ambient Air Test
Air Conditioner Control Measured / Displayed Temperature: 74°F
Ambient Air Adjacent to Lower Refrigerator Front-Panel Cool Air Intake: 72.0°F
Air Temperature Near Compressor, Lower Rear Corner: 78.5°F
Forced Air Exhaust Plenum Temperature: 83.1°F
Refrigerator Voltage / Current: 13.0V / 6A

Warm Ambient Air Test
Air Conditioner Control Measured / Displayed Temperature: 91°F
Ambient Air Adjacent to Lower Refrigerator Front-Panel Cool Air Intake: 92.3°F
Air Temperature Near Compressor, Lower Rear Corner: 91.1°F
Forced Air Exhaust Plenum Temperature: 95.4°F
Refrigerator Voltage / Current: 13.0V / 6A


There was no measured current difference between cool and warm ambient air temperature operation.

[DeepFrz]

Originally Posted by wingless

A pair of tests were conducted to measure the effect of ambient cabin temperature on measured refrigerator parameters.

Note that the battery voltage and refrigerator current were measured using the boat's DC distribution panel's analog meters. The water temperature was measured using the boat's Raymarine instrument. All other temperatures were measured using a Fluke thermocouple thermometer.

Both tests were performed in the southern Florida, tropical climate, with measured exterior air temperature of 90°F and water temperature of 80°F.

Both cabin ambient air tests were performed after the boat interior soaked at the selected ambient temperature for a half dozen hours.

The refrigerator was set to run on DC voltage only, with the AC voltage turned off, so the DC current could be measured.

My refrigerator controller has a 1.48K Ohm series resistor to operate the compressor at 3,500 RPM, instead of the 2,000 RPM selected without the resistor.


Cool Ambient Air Test
Air Conditioner Control Measured / Displayed Temperature: 74°F
Ambient Air Adjacent to Lower Refrigerator Front-Panel Cool Air Intake: 72.0°F
Air Temperature Near Compressor, Lower Rear Corner: 78.5°F
Forced Air Exhaust Plenum Temperature: 83.1°F
Refrigerator Voltage / Current: 13.0V / 6A

Warm Ambient Air Test
Air Conditioner Control Measured / Displayed Temperature: 91°F
Ambient Air Adjacent to Lower Refrigerator Front-Panel Cool Air Intake: 92.3°F
Air Temperature Near Compressor, Lower Rear Corner: 91.1°F
Forced Air Exhaust Plenum Temperature: 95.4°F
Refrigerator Voltage / Current: 13.0V / 6A


There was no measured current difference between cool and warm ambient air temperature operation.

What was the difference in amp hrs?

[wingless]

Originally Posted by DeepFrz

What was the difference in amp hrs?

The DC amperage was measured and found to be identical at both temperatures.

If the test also measured charge, Ah, or work, Wh, then those would also have been identical.

[DeepFrz]

Originally Posted by wingless

The DC amperage was measured and found to be identical at both temperatures.

If the test also measured charge, Ah, or work, Wh, then those would also have been identical.

No. Ah is amp over time. A lot depends on how much time your compressor is working not just the instantaneous power it draws when it is working.

[wingless]

Okay, the measurements were the instantaneous current measurements.

At this time of year (elevated temperatures) my refrigerator is running about 90% of the time. I have not put an elapsed time hour meter to log the on time, but my approximation is close.

Yes, the cooler cabin temperature from A/C operation will decrease the duty cycle and Ah, but I don't have that data.

Plus, if I were running the A/C, then I either have shore power or I have the generator running, so my refrigerator would be running from AC power and not DC power.

[argus1]

Originally Posted by wingless

Yes, the single screw is removed.

That detaches the box-shaped cavity from the box-frame-shaped compressor side.

There are three round horizontal pins poking out the side of the compressor.

The controller has connector receptacle sockets on the end of a pigtail harness that just slide off the compressor pins.

Can you confirm that there was a screw behind the label that you removed. I am in the process of replacing the controller on a Dometic refrigerator.

[wingless]

Originally Posted by argus1

Can you confirm that there was a screw behind the label that you removed. I am in the process of replacing the controller on a Dometic refrigerator.

Welcome to the forum.

No hidden screw (behind label), just the exposed screw retaining the controller to the compressor.

There is a partial box shaped frame on the compressor, fitting into the box shaped cavity on the controller.

[wingless]

Originally Posted by wingless

...

The trick to installation is to hook the back edge, then rotate on an arc so the front ends up in the correct position, prior to installing the retention screw.

Originally Posted by argus1

Can you confirm that there was a screw behind the label that you removed. I am in the process of replacing the controller on a Dometic refrigerator.

Originally Posted by wingless

No hidden screw (behind label), just the exposed screw retaining the controller to the compressor.

There is a partial box shaped frame on the compressor, fitting into the box shaped cavity on the controller.

It works best to swing on an arc for installation / replacement, after screw removal.