Plan ahead and reduce boat refrigerator down time and repair osts

[Richard Kollmann]

If you are having trouble with your boat’s refrigeration unit, do not call a mechanic. In most cases you can repair it yourself. The most common boat 12 or 24 volt refrigerator compressors are made by Danfoss. These compressors are used by Adler Barbour, Frigoboat, Grunert, Waeco, EZ Kold, Technautics, SeaFrost, Isotherm and several other companies. On Danfoss BD compressors manufactured before 1996 simple tests without tools can be done to isolate the trouble which will allow the boat operator or anyone onboard to correct 90% of possible problems. But if assistance is needed it is available free at http//www.kollmann-marine.com.

After 1995 only Danfoss BD 35 and BD50 energy efficient compressors were produced. One feature on all these new BD compressors is their ability to electronically advise an operator of the location of a problem. A troubleshooting micro processor similar to an automobile’s computer warning light can be installed that will flash a code that will indicate what the problem is. On automobiles an expensive test meter is required to read troubleshooting information, but on BD compressors a simple LED connected to the Danfoss control unit flashes a code. By counting the number of troubleshooting LED code flashes, repeated every four seconds, the item causing the problem will be defined.

There are five different LED signals. They are listed below.:

1.One flash, Boat wiring or battery voltage low,
2. Two flashes fan drawing more than ½ amp.
3. Three flashes, Units amperage too high, someone has tampered with refrigerant.
4. Four flashes, compressor under heavy starting load and can not reach 1850 rpm control speed in time.
5. Five flashes, compressor running under heavy load and module overheating.

Unfortunately these trouble shooting LEDs are not installed on most units. I offer a kit that can be easily installed on the module.
There are installation instruction information at Danfoss and my web site as well as in my 12/24 volt refrigeration manual on Troubleshooting LEDs. If you would like the kit and step by step instructions with pictures, send $8 plus $4 shipping to me and I will mail you a complete kit. This simple device can save you refrigeration down time and hopefully large repair costs. If you understand LED applications and do not need the kit I still provide free refrigeration help on my forum or by email. I can also help with free 3 and 4 pin Control module testing..

Richard Kollmann
Richard@kollmann-marine.com

[skipmac]

Hi Richard,

As always, thank you for the information and support for marine refrigeration systems. I bought your books and spent a lot of time reading on your website and am just finishing the rebuild of my box with 4" of insulation from the original 1 1/2".

Have a Frigoboat system that I will install with a BD50 compressor but all still in the box. Do you know if the Frigoboats include the LEDs? If not I'll sign up for one of yours.


Regards
Skip

[skipmac]

By the way. Just recalled a question I had about my new box. I am plan to re-install the water drain in the bottom of the fridge, suitably plugged and sealed. What sort of caulk would you recommend for sealing the fitting to the bottom of the box? The box is fiberglass, the fitting is some sort of plastic.

[nhschneider]

My boat has two Danfoss BD80 compressors and even though the installation is only four years old, we've had to replace three of the electronic modules so far. None of them have ever had any water or any other liquid spilled into them and there's no other obvious explanation for their failure. At over US$400 a unit, it's an expense we'd like to avoid. Any suggestions?

Thank you for the informative post. We have LEDs on both of our compressors.

Fair winds and calm seas.

[Richard Kollmann]

Skipmac, Unless you purchased the one hundred dollar option on Frigoboat’s BD50 that includes SSC I do not think Troubleshooting LED was included. The easy way to determine if LED is installed is to see if there is a wire connected to Danfoss control module terminal D. If there is nothing connected to terminal D you do not have a trouble code reader LED.
I work with around five boat owners a week on Danfoss compressor problems and more than half go weeks without refrigeration because system manufacturer did not install an inexpensive LED. I wrote this post because a boater up in Northern Florida on way South drove to me in Ft. Lauderdale Saturday to have his module tested. Many boaters call a so called technicians who do not even carry a test LED and they suggest a new system when it is a bad fan that needs replaced.

As far as second question I would only guess that 5200 would stick to both plastic and fiberglass and produce a structurally sound drain fitting.

[Richard Kollmann]

nhschneider , It is always difficult to determine cause of mutable failures without a good understanding of factual history of a system, that said I can give a general answer about Danfoss BD 80 troubles.

Danfoss’s installation application engineering data sheet for BD80 compressors recommends they only be used on Low Back Pressure applications (LBP). This means according to their sheet Evaporator temperatures are to be maintained between -30C to -5 C. This is only possible if refrigerant flow device controlling evaporator temperature can restrict flow when evaporator is warm. Most other BD compressors are approved for HBP, MBP, and LBP but not the BD80

I am not sure of your systems design but if a eutectic holding plate is used and an expansion flow device with too large of an orifice is used Compressors have been reported as failures. I can not remember reports of module failures like you report.

Your module probably has integrated fan cooling AEO speed controller. The two enemies of Dandoss electronic controllers are Heat and Transient voltage Spikes. I am assuming informational warnings I have written covering other module failures may give you something to think about until you can provide mor info on your system.

Short Module Serviceable Life can be caused by how refrigerator was designed and installed.

Danfoss has always experienced problems with electronic control modules on BD compressors. After ten to fifteen different Danfoss module models still randomly failures occur with no warning. If we exclude lightening strikes and corrosion due to water module failures seem to be caused by voltage spikes or heat.

Voltage spikes at module are not always visible with a meter and can be present on any boat. Unstable voltage is why the module must receive power direct from battery buss using correct size wiring, fuses, circuit breaker and switches that allow no voltage drop. When compressor is correctly wired to battery buss battery will absorb voltage surges like a very large electrical capacitor reducing module electronics failures. When refrigerator is powered from a branch circuit breaker panel any item in that panel can cause a damaging voltage spike when that item is powered up or powered down. Any relay when power is turned off sends a voltage spike back towards the source. Windless, power wench, generator start relays and even cabin light relays can damage refrigerator control modules if refrigerator is wired through a circuit breaker panel instead of main buss.

Module overheating maybe the primary reason for so many electronic control module failures. Through the years Danfoss has designed static air heat sinks on modules to conduct and radiate heat away from transistors and other components inside module. Module heat increases as compressor load (amperage) increases. Danfoss’s installation application data sheets have always assumed system designers and installers would insure compressor design power amperage limits were not exceeded. What you will find in the marine industry is the elimination of module and compressor cooling air along with higher than design compressor heat loads. Only Danfoss’s AEO modules have built in module cooling fans. Danfoss’s variable speed specifications for BD50 require an additional fan for cooling control module if compressor is to be operated at maximum capacity (3500 rpm). All of the following conditions can cause module overheat failures; High condenser cooling temperatures, Repeated attempts to start do to an overloaded compressor, First box temperature pull down in a hot climate, System ambient temperatures above 105 degrees F, and too large or poorly designed holding plate evaporator coils. Failure to maintain good cool flow of condenser air, a normal maintenance item, should not be overlooked as cause of module failure.

[gettinthere]

RK, thanks for your info.

I just added an electronic control panel to my seafrost 2 holding plate system.
The AEO setting seemed to be doing a pretty good job of finding a cycle that worked well. But it seemed to get thrown off when we ran the engine drive compressor system. Am I imagining that?

[Sumner]

What address do we use to send a check to or is there a phone number if you take a credit card? Thanks for the info and the product.

You can PM me if you want,

Sumner

[onestepcsy37]

as usual, great advice from richard kollman. i installed a cooling fan (computer fan) that blows directly on to the control module. it already had very good air circulation but i'll sleep better knowing that every time the fridge runs the module is being directly air cooled...

[Richard Kollmann]

gettinthere, The only actual experience I have with Danfoss AEO is in a test room of an electronics company I did some consulting for. Unlike Frigoboat’s SSC there is no indication of compressor speed on AEO so what indication makes you think compressor changes.

I am always concerned about collapsing magnetic fields from coils because they send electrical spikes back to boats electrical power grid. Your engine drive refrigeration compressor clutch when turned off will send a high voltage spike back to its power source. It is important to keep Danfoss refrigeration power source separated from branch circuits and power it direct from main battery busses this then uses battery bank as a spike dampening large capacitor.

[gettinthere]

Cleve gave great input, had me wire the 12 volt compressor direct to the house bank, with breaker inline of course. The engine drive clutch is switched at the main panel.

As to the AEO, it SEEMED to run more often after the engine drive ran. That would seem counter to what you'd think should happen and there are a million variables. I don't have any way of quantifying this, and I could very well be imagining things. Got to stop eating those mushrooms!

[hellosailor]

Richard, if you suspect the electronic modules are failing from power spikes, why not add spike protector to the LED kit? It is another sub-dollar part, your choice of zener or zorb or whichever you think is best, that the customer can put across their power lines at the same time.

[Richard Kollmann]

hellosailor, I prefer to leave Reverse Power Technology to the experts. Danfoss has produced many different module designs and they have always suggested keeping module power and ground source separate from sub distribution busses. People who install 12/24 volt Danfoss systems ignore the idea that trenchant voltages could damage electronics.


I test two to three modules per week at no charge finding 40% in good operating condition. If they were equipped with trouble LED I might get only one module to test a month. If there are repeated failures on the same unit I believe that it is caused by one of two things occurring module over heating or voltage spikes, do I have positive facts to support this NO because I seldom receive feedback when refrigeration later works without failures. In addition to the Kit I help boaters by selling 3 and 4 pin replacement modules at a greatly reduced price.

Module heat failures are much easier to understand either system was poorly designed causing module to be overloaded or system installed incorrectly not allowing enough process heat to be disposed of correctly.

.Hellosailor, What I would like to include with my kit is a voltage switch to close a low amperage circuit at 13.8 volts and open circuit at 12.8 volts. I have recommended in my book a $50 battery combiner be used but I want to include a low cost voltage switch in Kit to increase compressor speed when there is a charging voltage present..

[hellosailor]

Richard, I'm not sure what "Reverse Power Technology" has to do with what I suggested. Spike and surge suppression is a simple enough business, and a single sub-dollar component cheap insurance.

A voltage switch would be a bit more complex, given the variety of 'charging' sources possible on a boat and how an owner might want to configure them. I'm also not sure that you could market one for less than the $50 that battery combiner costs, given that you'd need an IC, a power transistor or relay, a curcuit board, all the bits and pieces. And then how would it increase compressor speed? By switching what? (What it switches could greatly affect the price of what you'd need to build.)

From the heat failures you're seeing, it would seem advisable for owners to buy an inexpensive non-contact IR thermometer, a tool of many unobvious uses, so they can actually check to see how hot that module is running. Or there's the old fashioned way, hold a finger on something and see if it gets uncomfortable.

[Richard Kollmann]

hellosailor, Sorry I thought you might be able to help.