Danfoss Designed Control Modules for BD35 and BD50 compressors.

[Richard Kollmann]

I attribute most all of the Danfoss electronic control modules failures are due to poor system application or dirty electrical power supplied to modules. When improper installation application of this compressor causes compressor temperatures and output pressures to exceed normal operating conditions this will over stress the Danfoss control module circuits. The Danfoss BD compressor’s design does not use the conventional safety devices such as high temperature switches or refrigerant pressure cutoff switches, instead it relies on module monitoring of amperage and voltage to prevent compressor from running and exceeding its design limits established by Danfoss.

Having spent the last thirty years in south Florida known as the boating and lightening strike capital of the world where there are three hundred miles of waterway with boats at the docks offer a great test ground for mobile refrigeration. The live aboard boats up to 46 ft most all have 12 volt refrigeration powered by Danfoss BD compressors. Small boats with refrigeration units sometimes use Swing vibrating AC/DC compressors. Because of the moist tropical weather year round many of the thousand of docked boats here keep their Direct Current 12/24 volt refrigerators powered all the time from shore power. Both of my boats had icebox conversion units powered by Danfoss BD compressors that ran most of my 25 years there. It did not take much more than two years to find out that these DC compressors averaging 5 amps when running will cause even a smart battery charger, that keeps battery at full charge, will not remain at float charge rate when compressor starts to run. The end result of using a battery charger or even a smart charger I found battery life was cut in half. To avoid over stressing batteries some boaters use a timer to power charger on and off. I added a sacrificial 12 volt battery and a separate 10 amp charger for both my 12 volt refrigerators when connected to shore power.

The earlier Danfoss BD 2, BD2.5 and BD3 were all fixed speed two field coil brushless motor compressors where the design demanded direct current from the battery. Some one claimed that one field coil was charged the other sent current back to the battery as a reason for Danfoss battery on line requirement so these units must be powered direct from battery.

The newer variable speed Danfoss BD compressors with a different three field coil electronic pulse excitation motor and control module could be operated without the battery on line if you then purchased a separate power supply converter 115 to 24 volts the compressor could be operated on either AC or DC. The BD 35 and BD50 were both capable of running on 12 or 24 volts. WAECO mobile Solutions developed a external AC to DC converter for the BD35 and a larger one for the BD50. Adler Barbour engineer reported problems with this unit. Several companies now use different AC to DC power supply units on Danfoss BD compressors in small cabinet refrigerators.

Any boater that spend much time with boat connected to shore power or has an AC power unit on board should purchase the Danfoss 101N0500 module that comes with a built in AC/DC converter that handles 85 Volts AC to 265 Volts AC in 50 or 60 cycles.
Think of the dollars saved when this $30 additional module cost can extend the life of your house battery bank. This 101N0500 module was introduced in 2005 as an improvement module for BD35 and BD50 compressors only.

I recognize that not everyone will share my preference for Danfross products but after testing 70 to 100 of the Danfoss control modules per year I feel I have enough information to form my opinions on why some modules fail while others last for ever.

If you disagree with my technical positions on refrigeration do it professionally. Please avoid hateful insult mail or change your name and IP address, then I can ignore you.

[Typhoon]

Good write up Richard . I have seen a few bad Danfoss modules . So far just from heat or water damage . This unit below got so hot it popped a capacitor .
This system was water cooled and no fan on the controller. Also it was running on high speed .

I always recommend the installation of a fan over the compressor and controller on a water cooled systems .

Regards John
www.coldeh.com

[NakedCity]

Thank you for that input. I always feared that my batteries we being affected regardless of being told otherwise by 2 separate "charger experts" at last years boat show">Annapolis Boat Show where I posed that very question.

18 months ago I installed 2 Technautics Bulkhead mounted refrigeration units and tried to get them with the ac/dc controller ,but because that controller is physically larger, it would not fit the bulkhead mount units.

Currently replacing my house bank of 4 group 31's. Do you think it will hurt my new house bank if I use the selector switch to select my starting battery ( 1 grp 31)when docked ? My old TrueCharge "Smart Charger" is a 3 bank charger.

[NakedCity]

Originally Posted by NakedCity

Thank you for that input. I always feared that my batteries we being affected regardless of being told otherwise by 2 separate "charger experts" at last years Annapolis Boat Show where I posed that very question.

18 months ago I installed 2 Technautics Bulkhead mounted refrigeration units and tried to get them with the ac/dc controller ,but because that controller is physically larger, it would not fit the bulkhead mount units.

Currently replacing my house bank of 4 group 31's. Do you think it will hurt my new house bank if I use the selector switch to select my starting battery ( 1 grp 31)when docked ? My old TrueCharge "Smart Charger" is a 3 bank charger.

SORRY NOT TECHNAUTICS BUT VERTIFRIGO UNITS !!!!

[Richard Kollmann]

Originally Posted by NakedCity

Thank you for that input. I always feared that my batteries we being affected regardless of being told otherwise by 2 separate "charger experts" at last years Annapolis Boat Show where I posed that very question.

18 months ago I installed 2 Technautics Bulkhead mounted refrigeration units and tried to get them with the ac/dc controller ,but because that controller is physically larger, it would not fit the bulkhead mount units.

Currently replacing my house bank of 4 group 31's. Do you think it will hurt my new house bank if I use the selector switch to select my starting battery ( 1 grp 31)when docked ? My old TrueCharge "Smart Charger" is a 3 bank charger.

First all batteries are not the same. My tests over an 8 year period were with liquid acid group 27 Cosco batteries and a number of chargers.There are a couple of ways to answer your question if your battery's water level is visible in each cell. After two weeks to a month letting refrigeration cycling on thermostat and smart charger was operating. Liquid level in each sell should not change. If battery stress has occurred the liquid level will be lower. 2. Using a voltmeter to confirm Float voltage remains unchanged after thermostat starts compressor. Keep refrigeration off long enough for batteries to stabilize in the low voltage float charge range of 13.2 volts. Now switch on one compressor's power and see if the amp surge causes voltage to increase to 13.8 or higher and then how long will voltage remain there. If voltage remains there as long as compressor runs that is over stressing battery.

Having had engineering responsibility for a large fleet of electrical vehicles and was a member of the electrical vehicle association I believe the amp-hour rating on the day it was made is highest it will ever be. When amp-hrs are removed from a battery all of these amps can not be put back into battery.
It is important to think of a deep cycle battery as a diminishing storage tank based on daily usage and recharging. There was also a theory that if you spent more than a dollar an amp hour for a new deep cycle battery it was going to be a better battery. Today it might cost $3 per amp-hr to get a fairly good battery.

[a64pilot]

I don’t understand how it could hurt batteries?
My Sterling Pro Charge Ultra will pass though if you will any power, in other words any demand up to 60 amps the bank won’t see.
I know this because my battery monitor allows me to see any current passing into or out of the bank, and when the bank is fully charged and the charger is in float, I can look and see no matter what the DC load is as long as it’s below 60 amps the current into or out of the bank is .02 amps + or - never more. It will switch seemingly randomly from plus .02 to minus .02 or sit at zero at times, I believe these small random fluctuations are an anomaly of you will, the the shunt is only so sensitive and .02 is likely outside of its ability to measure current flow.
In fact the Sterling charger is so good it can be used as a power supply, you don’t even need a battery bank as a large capacitor to smooth voltages and current, so if you wanted to You could disconnect the bank.

By the way, I just installed last week the new 101NO390 controller for my BD80. It seems so far to be superior, no fan and it does start slow and ramp up current demand, I’m running it with no resistor between C and T terminals so it’s in AEO mode.
So far also I have not heard any noise in the SSB, the old controller 101NO280 was so noisy I had to turn the fridge off to use the SSB.

Does anyone know if the 101NO280 can be repaired? I’d like to keep it as a spare

[a64pilot]

To not edit my last post, I think the new “Modern” battery chargers are true marvels. Mine when in float won’t change voltage more than .01V when you kick in the fresh water pump that draws 20 amps, or flush the electric head, in fact when I flush the head, first the macerator runs, then the water pump to fill the bowl, then the macerator, then the water pump etc. it cycles both the pump and macerator three times to do a full, non water saving flush, and they whole time the charger is holding exactly 13.3 VDC as measured by my Fluke and it’s own display.
I don’t trust things, especially when they read to the .1V and that reading doesn’t fluctuate, so I checked it long ago. But it really does hold exact voltage even when surging in power over and over.

[dfelsent]

Originally Posted by a64pilot

To not edit my last post, I think the new “Modern” battery chargers are true marvels. Mine when in float won’t change voltage more than .01V when you kick in the fresh water pump that draws 20 amps, or flush the electric head, in fact when I flush the head, first the macerator runs, then the water pump to fill the bowl, then the macerator, then the water pump etc. it cycles both the pump and macerator three times to do a full, non water saving flush, and they whole time the charger is holding exactly 13.3 VDC as measured by my Fluke and it’s own display.
I don’t trust things, especially when they read to the .1V and that reading doesn’t fluctuate, so I checked it long ago. But it really does hold exact voltage even when surging in power over and over.

I have trusted Flukes for 40+ years now. If it works it's a Fluke!

[NakedCity]

Originally Posted by Richard Kollmann

First all batteries are not the same. My tests over an 8 year period were with liquid acid group 27 Cosco batteries and a number of chargers.There are a couple of ways to answer your question if your battery's water level is visible in each cell. After two weeks to a month letting refrigeration cycling on thermostat and smart charger was operating. Liquid level in each sell should not change. If battery stress has occurred the liquid level will be lower. 2. Using a voltmeter to confirm Float voltage remains unchanged after thermostat starts compressor. Keep refrigeration off long enough for batteries to stabilize in the low voltage float charge range of 13.2 volts. Now switch on one compressor's power and see if the amp surge causes voltage to increase to 13.8 or higher and then how long will voltage remain there. If voltage remains there as long as compressor runs that is over stressing battery.

Having had engineering responsibility for a large fleet of electrical vehicles and was a member of the electrical vehicle association I believe the amp-hour rating on the day it was made is highest it will ever be. When amp-hrs are removed from a battery all of these amps can not be put back into battery.
It is important to think of a deep cycle battery as a diminishing storage tank based on daily usage and recharging. There was also a theory that if you spent more than a dollar an amp hour for a new deep cycle battery it was going to be a better battery. Today it might cost $3 per amp-hr to get a fairly good battery.

Thanks Richard I am going to check that out.

[Capt Gill]

"I have trusted Flukes for 40+ years now. If it works it's a Fluke!"

fluke
noun
an unlikely chance occurrence, especially a surprising piece of luck: their victory was a bit of a fluke.

[hzcruiser]

I'm not quite sure what you want to say or who inspired this post, Richard. After reading it at least three times I still don't understand some of the convoluted sentences like this one:

Originally Posted by Richard Kollmann

[...] It did not take much more than two years to find out that these DC compressors averaging 5 amps when running will cause even a smart battery charger, that keeps battery at full charge, will not remain at float charge rate when compressor starts to run.[...]

Would you mind re-reading your posts and splitting up longer sentences, please?


It seems to me as if you're saying that even though the compressor only draws 5A it kills the battery bank in short term even though the boat is on shore power? So the shore power batt charger cannot provide those 5A?
In a later post you mention that if the batt voltage is being raised to 13.8V while the compressor is running, it stresses the batt.

Now, maybe you think the batts are being killed by too high a voltage?

Just trying to clarify what the intention is, here.


On a side note, if thousands of (non-live aboard) boats in Florida have their fridges running all year long every day I would call that a huge waste of energy. Maybe that's just me and I would put in a timer or remotely turn my fridge on Friday evening for the weekend fishing trip...

[Richard Kollmann]

Originally Posted by hzcruiser

I'm not quite sure what you want to say or who inspired this post, Richard. After reading it at least three times I still don't understand some of the convoluted sentences like this one:







Would you mind re-reading your posts and splitting up longer sentences, please?


It seems to me as if you're saying that even though the compressor only draws 5A it kills the battery bank in short term even though the boat is on shore power? So the shore power batt charger cannot provide those 5A?
In a later post you mention that if the batt voltage is being raised to 13.8V while the compressor is running, it stresses the batt.

Now, maybe you think the batts are being killed by too high a voltage?

Just trying to clarify what the intention is, here.


On a side note, if thousands of (non-live aboard) boats in Florida have their fridges running all year long every day I would call that a huge waste of energy. Maybe that's just me and I would put in a timer or remotely turn my fridge on Friday evening for the weekend fishing trip...

Sorry I will break it down for you.

Smart battery chargers are designed to keep battery at full charge. Once battery has reached full charge the charger drops voltage to sustain charge without overcharging battery. This balanced charge voltage is referred to as equilibrium charge or float charge. I believe only a few smart chargers will remain in this equilibrium state when refrigerator starts and runs. If charger design allows voltage to increase to the next control point around 13.8 volts more current is produced than needed by refrigeration. If refrigerator operates on a 30% to 50% duty cycle with excess current pumped in to battery its service life is shortened.
As to the boating life style in south Florida where boaters have boats at their homes cold snacks and drinks onboard in the evenings adds to the great life in paradise.

[a64pilot]

I think maybe that the old “smart” chargers weren’t smart enough so that when a load was applied, it dropped battery voltage slightly, enough so that the charger incorrectly sensed the need to go back into absorption, of course if your kicking in absorption voltage every time the fridge cycles, you are going to kill a battery.

New ones, or at least my Outback 80 on my Solar, my Sterling Pro charge Ultra and my Magnum MS 2812, won’t do that as evidenced by our use of the macerating toilet that cycles both the macerator and the fresh water pump three times for each flush, pulling about 20 amps each time, way more than any fridge would, and all three stay in float and react so quickly that essentially no current comes from the bank on each cycle.

I believe that modern or newer quality charges don’t have that problem anymore, but it does bear watching to ensure your charger doesn’t go back into absorption whenever you hit the bank with a cyclic load like a fridge or bilge pump or whatever.

If it does, then maybe you need a newer, better charger, cause you will for sure be killing batteries and adding a lot of water if they are flooded

[john61ct]

I think with a solid well designed electrical setup, charge sources where setpoints are fully user programmable, top quality batteries designed for up to say a decade of deep cycling

the issue of specifically choosing a 12V fridge system can be made separately from such concerns about bank longevity.

I think it is worthwhile exploring these issues to help optimize how the fridge / freezer cycles, but to maximize energy efficiency while off grid,

not based on the assumption the boat has a substandard electrical system comprising Walmart batteries and chargers designed for automotive use.

Sitting on shore power there should be no challenge at all keeping the House bank costing thousands from cycling unnecessarily, regardless of the refrigeration systems used.

Not saying the issue should not be raised, kuodos to Richard for doing so, but those are two completely separate discussion topics IMO.

Even US RV industry "converters" have been designed for many decades to power the 12V loads without a battery online.

Or just use a 1-2 switch and a circuit with a cheap Starter batt.

[Capt Gill]

Originally Posted by Richard Kollmann

Sorry I will break it down for you.

Smart battery chargers are designed to keep battery at full charge. Once battery has reached full charge the charger drops voltage to sustain charge without overcharging battery. This balanced charge voltage is referred to as equilibrium charge or float charge. I believe only a few smart chargers will remain in this equilibrium state when refrigerator starts and runs. If charger design allows voltage to increase to the next control point around 13.8 volts more current is produced than needed by refrigeration. If refrigerator operates on a 30% to 50% duty cycle with excess current pumped in to battery its service life is shortened.
As to the boating life style in south Florida where boaters have boats at their homes cold snacks and drinks onboard in the evenings adds to the great life in paradise.

Richard, many thanks for the clarification. The thought of having to prematurely replace my two Lifeline 8D's gave me such an adrenaline rush that I straight away went to my boat and checked for voltage/current change during compressor cycling, to my relief there was no change. My charging system is Heart interface 2000 w/ Freedom 25 charger/inverter (pre-Xantrex).