BD Module selection

Danfoss offers a series of special electronic modules for their 12 volt
BD35 BD50 compressor to address differant installation and operating
problems. There are two different modules to hopefully address the
radio noise problem, A soft start module for the BD50, An AC/DC model
to eliminate the battery charger when connected to shore power and
Danfoss's automatic speed control model. Unfortunately they don't
sell one model that has all of these functions. For more information on
this see the current post on my forum at http://www.kollmann-marine.com

Glenn, I would recommend the automatic speed control module described
by Danfoss as Adaptive Energy Optimization module (AEO). Here are
some additional recommendations:
· These units are so quite I would add a green 12 volt LED to the
module's unused fan terminals small + and F.
· All these modules have a chip inside for troubleshooting if a 12
volt low amp LED is connected to module terminals small + and D. A red
LED is recommended here as the only time it will be on is when there is
a problem.
· If you need to add a supplemental cooling fan I would control it
with a inexpensive temperature Snap Disc Control switch available from
WW Granger. I have used there model 2E246, fan turns on at 120 degrees
and off at 110 degrees the objective is to keep the compressors below
130 degrees F if possable, cost $7.

Richard, I would definitely prefer the AEO module but have not found anyone
selling them. R-Parts got a few in and immediately sold out. I even
considered programming my own microcontroller to adjust a digital pot in the
thermostat line to control the speed but decided it would take a lot more
R&D than I wanted to invest. If I find a couple in the future I will swap
out the originals. I figure a couple of spare power modules might rescue
somebody down island one day. :-)

I do plan to add the indicator LEDs. Saw that in the instruction sheet and
wonder why everyone doesn't do it. Thanks for the idea about the thermal
switch. That will definitely go in the system. The exhaust fan will be
buried behind the galley cabinets so it won't make much noise but no reason
to use amps when they are not needed. Think I will stick one on top of each
compressor and wire them in parallel so that if either needs more air the
fan comes on.

Heard so many stories about RFI from these power modules that I am going to
great lengths to suppress it. Lined the compressor compartment with copper
bug screen, adding chokes to the power lines and running all the signal
lines in shielded twisted pair. Hopefully that will help.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

wrote in message
ups.com...
BD Module selection

Danfoss offers a series of special electronic modules for their 12 volt
BD35 BD50 compressor to address differant installation and operating
problems. There are two different modules to hopefully address the
radio noise problem, A soft start module for the BD50, An AC/DC model
to eliminate the battery charger when connected to shore power and
Danfoss's automatic speed control model. Unfortunately they don't
sell one model that has all of these functions. For more information on
this see the current post on my forum at http://www.kollmann-marine.com

Glenn, I would recommend the automatic speed control module described
by Danfoss as Adaptive Energy Optimization module (AEO). Here are
some additional recommendations:
· These units are so quite I would add a green 12 volt LED to the
module's unused fan terminals small + and F.
· All these modules have a chip inside for troubleshooting if a 12
volt low amp LED is connected to module terminals small + and D. A red
LED is recommended here as the only time it will be on is when there is
a problem.
· If you need to add a supplemental cooling fan I would control it
with a inexpensive temperature Snap Disc Control switch available from
WW Granger. I have used there model 2E246, fan turns on at 120 degrees
and off at 110 degrees the objective is to keep the compressors below
130 degrees F if possable, cost $7.

I was present during 105 degree ambient tests of the AEO in freezers
and was impressed with its performance but if you can not find them,
the next best thing is a Frigoboat SSC. I have one on my test bench
and it performs much like the AEO even adjusts for day night economy.
The SSC also has the LED built in including six differant speed LEDs.
There are a series of tests on the SSC in my 12/24 volt book. The BD50
will require a soft start feature if operated at max RPM in a warm
climate, both of these controllers have soft start features.
Dick

The SSC is a good option. Calder did a comparison of the control algorithms
for the Danfoss AEO, Frigbot SSC and the Isotherm ASU in the October 2004
Professional Boatbuilder. Of the three the SSC seemed to have the most
sophisticated program. Works similar to the AEO by monitoring run times and
adjusting speed but the SSC has an "ideal" profile that it tries to fit to
over time. The Isotherm unit really just watches the system voltage and
turns the compressor to high speed when it sees the system is being charged.
Not necessarily the best for temperature control but saves the most battery
amps.

I have an idea for a program that was sort of a blend of all three and could
do a lot more but decided that I didn't want to risk a frige full of spoiled
food because of a programming error. :-)

An interesting side note: I have met several folks who have been cruising
for a long time that complain that their compressors run to long and want to
speed them up when in actuality they are most efficient when they run 59
minutes out of every hour.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

wrote in message
oups.com...
I was present during 105 degree ambient tests of the AEO in freezers
and was impressed with its performance but if you can not find them,
the next best thing is a Frigoboat SSC. I have one on my test bench
and it performs much like the AEO even adjusts for day night economy.
The SSC also has the LED built in including six differant speed LEDs.
There are a series of tests on the SSC in my 12/24 volt book. The BD50
will require a soft start feature if operated at max RPM in a warm
climate, both of these controllers have soft start features.
Dick

The Isotherm ASU system is a progressive speed adjustment based on
evaporator temperature feedback and efficiency adjustments has nothing
to do with voltage. The Automatic Speed Up function is an extra bonus
to the automatic temperature speed control. Advancing compressor speed
when a charging current is available will store additional surplus
energy in the system's holding plate. I do not see how anyone could
believe that the SSC is better than the ASU
from the tests that I have run. I recommended Danfoss's AEO first as
it is a Completely new module. My second choice was Frigoboat's SSC
over Isotherm's ASU for two reasons, Isotherm will not sell their
unit separate you must buy a complete system and the ASU has limited
control when the tropical heat load exceeds its automatic adjustment
range.

Interesting. Calder's article said nothing about the ASU monitoring
anything but system voltage. My thought was that the ideal control would
monitor box temperature, evaporator temperature and cycle time. That way it
could sense when the box had been loaded with warm items and react faster to
frequent opening. Strictly time based algorithms take several cycles to
adjust to changing conditions. Reading the latest Isotherm literature it
looks like the ASU comes pretty close but it seems oriented towards holding
plates. Apparently the ASU replaces the whole power unit where the SSC just
varies the thermostat circuit resistance.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

wrote in message
ups.com...
The Isotherm ASU system is a progressive speed adjustment based on
evaporator temperature feedback and efficiency adjustments has nothing
to do with voltage. The Automatic Speed Up function is an extra bonus
to the automatic temperature speed control. Advancing compressor speed
when a charging current is available will store additional surplus
energy in the system's holding plate. I do not see how anyone could
believe that the SSC is better than the ASU
from the tests that I have run. I recommended Danfoss's AEO first as
it is a Completely new module. My second choice was Frigoboat's SSC
over Isotherm's ASU for two reasons, Isotherm will not sell their
unit separate you must buy a complete system and the ASU has limited
control when the tropical heat load exceeds its automatic adjustment
range.

The reason we want to control compressor speed is to use the lowest
amount of daily onboard power and maintain the box temperature we want
at all times. We by a compressor that can produce the results we want
and generally more capacity output most of the time. Cutting down on
capacity by lowering compressor speed improves SCOP (System Coefficient
Of Performance). Whenever the box temperature can be maintained at the
compressors slower speeds and still have it cycle off the end result
will be fewer daily amp-hrs consumed. What all three of these speed
controllers do is compensate for day night and seasonal temperature
changes. They all will change speed but slowly when warm product is
added to the box. The SSC and ASU both can be set to manual to speed up
the cooling process. I believe only the SSC will provide actual
compressor speeds at the panel. All of these units change the milliamp
flow in the thermostat circuit to control compressor speed.