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Data Logger for Refrigeration

Discussion in 'Boat Electronics' started by GBM, Jul 26, 2006.

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  1. GBM

    GBM Guest

    I would like to do some testing on our Refrig unit.

    Minimum would be to monitor icebox temperature and voltage to compressor so
    that I can see on-off cycle and resulting temperature vs time for a 1-2 day
    period.

    If possible, I would like to add current to compressor and temperature in
    area where compressor/condenser is located.

    Since this is just a fact finding test, I would like to keep the cost down.

    I have seen individual USB temperature and voltage loggers at Lascar
    Electronics. For example:

    http://makeashorterlink.com/?V2BD2567D and

    http://makeashorterlink.com/?P5CD2567D

    Does anyone know of a Canadian or US source and especially for a unit that
    might accept several inputs?

    Someone suggested earlier on rec.boats.cruising that I just use a video
    camera, but I need to do this over 24-48 hrs to determine why my refrig
    controller at times seems to go into hibernation!

    Any ideas welcomed.

    GBM
     
  2. Price is right but I don't like the set 30 minute sample rate, the range or
    the 4F accuracy. I (and I think Richard Kollmann) use the Onset Hobo
    dataloggers. For $200 including software it has RH, temperature and 2
    external inputs. More expensive but you would have about the same amount in
    the Lascar units if you want to monitor the same things and a heck of a lot
    more flexible. You can monitor interior and exterior temps, humidity and
    with about $10 of parts cobble together a hall effect current sensor to
    monitor to amps used. Those are the 4 factors you need to monitor
    refrigerator efficiency. You can set the sample period anywhere from .5
    seconds to several hours,accuracy is about +-1F, or 4 times better and the
    battery lasts up to 5 or 6 months.

    Support is really good too. Their tech actually designed the current sensor
    for me and pointed me to where to get the parts.

    --
    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
     
  3. GregS

    GregS Guest


    I have been looking at loggers from these companies.....

    http://www.microdaq.com/measurement_computing/index.php

    http://www.omega.com/vh/hometm.html
     
  4. GregS

    GregS Guest

  5. GregS

    GregS Guest

    of course defrost always screws things up, especially if it is failing.
    I specifically wanted to log the temperature as it defrosts in my use.
    Its bad that manufactures do not offer the refridgerature owner having
    the option to set the defrost, time of day, instead of the way they do it.
    You do not want defrost during usage hours.

    greg
     
  6. GregS

    GregS Guest

    I cannot find the orginal logger I was interested in. I think it was only $40.
    I thought it was from Omega. It had the advantage of specifying delay
    time of sensor, and had the option of exposing the sensor for minimum delay time.

    greg
     
  7. GBM

    GBM Guest

    Thanks - I checked out their site - A bit technical, but it seems that the
    iButton line is aimed at temperature/humidity logging. I would also need to
    know when compressor switches on and off - For this, I would ideally use
    current measurement (0-10A DC), voltage (0-30V) or even something like
    sound. Two temperatures would be better than one.

    Because of this, the buttons made for monitoring transportation
    temp/humidity, may not be the best choice. The multi port dataloggers would
    be great, but cost is a bit high for a one time experiment. There are units
    that interface with a computer that are aimed at school science projects
    that are more reasonable, but my laptops CDROM just failed!

    http://www.drdaq.com/

    I would prefer a stand alone unit for data collection that I can connect to
    my desktop computer for downloading. The Onset Hobo would do the job, but by
    time software and sensors are added, it becomes a bit pricey for a 1 time
    job.

    GBM
     
  8. GBM

    GBM Guest

    Some of the dataloggers have the possibility of monitoring an event such as
    a switch on/off, but not all.

    I think I have finally come up with a simple method - I will just use two
    independent temperature loggers. One in the ice-box and one just above the
    condenser fan. The latter will get an upward spike in temperature when the
    compressor comes on. This way, I should be able to plot box temperature vs
    compressor on/off cycle. This should do it.

    Thanks for the input.

    GBM
     
  9. A much better idea would be to find a datalogger that can monitor 0 to 5VDC
    and an amploc hall effect current sensor.
    http://www.ampsense.com/AMP25.html These things cost about $5 and need a
    stable 5V power source like an Artesyn AFC5-12S05F, 2 little resistors and a
    small capacitor. Loop one of the compressors power lines through the sensor
    and you can monitor not only when it turns on but how many amps it is
    drawing. With that information you can adjust the speed of the little
    Danfoss compressors to get the most cold for the least amps.

    If you can't find the Artesyn you can have one of my spares for $12.

    --
    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
     
  10. GBM

    GBM Guest

    Thanks for the offer Glenn!

    I did consider this approach, but because I am just troubleshooting on a
    1-time basis, I am trying to keep the cost down! The Hobo unit becomes
    expensive because of the software cost as do several of the other makes. I
    don't really need current logging. I have borrowed a Kleton AC/DC clamp on
    meter that will allow me to check out startup & run current.

    I am thinking about just buying two of the button type temperature loggers
    but even that will cost US$120.00 or so. Something that would display and
    log icebox and condenser fan exit temperature would probably be more useful
    in the long term - still looking for this! I do already have a display using
    a wireless indoor/outdoor thermometer, but no logging.

    GBM
    GBM
     
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