Fridge Optimizer DC

    250.00 250.00 250.0 USD


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    Pricing Varies Depending on Qty Selected.  For Direct OEM/Distributor Pricing, Contact Us At: [email protected] 


    Never Need to Defrost Again

    Automatically defrosts your fridge at intervals set by you..


    2 Year Warranty

    We’ve got you covered with a 2 year limited warranty against any internal defects.


    precise temperature control

    Automatically keeps your fridge within a set temperature range.


    reduce energy consumption

    Up to 15% less by intelligently adjusting the fridge compressor using an advanced Micro Controller.


    no tools required

    No-tools-required installation with our simple step-by-step guide.



    Compatible with air or water cooled Danfoss and Secop powered refrigeration systems of both cold plate and holding plate design.

    15 %

    Reduced Energy Consumption


    Degrees of Accuracy


    Year Warranty

     Keth, m/v Sojurner

    "Stainless Lobster's fridge optimizer made our unit frost free as well as let us carefully track, monitor and adjust power consumption. We love the product, since we frequently had to defrost our freezer/refrigerator."

     Mark, s/v Nahoa

    "I have been using the fridge optimizer  for over a year now with 100% success and satisfaction. It has revived my old fridge and simplified our lives as liveaboards. We no longer have any issues of temperature being too cold or warm and have had ZERO issues with the product."

     Lisa, s/v Bloom

    "Not only does the fridge optimizer completely eliminate the need for regular defrosts, (which were very time consuming) it also provides invaluable information about our fridge  and allows us to easily control it, first-hand. We absolutely love this product!"

    How it Works

    The heart (brain?) of the Fridge Optimizer is the low power, but very advanced, 8-bit Atmega 328p MicroController Unit, also known as MCU or “Computer on a chip”. The MCU is responsible for monitoring the system and adjusting the compressor and cooling fans based on sensor readings and proprietary algorithms. The MCU also continuously stores and displays real time and historical energy and humidity data. This data shows how much power is being used and if there’s a need to top up coolant or if there’s an issue with the insulation (for example a dirty or worn out fridge door seal). The software running in the Fridge Controller head unit can be upgraded by connecting a PC to the head unit via a USB cable**.

    Complete control at your fingertips

    The Fridge Optimizer’s overview screen gives you an easy, at-a-glance look at what your fridge is doing. It displays the current temperature, the temperature range that you have set, as well as the compressor run status and power status. This head unit can either be flush-mounted on a wall or cabinet, or surface-mounted  via the included stand with 3M holding power. 


    • DC and AC powered Danfoss and Secop powered marine and RV fridges and freezers (BD35, BD50F and BD80F compressors)

    • Compatible with cold plate and holding plate designs

    • Compatible with both air cooled and water cooled refrigeration systems


    Easy installation 

    No tools required! Can be mounted on a flat surface next to the compressor or, on a table or flush mounted anywhere within 30ft* of the fridge.


    optional ventilation

    The Fridge Controller comes with an additional temperature controlled 12V fan output. This is meant to control an optional compressor room fan (sold separately) that we recommend in tropical climates and/or when you wish to take full advantage of the boost mode as Secop recommends a separate fan when running the compressor at higher speeds. We sell a quiet and LED lit 120mm fan that we have tested but any off the shelf 12V 0.25A computer fan can be used.


    Advanced Thermostat

    The Fridge Controller comes with an additional temperature controlled 12V fan output. This is meant to control an optional compressor room fan (sold separately) that we recommend in tropical climates and/or when you wish to take full advantage of the boost mode as Secop recommends a separate fan when running the compressor at higher speeds. We sell a quiet and LED lit 120mm fan that we have tested but any off the shelf 12V 0.25A computer fan can be used.

    Easily Serviced

    The Fridge Controller was developed and built by experienced cruisers and is therefore very easy to service. All cables and the optional compressor room fan can be replaced with parts commonly found in local electronics stores. We recommend using the accessories we sell as we have tested many different brands before settling on the specific models, but fully understand that receiving things in remote locations can be… complicated. We therefore do not limit our support and warranty to just our stock setup. We just ask that you bear in mind that the $1 30ft cable you found on Ebay may not have the same quality as those we recommend and supply. We welcome any questions prior or after install!


    Boost Mode

    The Fridge Optimizer is able to automatically regulate the compressor speed and temperature based on if you’re using the batteries or are plugged into shore power / charging with solar panels or running the engine. This feature helps extend your battery bank and store additional energy in your holding plate.


    2 Year Limited Warranty

    We strongly believe in the quality of our product and therefore offer a 2 year limited warranty against any internal defects. The warranty is limited to the Fridge Optimizer product itself. A receipt (or copy of receipt) from the place of purchase must be included in any warranty claims. Replacement parts may be refurbished. Units in need of service will need to be sent to the Stainless Lobster HQ at your expense. We will cover the return shipping!



    User Manual


    DC Install Manual


    Firmware Version


    Old Firmware Version


    CH340 / CH341 Drivers


    What is the process to update software in the Fridge Optimizer?

    Install on your computer:

    1. Download the software update file here.

    2. Save the file on the desktop of your Windows PC.

    3. Open the update.msi file on your desktop

    4. Windows will complain that it’s downloaded from the Internet…

    5. Select “I understand the risk…” and click “Run anyway”

    6. Windows will now point out the file is from “An unknown publisher”.

    7. Click “Yes” to continue.

    Update device:

    1. Power off the fridge and disconnect the Fridge Optimizer ethernet cable.

    2. Connect the Fridge Optimizer to the PC via a mini USB cable. The port is on the side of the unit, under a small rubber dust cover.

    3. Let Windows locate and install the drivers for the new “Serial Connection”.

    4. Open the Windows Start Menu and locate the “Fridge Optimizer Updater”.

    5. Select the COM port of the newly installed Fridge Controller.

    6. Select the “Hex File” on your desktop, that you just extracted, using the button with 3 dots.

    7. Press “Upload”.

    8. The application will say “Uploading…” followed shortly (20sec) by “##### bytes uploaded”

    9. Done! Unplug the Fridge Optimizer from the PC and re-install the dust cover. Plug the ethernet cable back in and power up the fridge again. Enjoy!

    • Drivers: Windows 10 will find and download the drivers for your Fridge Optimizer automatically. If you have Windows Vista, Windows 7 or Windows 8 (or 8.1) you can download the software drivers from this page: The CH340&CH341 drivers can be found in the Download section of this page.

    • If you have several COM ports and the computer doesn’t determine automatically which one is in use, just start from the top and try all of them until upload succeeds. If upload hangs for more than 30 s. Restart the Updater program and pick the next COM port.

    Yes and no. The super accurate temperature control and dynamic boost options will work but the automatic defrost function will not since it's only designed for refrigerators.

    Yes, but it will not defrost the freezer section.

    Yes it is! The settings can be used to optimize the controller for your specific system. For example, when connected to a system with a holding plate you may want to both run the compressor at a higher RPM and lower the temperature 3 degrees F when you have an abundance of power.

    Can I use the existing Fridge Optimizer with my boat/RV fridge or freezer even though it’s not a model listed as compatible?

    We can’t guarantee it will work with other refrigeration systems (lawsuit disclaimer) but here’s some information that will let you make the decision yourself: The Fridge Optimizer has a number of inputs and outputs that can be used together with other refrigeration systems. The thermostat circuit is isolated through relays and can close any circuit with a load smaller than 1A. What we have seen customers successfully do is connect the “Battery +” and “Battery –“ to 12 or 24V DC and then replace their existing thermostat with the thermostat in and out connections of the Fridge Optimizer. See drawing for connections. Please note that the boost RPM option and the diagnostics LED are unique to Danfoss/Secop compressors and will not work with other brands. 


    The process of defrosting is turning the frost that has built up on the cold plate/holding plate/evaporator into water. To minimize new frost build up and to avoid wet groceries, you should remove this water. ​​If your system has a drain, we recommend leading the water to the drain so it can drip out instead of accumulating. For a closed system we recommend a placing a sponge under the evaporator. This collects the water in once place. Squeeze it out over the sink now and then to keep it absorbent.

    The head unit can be installed up to 30ft away from the connector block. The installation is quite simple but you will need to buy a longer cable. The cable is a standard "40 Ft Cat 5e RJ45 Ethernet" cable. These can be bought for about $10-20 online or at the nearest computer store.

    This depends on the system's design and environment it's operating in. Most marine compressors run between 20% and 70% of the time. Lower is better but sometimes higher is in some cases unavoidable depending on the system and the environment it's in (a large fridge/freezer combo with stock insulation in the tropics will likely run even more).

    Yes, press a button and the screen will light up fully for 2 minutes.The screen will go into a low power mode about 2 minutes after a button was last pressed. This serves two purposes. 1. The head unit uses almost 2/3 less power in the low power state. 2. The head unit isn't lighting up the interior at night.

    There could be many reasons for this. The common thing is that the system is unable to reach the temperature you set as the low temperature cut off. The first thing you should try is to increase the low and high temperature settings in the fridge. They should never be above what's considered food safe temperatures! Here are some other common causes for this problem:

    • You just put warm items in the fridge/freezer and the system hasn't had time to cool those items down yet. Just let is work some more and check back in a couple of hours.

    • The temperature is set to lower than the system is capable of handling. This could be due to the system's design (cooling capability of the compressor and/or insulation thickness)

    • The system has frost or ice on the evaporator. Manually defrost it and then adjust the defrost cycle interval and defrost length. This may require a couple of tries to tune it right for your system.

    • There could be dust on the condenser, not enough air circulation around the compressor or the condenser, a plugged water line (if the system is water cooled).

    • There could be too little or too much refrigerant (R134a) in the system. This is most likely in cases when the system has been serviced recently or not serviced at all in many years.​Please ask a local professional for advice! If you want to learn more there are some really good blog posts about this topic by a gentleman called Richard Kollmann. 

    Start by defrosting the fridge manually so the system starts from a good state. Then adjust the settings for the automatic defrost timer. Navigate to the settings page on the head unit and decrease the cycle time by 2 hours and increase the cycle time by 10min. Leave the system running and use it as normal for about a week. If frost has built up, decrease the cycle time by an additional 2 hours and increase the length by an additional 10 minutes. ​A thin layer of frost build up between defrost cycles is normal. Anything more than a thin layer of frost should be adjusted away as it otherwise decreases the efficiency of the fridge.

    The Fridge Optimizer head unit is powered from the DC side of the Danfoss/Secop controller. You must provide 12 or 24 V power to the controller block. However, the fridge will draw its power from AC, if that is available via shore power/inverter. Note that you will need the AC-DC connector block, so make sure you order the correct model.

    To answer this we must first determine a couple of things:

    1. Where the Advanced Thermostat is placed in relationship to the cold plate/holding plate: If the thermostat is placed very close to the holding plate your will need to lower these values as the temperature there will be colder than in the rest of the fridge/freezer.

    2. What type of cooling system you have: Freezer - this in itself can be broken down into a star rating (European system)

    1. [∗] : min temperature = Low:-5°C High:−3°C (23°F to 27°F). Maximum storage time for (pre-frozen) food is 1 week
    2. [∗∗] : min temperature = −12 °C (10 °F). Maximum storage time for (pre-frozen) food is 1 month
    3. [∗∗∗] : min temperature = −18 °C (0 °F). Maximum storage time for (pre-frozen) food is between 3 and 12 months depending on type (meat, vegetables, fish, etc.)
    4. [∗∗∗∗] : min temperature = −18 °C (0 °F). Maximum storage time for pre-frozen or frozen-from-fresh food is between 3 and 12 months. (This is what you need to keep ice cream hard)Note: A 4 star freezer has 3 inch or thicker insulation to run economically. If you run your 1 star freezer with these settings it will likely use a lot of power.

      Fridge/Freezer Combo- Make sure the Advanced Thermostat is placed inside the refrigeration section, close to the cold plate. Set the temperature as you would for a fridge (starting with: Low:4°C (39°F) and High:7°C (45°F)) and wait 12h and measure the temperature of item inside both the refrigeration and the freezer section. If both sections are too high, lower the temp values by 2 degrees. If one section is too high and one is too low try to find a mechanical adjustment between the sections (an opening that can be partially blocked or an insulating piece that can be used to block the cold plate in the fridge section). Different manufactures use different solutions to vary the temperature difference between the sections.

      Refrigerator- Try running the system with a Low:4C (39F) and High:7C (45F). Measure the temperature of items inside the fridge about 12 hours. If they are too warm, try decreasing both values by 2 degrees and try again. If it's too cold, increase the two values by 2 degrees and try again.


    Nominal Voltage / Operating Voltage Range

    12/24 V DC / 10.8 – 28.8 V DC

    Power Consumption / Fan Power Consumption

    240 mW / 2 Watts

    Physical Dimensions (DISPLAY)

    2.2” x 3.3” x 1.2” (56.5mm x 85.00mm x 30.5mm)

    Mounting Options

    Free standing or flush mount

    Screen Resolution

    128*160 pixels 262K colors


    4.7” x 4.2’ x 4.2” (120mm x 110mm x 110mm) 

    12.1oz (343gr)

    Fridge Optimizer DC