SL Fridge Optimizer, smart new product from a new company

... written for Panbo by Ben Ellison and posted on Feb 2, 2016

Arvid n Annika of_Stainless_Lobster cPanbo.jpgHere are Arvid and Annika Elias as they showed me a prototype of their very first marine electronics product in the press room of last fall's Ft. Lauderdale Boat Show. I was quite impressed and am now pleased to report that the Stainless Lobster Fridge Optimizer is official and shipping. If you'd like better monitoring and control of your boat's electric refrigeration system, and/or automated defrosting (fridge only, not freezer), and/or improved battery time at anchor, read on...

SL_Fridge_Optimizer_overview_aPanbo.jpgHere's an overview diagram of the Fridge Optimizer concept, with the parts that get added to your existing system outlined in orange. The main piece is a small monitoring/control head that plugs easily into the wiring harness of most Danfoss and Secop cooling units, which are used by many marine fridge/freezer companies. You also get an "Advanced Thermostat" module that replaces the thermostat currently in your fridge (and the control knob that may also be in there and thus often hard to set accurately). This module also has a humidity sensor and a small fan to both help even temperatures in the box and speed up defrosting. The exterior fan shown near the battery is optional, but if added, the Optimiser can use it to make the cooling unit more efficient.

SL_Fridge_Optimizer_in_the_box_aPanbo.jpgHere's what comes in the box. At lower right is the Advanced Thermostat module and next left is the clever connector that plugs into your existing cooling unit. You just reattach the existing wires with blade connectors for power and condenser fan (leaving two for the optional exterior fan), and then run the audio style cable into the fridge box for the new thermostat and the Ethernet style cable to the control head. The latter can be freestanding with that back bracket or flush-mounted into a panel with that back flange, which sort of ratchets onto ridges in the sides of the head to accommodate different panel thicknesses.

There's a lot of smart design going on there, I think, and in fact, the display head parts are all "printed" out of a composite material, which is why the front bezel can be had in numerous colors and also partially why this fairly complex product seems reasonably priced at $250 MSRP. Yes, you might notice in the opening photo that Arvid and Annika hoped to introduce it at $199 when we met in the Fall, but they were also smartly trying to get quality distributors involved. The bottom line: If you attend the Seattle Boat Show this week you'll find Arvid showing the Optimizer in the Sure Marine booth (E1101), with Sure apparently offering a show price of $180 and online at $204.

I'll also add that while the Stainless Lobster "about us" page is modest, this couple are deeply experienced tech developers (as well as seasoned cruisers onboard their S/V Inspirare). At our meeting, for instance, they were wearing brand new and beautiful Microsoft Band fitness/tracker/smartwatches because they were both on the development team (before Arvid went full time with their own Stainless Lobster).

SL_Fridge_Optimizer_screens1_aPanbo.jpgFinally, let's look at what the Optimiser can do for us, as detailed in the screens. Note, for instance, that the control head also senses temperature and humidity, so both ambient and fridge values are shown real time and historical. And I, for one, have always wanted access to the info shown middle above -- a day's total fridge run time and amp hours used -- but it's very hard to measure. Heck, sometimes I'd just like to precisely modify the fridge temp without trying to slightly turn a knob that's mounted upside down in Gizmo's fridge and often frozen. But for me the cherry on top is suggested below left. With Optimizer you can set a lower fridge temperature to be applied when the batteries are being charged by engine, shore power or solar panels, and thus use somewhat colder food to reduce cooler unit activity when the battery bank is on its own.

Gizmo does have a somewhat unusual reefer system -- two separate Sea Frost BD coolers, each driving a plate in the freezer side of the box -- but I think there may be a way to make use of a test Fridge Optimizer next summer. The Sea Frost gear has never failed, by the way, and I've sometimes considered adding their optional remote controls and internal fan widgets, but now I suspect that the Optimizer can do a lot more for the money.

Stainless Lobster already has a lot of Fridge Optimiser beta testers -- another good sign -- but maybe we'll hear from new users below. And even if you're completely happy with your boat's refrigeration system as is, I hope you'll give Arvid and Annika a warm welcome to the little world of marine electronics. (I know that they have several other interesting ideas already simmering.)



Thank you for an excellent article Ben! It's an honor to be featured on the page that I go to find the latest cool (and useful) gadgets for our boat!

If anyone has any questions about the Fridge Optimizer we'll be super happy to answer them! Either in person at the Seattle Boat show or here on

Posted by: Arvid at February 3, 2016 12:04 AM | Reply

A very nicely designed product and it seems reasonably priced. I think they would benefit from a compatibility list on their website that shows the models of marine fridges they work with. They may miss out on buyers who don't know the specific compressors they have, and have long lost the manual. The compressor is usually hidden in the back and hard to access to check the model number.

Posted by: Adam at February 3, 2016 1:57 AM | Reply

Agree a list of compatible devices would be helpful. Will they be at Miami Boat Show next week?

Posted by: Scott at February 3, 2016 8:38 AM | Reply

Great idea,

Nothing like eliminating the accumulation of ice via the automatic defrost!



Posted by: Don Joyce at February 3, 2016 9:57 AM | Reply

I completely agree that a compatible device list would be great, as would online access to the quick start guide (which I've seen) and the full manual (coming soon I'm told).

Of course what would be really nice is when and if marine refrigeration manufacturers like Sea Frost offer and support the Optimiser as an option or part of a standard kit. I believe that Stainless Lobster is open to such deals and that the Sure Marine relationship is a good sign.

One compatibility detail that Arvid emailed to me last night follows:

"We have 2 models as Danfoss/Secop has two controllers. They do the same thing, the only difference is the dimensions/spacing of cables on the connector blocks. The DC ONLY model (SLFO-DCDC-122401) is currently for sale and fits into DC only Danfoss controllers:

The AC-DC model (SLFO-ACDC-122401) is being manufactured and will be for sale soon, and fits the Danfoss controllers that take either AC or DC input:

The price is the same for both."

Posted by: Ben at February 3, 2016 10:07 AM | Reply

Excellent feedback! Thank you!!

Regarding a compatibility list:
We've been worried that the fridge manufacturers would get offended if we pointed out that their products could be improved.
I think after hearing your feedback we'll reconsider that stance.

We would love to work directly with the OEMs to add the optimizer as an option to their products! We have ongoing discussions with several manufacturers but have learned that changes to marine and RV products takes time.

We would love to go to the Miami show but we're heads down with increasing production and making more versions of the optimizer that would work with other brands of compressors this month.

Posted by: Arvid - Stainless Lobster at February 3, 2016 1:52 PM | Reply

Do away with the physical display and have the information distributed on boat WIFI and visible on computers and smart phones that are connected to boat WIFI.

Posted by: Dan at February 3, 2016 7:34 PM | Reply

Thanks for your input!
We decided against the wifi/Bluetooth/app approach based on early feedback from cruisers who prefer to have the systems separated and simple.

We have been working on a remote boat management product that connects to wifi (turn on/off heat and lights and get notifications if the boat moves or the bilge pump runs).
We have recently put that project on ice since there are really good systems out there already (see Panbo's review of Siren Marine:
We've talked to Siren Marine and are considering to make the Fridge Optimizer compatible with their system.
Is this something you think would be valuable?

Posted by: Arvid - Stainless Lobster at February 4, 2016 3:59 AM | Reply


The same people that are interested in optimizing their on board systems are quite often also interested in telemetry.

I humbly suggest that solving the data access problem is ideally suited to Signal K. If your device emits Signal K data on a serial port you wouldn't need to add much to your current hardware design, and it would still allow folks that want it to access the data remotely.

For that to happen you would need to enumerate all types of data points and add those to the Signal K model. Read/write (adjusting the controller) could be a second phase.

Posted by: Kees at February 8, 2016 4:48 AM | Reply

So.. I'm going to try two of these out on my 2 Sea Frost units whenever the snow clears in NY. Arvid was very helpful today answering questions.

I agree that a data output would be best (and alarm capabilities). Until then, I'm using a couple of Z-wave sensors to collect temperature data and trigger notifications.

Posted by: Michael Hervey at February 8, 2016 9:53 PM | Reply

Signal K seems like a great option. We'll look into it as a potential communication option shortly.
We have a couple of other things in the pipeline ahead of external communication. Adjustable low voltage cut off being one of the first things on the list (will be delivered as a free software upgrade).

Thank you for your purchase!!
We're looking forward to your feedback on fan position and defrost settings!


Posted by: Arvid - Stainless Lobster at February 9, 2016 9:01 PM | Reply

Quick availability update:
We have been out of stock on all units since the launch at the boat show in Seattle in January.

We now have units compatible with the Danfoss/Secop DC only controllers in stock and will have units for the AC/DC controllers in stock later this week.

I delivered a batch of devices to this morning. They are shipping their back ordered units and are currently updating their inventory to reflect how many they have left in stock.

//Arvid (inventor of the Fridge Optimizer)

Posted by: Arvid - Stainless Lobster at February 16, 2016 7:43 PM | Reply

We've been running the Fridge Optimizer for about a week now in our Isotherm Compact Classic. I think the power savings are much greater than the 15% savings being promoted. So far no frosting of the evaporator. Also, I love the feature that increases cooling when the batteries are being charged. Great product Arvid and Annika!

Posted by: pgudelis at February 18, 2016 10:59 AM | Reply

Thank you so much for sharing!!
It means a lot to us to hear that you're happy with our product!!

Posted by: Arvid - Stainless Lobster at February 22, 2016 10:20 AM | Reply

The AC/DC compatible units are now in stock at Sure Marine:

Posted by: Arvid - Stainless Lobster at February 23, 2016 11:23 PM | Reply

I completely agree with Kees. I already have the Fridge Optimizer installed, and would love that data to be consumable by my onboard SignalK system, and by other systems as well. While I love the Siren Marine system, and other monitoring systems, those are more important for off boat monitoring. While I'm on the boat, I want to have all of the data from every piece of electronics available from any app, computer, or device that is available.

Posted by: Steve Mitchell in reply to Kees at March 2, 2016 5:43 PM | Reply

I haven't installed my Fridge Optimizer yet, but it seems like NMEA2000 connectivity would be superior to Signal K at this point in time. Much simpler wiring as well since my backbone is nearby. Would be nice to get ambient interior temperature and refrigerator temperature on my chartplotter, Maretron display, or any other computing device.

Posted by: Steve Lavigne at March 3, 2016 8:36 PM | Reply

You can use something like

Even video, but in Polish language

Posted by: Kris at March 4, 2016 3:58 AM | Reply

Posted by: Steve Mitchell at March 23, 2016 1:49 PM | Reply

After a couple of months of using the Fridge Optimizer on trips, I am astounded at how this has not been a product before now.

I routinely use 50% or less battery capacity with this little guy installed. Having a more accurate temp sensor, combined with a fan to move the air around and keep things more consistently cold has really paid off!

Posted by: Steve Mitchell at May 10, 2016 5:46 PM | Reply

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