Stainless Lobster Fridge Optimizer

[lawrence_craig]

Hi there,

Has anyone got any experience of using this:

https://seabits.com/save-battery-bee...dge-optimizer/

The Stainless Lobster DC Fridge Optimizer?

I have a digital controller on my DC fridge with high and low setpoints. However I see this also helps with defrosting and circulation which I think would be a positive impact. The author claims a 50% reduction in energy usage but I believe this might be an exaggeration or they had a poor system to start off with.

Thanks,
Lawrence

[a64pilot]

I had one, it did no good at all for my Cool Blue holdover system.
IF you have a thin plate evaporator fridge and IF it has a fixed orifice and IF the compressor isn’t set or high speed by default, then it may be a great thing.
It didn’t work on my Cool Blue for several reasons.
First of course defrost isn’t going to happen on a hold over tank, but I knew that.
Second the Cool Blue compressor is set to high speed already, so it can’t turn the compressor up when there is excess electricity, cause it’s already there.
Third, it doesn’t measure electrical consumption, it’s computed according to what it theoretically is, but as a Cool Blue has a thermal expansion valve, it’s power consumption changes so that the Stainless Lobster doesn’t even come close in energy calculations, it was set to compute the max consumption, and the TXV turns that consumption way down, so the Stainless Lobster read crazy high.
Fourth it only looks at if there is excess energy to turn the thermostat set point lower on start up, so if you have long cycle times, it’s unlikely that it will turn down the set point at the correct time, and of course it will continue to run until that lower set point is reached.
It does this for a quite logical reason, the voltage is lower with the compressor on of course and it only knows voltage at the controller, so it only looks at voltage at start up, cause the voltage will drop when it starts up, meaning that it would constantly cycle if the logic wasn’t set to only look at start up, but it is a very limiting feature.
Also due to the lowering of the set point, in my case it actually increased consumption as of course lower temps take more power to achieve, my system uses less power holding a constant temp.

Then the final problem is that on a hold over system, the thermostat should operate on tank temp, not the air temp inside of the fridge, and of course the Stainless Lobster only sees air temp.

Finally due to the fact that the interface module is not a tight fit to the compressor module, it made intermittent contact, which burnt out my module, so if you use one, remove the module from the compressor, install the interface unit and then put a tie wrap around both holding them tightly together, this will keep good contact, and I believe prevent the module from being ruined.

Now my experience with the Stainless Lobster was less than optimum, but in my opinion it’s because it simply is the wrong tool for a hold over tank system, especially if it has a thermal expansion valve.
It may well be the best thing for a fridge, not a freezer that has a thin plate evaporator and a cap tube, especially if the compressor is set to not run at max RPM by the resistor from the factory.

However after my module got burnt out, I replaced it with the new AEO module, and let me tell you, that was a BIG improvement, and it’s made by Danfoss, for a Danfoss compressor.

So, long story short, what kind of system do you have?

[lawrence_craig]

Some really interesting information in there, thank you.

We have a Bavaria 46 (2007) with the standard plate evaporator in a fridge compartment and compressor tank. The compressor is fixed speed (on/off). Not sure what you mean by fixed orifice?

Thanks.