By now most are familiar with the problems many of us have experienced with the Flojet/Frigoboat refrigeration water circulation pumps. Several of us who have Amel 54's have noted the very short life of the motors for these pumps when we are in very warm climates. There have been 2 long and potentially confusing threads on this complicated issue, so I decided to create a new one devoted to my solution…………..
The original goal was hopefully a new type of pump driven by a brushless DC motor. Unfortunately, finding a pump with a brushless motor that will work in the Amel service has proven quite elusive, as there are pluses and minuses with every type of pump available. While there are brushless motor-driven pumps out there, they are generally unsuitable, as they are centrifugal and hence need a constant prime. Additionally, some who have tested other types of pumps (gear driven for example) have reported that they are very loud and do not circulate the correct amount of cooling water. Then there is the issue of power requirements. We want a low-current solution.
As a new approach, a few of us have been pursuing a custom brushless motor design coupled to the normal Flojet pump. The Flojet pump is really a good design, as it is quiet and self-priming. Well, I have finally developed a working brushless motor using some of the hardware recommended by Oliver on Vela Nautica. He successfully implemented a brushless motor connected to the Flojet pump through an electronic speed controller, but the missing ingredient has always been the interface to the refrigeration compressors/pump interface.
I now have a prototype functioning system that includes the following components: Flipsky Brushless Motor, Flipsky VESC (controller), and the key component - a mini programmable control board called Arduino. I have not yet built the brackets needed to hold the motor, nor have I yet put all the parts into a small box to install in the engine room. I had to make sure the setup would work first, and I have just now confirmed that.
The motor will be attached to the pump body (cannibalized from the Flojet), eliminating the problematic brushed motor on the pump. Then you will connect the VESC to the motor and program it (using a PC/MAC) with included software (very simple to do through an automated setup and USB connection). And finally, you will connect the Arduino to the VESC and the Frigoboat pump interface (E51385). You have to program the Arduino as well, but again it is quite basic to do so through Arduino software (provided with the controller board). I also use a simple 10K-ohm potentiometer to control the motor speed in real time.
Here is the way my setup is going to work - sorry to have to be so technical, but figuring all this out has been an engineering challenge, and I do not want to overly confuse anyone.
The Frigoboat E51385 sends out a voltage signal (yes it is ultimately 12 volts) to the Arduino (can be direct through a 12V-5V voltage converter, an electronic 12V relay that connects to the Arduino through a NO dry contact, or via temperature sensors inside the refrigeration units). At the moment I am using the relay approach but may shift to temperature-sensor control, as that would allow the Arduino to change the motor speed in response to the fridge temperature(s), which I believe is what Oliver does. The Arduino senses the voltage, contact closing, or temperatures and then turns on the VESC, which then drives the motor at the speed selected by the potentiometer. You would not need the potentiometer if you use the temperature sensors, but that also means reconfiguring the wiring from the refrigeration units and installing sensors in the fridge boxes.
IT WORKS, and the power demand is quite low. Plus, the sky is the limit (with the Arduino), and anything you can dream up is possible with a few extra wires, sensors, and some basic programming. As noted, I still have to install all the components in a box, connect the motor to the Flojet pump body (need to fabricate a bracket of some sort), and mount everything in the engine room. All that is work for sure but not at all technical. Unfortunately, the motor I bought is not the right size to mate with the pump body, and I need to order the right one - yuk.
Once I get everything installed and finalized in my engine room, I will provide a parts list and a schematic for everyone to follow if they would like to make one of these. I will also provide photos so that all this stuff becomes clear.
Stay tuned. I hope to have the final setup within the next couple of weeks or so. If anyone wants to dive in now and get the parts, let me know. I can provide a list of components and better instructions.
Phantom, A54 #44