Re: A54 fridge circulation pump

Oliver Henrichsen, SV Vela Nautica

Hi Bill,

I went out for sailing for the last couple of month and was not able to answer the questions that my thread implied. As there is so much response to this topic and I am a bit more station, I will try to point this topic in the right direction.
I am now on Martinique and helping also other boats with technical issues.

In the following I will give answers to your commented questions.

My (Oliver) statements and Bills comments in red. My (Oliver) answers under it. 

  1. He says, "24v batterie directly to the VESC" OK, the new pump motor is running on 24VDC and I assume the Danfoss Controller is no longer used for the water pump.
  2. He says, " The motor/pump speed is open to be controlled from 0 to 100%" I assume by the VESC?      
  3. He says, "My fridge/freezer controller is part of the ship Computer system and connected to NMEA2K bus. The original thermostats are no more used. Instead precise electronic thermometers are in both devices. These still are temperature sensors, or in English, thermostats, and is NMEA2k part of the control system?
  4. He says, "The controller checks on these thermometers and decides about cooling needs." What is the "controller?
  5. He says, "If one unit is above set threshold the controller looks also for the other and if ever possible colls both at the same time. This will further reduce working time of the raw water pump." Is this logic handled by the VESC and does the user set the parameters by connecting to the VESC via the USB connector?
  6. He says,  The controller sends serial commands to the VESC. but the VESC is very versatile so its also possible to regulate it in a simple way."  Again, what is the controller and how is it linked to the VESC
To 1. To understand the setup you need to know the components used:
a) a 24 V brushless pump, as the name says no wear on brushes like before, only the ballbearings wear and they are easy to change and cost 2 usd. Beside that the original quad pumphead is reused. Most of us got a bag of spares from the old worn pumps. I would go with AMELs 24 V as 12V is a step back and we like to have a well powered pump. 
b) A brushless motor needs a driver. In this case a VESC is used to controll the motor. VESC is short for Vedder Electronic Speed Controller designed by a clever swedish guy as open surce project. Version 3.x will do. 
c) to tell the VESC the speed to spinn the motor and start or stop the motor, I use an Microcontroller (MCU)  that sends serial commands. This MCU replaces in my setup the E51385 box and the thermostats in the fridge/freezer because the MCU can do much more than only switch the motor on / off. Its the brain of the cooling installation on my boat and provides advanced efficency. 
To 2. Yes, the VESC controlls the motor speed. 
To 3. NMEA2K is in this stage of the project not used to controll the system. It only provides system data, like temperatures, to other NMEA2K devices as user information. 
To 4. The controller is the MCU described above. 
To 5. This logic is programmed in the MCU that controlls it all. As I said the brain of the system that controlls and comunicates. 
To 6. See description above. The VESC offers, beside the serial port, a second port, where a servo controller can be used. There is no option on the VESC to be switched on/off by 12V or a Relay, its not designed for this purpose. Please read my more simple aproach below. 

I designed a more simple adapter with a bit less efficency but that does not need the MCU. This adapter is hooked up directly to the E51385 Box at the pump connection instead of the pump. 
The adapter tells the VESC to start /stop the pump and adapts the rpm according to the raw water temperature at the raw water manifold. And provides 24 V to the VESC. I guess this is what most owners prefer without need to change the complete cooling controll. It just replaces the brushed pump by a brushless pump and the brushless motor controller. Problem solved. 

Oliver from Vela Nautica Amel54 #39 

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