Re: New Thread on A54 fridge pumps (ATTN: OLIVER Vela Nautica)

Oliver Henrichsen, SV Vela Nautica


1. My brushless pump motors are a lot more efficient than the very basic brushed flowjet motors. Additional the frigoboat box applies PWM to the old brushed motor to convert 24 volts for a 12 volt pump, that adds even more unefficiency to the old system.

2. Reliability: brushless motors are used in places where reliability and 100% duty is required. Like atomic power plants, industry aso. With my conversion we get rid of most of the wear. At Scott we had to use a simple brushless motor because COVID-19 prevented us from shipping our new designed motors with advanved 100% duty marine bearings. 

3. For the boats using RAWwater for cooling, I created a pump version that flushes the tube system automaticaly to prevent silt. 

4. Scott measured 5 liter per minute at 25% motor speed. As the speed is free to adjust, the flowrate can be adjusted to the optimized rate. I run the pump at 30% and higher in flush mode. 

As we are going to convert an other Boat to the new system we will get more data about the energy savings. 

Kingd regards
Oliver from Vela Nautica 

On Mon, Nov 16, 2020, 23:23 Scott SV Tengah <Scott.nguyen@...> wrote:
Second update: I measured the pump flow rate on the original flojet with a hose and bucket and it was 6.5 liters per minute. 

I measured the flow rate on the brushless set at 25% duty cycle and it was a bit over 5 liters per minute. That lower flow rate probably explains some, but not all of the 60% energy savings I am seeing vs. the brushed motor.

Frigoboat literature states that you need to supply 3.8 liters per minute, so even at my lower flow rate, I'm well over the requirement.

What is really odd is that the fridges seem to run better in that they're running less and use less energy. I surmise there may be some truth in Craig Briggs explanation about how warmer water results in more efficient compressor operation. My freezer, which gets cooling water that has been warmed by the first and second fridges, seems to be drawing less energy. Overall, I have a daily power surplus that is greater than the water pump energy savings (with solar output accounted for) can explain.

So far so good. Now let's see if it lasts!

2007 A54 #69
SV Tengah

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