Topics

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


Dean Gillies
 

Hi Porter,
A suitable relay would be something similar to OMRON G2RL1. 

You are correct that a 24V pump operated at12V would deliver about half the volume, and yes the volume is certainly important for the cooling performance.  However, as with medication, the correct amount is best, more than enough is not necessarily better due to side effects (pump wear).

best regards
Dean

SY Stella
A54-154




 

 

 


Rudolf Waldispuehl
 

Hi all  

First I have to say the Fridge-cooling on WASABI is running fine and constantly since 3 years without any issue (living 8-10 Month per year on WASABI). I never replaced the pump and it’s running many hours a day. Nevertheless I bought a spare Frigoboat Pump and a spare controller just in case (see pics).

I have no idea why these pump is always breaking @ other A54. Maybe not using the original pumps? So I hear Bill Rouse saying: “Always use original parts as designed for the boat” ;-)

 

I try to explain what the E51385 is doing in my opinion and excuse me if I bother you with broadly known information. 

-       The Frigoboat E51385 is a DC24-12V converter and power driver to source the needed AMP’s to the pump, because the Fan output F port (which is minus) is not designed to deliver enough Amp’s for the pump on 12V. The E51385 is a Voltage driver (converter) as noted on the schema, which was in my Pump-Box (see Pictures attached).

-       The mentioned schema also shows that if I run a 12V boat Voltage, I can connect the pump with an extra relay controlled by the Fan output, but power-sourced for the pump is the house-battery. Electrically the same as Bill’s proposal. 

-       I opened my spare box and you can see in the middle of the board the blue 12V potentio-meter (or trimmer, - sorry my English is not perfect). It’s the converter regulator to bring any 24V down to 12V. Therefore the Frigoboat controller should never deliver 24V to the pump.

 

I know it’s very confusing that the controller shows the 24V LED on. The LED just indicates; “these is a 24V driven boat”. The LED shows 24V because the Battery Minus goes directly to the E51385. So it shows the 24V between the minus and the plus coming from the FAN-Output (+).  The plus from the Danfos controller is the same plus as the input source and gives 24V against the minus at the E51385. The F wire (-) is only the trigger wire. All together it sounds strange but these 24V is converting to 12V at the E51385 for the pump. Don't be confused with the 24V LED.

Bill’s proposed project is more clear and will certainly run as well. But it’s more or less the same with electrical (discrete components) as the E51385 which is build with transistor components electronically.  In conclusion: 

I don’t think Bill's solution will change the wear of a pump and the problem will stay unless these Frigoboat converters are doing something strange which harms the pumps (but I don’t think so).

Hope this helps a bit to get light into the blue Frigoboard “magic box”, and excuse my limited English.

 

Best regards

Ruedi and Sabina Waldispuehl

AMEL-54 Nbr. 55

Currently in Santa Maria di Leuca 


Dean Gillies
 

Hi Ruedi,
Hope you and Sabine are well, and enjoying sailing once more.

I agree entirely with your description of the Danfoss-E51385 interface.

To make it maybe a little clearer, in our 24V boat the F pin is driven to +12V to enable the pump. Otherwise it floats (is disconnected) electrically. When it is driven to 12V, then the voltage between the + pin and the F pin is 24-12 = 12V. This is what triggers either the 51385 box or Bill's 12V relay. 

As you say, all of this is unrelated to the pump longevity problem. 

Best regards
Dean


Porter McRoberts
 

As with the heart, the condition of the arteries predicts the condition of the pump?
I'm sure we've all changed many an old seawater line. Lime and scale.  Marine atherosclerosis. 
I’m no cardiologist, but surely the resistance in the system would influence pump failure as well.
How might we measure this without a bloodpressure cuff?

I bet we're not 120/80.

Porter McRoberts
A54-152
 

On Jul 10, 2020, at 9:09 AM, Dean Gillies <stella@...> wrote:

Hi Ruedi,
Hope you and Sabine are well, and enjoying sailing once more.

I agree entirely with your description of the Danfoss-E51385 interface.

To make it maybe a little clearer, in our 24V boat the F pin is driven to +12V to enable the pump. Otherwise it floats (is disconnected) electrically. When it is driven to 12V, then the voltage between the + pin and the F pin is 24-12 = 12V. This is what triggers either the 51385 box or Bill's 12V relay. 

As you say, all of this is unrelated to the pump longevity problem. 

Best regards
Dean



Rudolf Waldispuehl
 

Hi Dean, 

You’re absolutely correct with the E51385 Interface. 

 

Yes, all ok on WASABI and hope you both are well doing too. BTW: we will winterize in Spain this year and postponed the Atlantic crossing to next season.

Cheers 

Ruedi


Von: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io> on behalf of Dean Gillies <stella@...>
Antworten an: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io>
Datum: Freitag, 10. Juli 2020 um 15:09
An: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io>
Betreff: Re: [AmelYachtOwners] New Thread on A54 fridge pumps (ATTN: OLIVER Vela Nautica)

Hi Ruedi,
Hope you and Sabine are well, and enjoying sailing once more.

I agree entirely with your description of the Danfoss-E51385 interface.

To make it maybe a little clearer, in our 24V boat the F pin is driven to +12V to enable the pump. Otherwise it floats (is disconnected) electrically. When it is driven to 12V, then the voltage between the + pin and the F pin is 24-12 = 12V. This is what triggers either the 51385 box or Bill's 12V relay. 

As you say, all of this is unrelated to the pump longevity problem. 

Best regards
Dean


Scott SV Tengah
 

Porter - I run freshwater through the pump so scale/lime isn't really affecting me. Pump still dies prematurely.

The Frigoboat UK spec'd pump (4105-343 Flojet) is 24v and flows 3.3gpm. The Frigoboat compressors require 1gpm per the VECO documentation. Per my earlier post from Penguin UK, the concept is that a 24v pump running on 12v will be acceptable for continuous duty - that is not the case obviously.

Rudolf - Mohammad Shirloo, in the Med, has the same longevity as you. Apparently his pump has lasted over a decade. But two things help explain that:

1) Neither of you are full time.
2) Both of you are in the cooler Med.

Oliver said that after he changed the insulation on his galley freezer, his pump was running 15% (or thereabouts) duty cycle in Portugal. Now that he's in the tropics, it's up to 75% duty cycle. This mirrors my experience as my Flojet pump lasted far longer when I was in the Med. 

It appears the combination of higher ambient temperatures and higher water temperatures when he left the Med increased his pump usage by 5x.

Curious - do you run the freezer? We often run two fridges and the freezer. With the three "unsynchronized" compressors, the pump runs nearly 24/7.

And with longer continuous running periods, the brush temp goes up a lot. And above a certain temp, brush wear appears to be exponentially higher. 

Based on this, we are trying to find a brushless solution.


On Fri, Jul 10, 2020 at 7:47 AM Rudolf Waldispuehl <Rudolf@...> wrote:

Hi Dean, 

You’re absolutely correct with the E51385 Interface. 

 

Yes, all ok on WASABI and hope you both are well doing too. BTW: we will winterize in Spain this year and postponed the Atlantic crossing to next season.

Cheers 

Ruedi


Von: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io> on behalf of Dean Gillies <stella@...>
Antworten an: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io>
Datum: Freitag, 10. Juli 2020 um 15:09
An: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io>
Betreff: Re: [AmelYachtOwners] New Thread on A54 fridge pumps (ATTN: OLIVER Vela Nautica)

Hi Ruedi,
Hope you and Sabine are well, and enjoying sailing once more.

I agree entirely with your description of the Danfoss-E51385 interface.

To make it maybe a little clearer, in our 24V boat the F pin is driven to +12V to enable the pump. Otherwise it floats (is disconnected) electrically. When it is driven to 12V, then the voltage between the + pin and the F pin is 24-12 = 12V. This is what triggers either the 51385 box or Bill's 12V relay. 

As you say, all of this is unrelated to the pump longevity problem. 

Best regards
Dean


--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Porter McRoberts
 

All excellent points Scott.
Cold seawater is much better at cooling than warm seawater!!!

We actually installed an air-cooled compressor for the main deep freeze, so its not in the circuit.  That has helped with unsyncronized pump demand, but it does heat up the galley a bit.  

All are waiting for the brushless solution.

Thanks,

Porter/IBIS
A54-152


On Jul 10, 2020, at 4:03 PM, Scott SV Tengah <Scott.nguyen@...> wrote:

Porter - I run freshwater through the pump so scale/lime isn't really affecting me. Pump still dies prematurely.

The Frigoboat UK spec'd pump (4105-343 Flojet) is 24v and flows 3.3gpm. The Frigoboat compressors require 1gpm per the VECO documentation. Per my earlier post from Penguin UK, the concept is that a 24v pump running on 12v will be acceptable for continuous duty - that is not the case obviously.

Rudolf - Mohammad Shirloo, in the Med, has the same longevity as you. Apparently his pump has lasted over a decade. But two things help explain that:

1) Neither of you are full time.
2) Both of you are in the cooler Med.

Oliver said that after he changed the insulation on his galley freezer, his pump was running 15% (or thereabouts) duty cycle in Portugal. Now that he's in the tropics, it's up to 75% duty cycle. This mirrors my experience as my Flojet pump lasted far longer when I was in the Med. 

It appears the combination of higher ambient temperatures and higher water temperatures when he left the Med increased his pump usage by 5x. 

Curious - do you run the freezer? We often run two fridges and the freezer. With the three "unsynchronized" compressors, the pump runs nearly 24/7.

And with longer continuous running periods, the brush temp goes up a lot. And above a certain temp, brush wear appears to be exponentially higher. 

Based on this, we are trying to find a brushless solution.


On Fri, Jul 10, 2020 at 7:47 AM Rudolf Waldispuehl <Rudolf@...> wrote:

Hi Dean, 

You’re absolutely correct with the E51385 Interface. 

 

Yes, all ok on WASABI and hope you both are well doing too. BTW: we will winterize in Spain this year and postponed the Atlantic crossing to next season. 

Cheers 

Ruedi


Von: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io> on behalf of Dean Gillies <stella@...>
Antworten an: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io>
Datum: Freitag, 10. Juli 2020 um 15:09
An: "main@AmelYachtOwners.groups.io" <main@AmelYachtOwners.groups.io>
Betreff: Re: [AmelYachtOwners] New Thread on A54 fridge pumps (ATTN: OLIVER Vela Nautica)

Hi Ruedi,
Hope you and Sabine are well, and enjoying sailing once more.

I agree entirely with your description of the Danfoss-E51385 interface.

To make it maybe a little clearer, in our 24V boat the F pin is driven to +12V to enable the pump. Otherwise it floats (is disconnected) electrically. When it is driven to 12V, then the voltage between the + pin and the F pin is 24-12 = 12V. This is what triggers either the 51385 box or Bill's 12V relay. 

As you say, all of this is unrelated to the pump longevity problem. 

Best regards
Dean




-- 
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Craig Briggs
 

While cold seawater is, indeed, much better at cooling than warm water, it is less efficient for our refrigeration systems. Having the cooling water be at about the condensing temperature of the refrigerant is ideal. Typically, systems are most efficient with 90 degrees F / 32 C sea water (varies with the refrigerant). At much lower temperatures, like 55F/13C up north, the system will operate with a lower suction pressure and the pressure across the expansion valve is reduced which decreases system capacity and increases running times. We've got a gate valve on the sea water outlet that can be partially closed in very cold water to restrict flow and increase temperature. Put your hand on the drier or receiver and it should be about body temp. Recirculating the fresh water in your tank instead of using sea water is great and has the added benefit of keeping the beer cold when you're on the hard. 
Cheers, Craig 


Scott SV Tengah
 

HI Craig,

I'm a little surprised that you're stating that our water cooled Danfoss refrigeration systems perform optimally with water temps above that which we experience in the tropics. That begs the question -  why didn't they design it for maximum efficiency given a water temperature that you would actually experience in the ocean?

My primary concern is pump life, which is directly related to pump duty cycle. Oliver logs his pump duty cycle (fancy computerized system) and noted that it went from 15% in colder waters to about 75% duty cycle when he got to the Caribbean. 

I surmise the hot ambient air temps around the cooling box contribute to that, but for the purposes of comparing pump life for those in warm climates vs. pump life for those in cool climates, pump life seems to be inversely correlated with temperature. Those reporting super long pump lives seem to be in colder areas.

While I don't have Oliver's fancy logging system, I can attest that our refrigeration system uses considerably more power per day and our pumps lasted for much less time when comparing our experiences in the Caribbean vs. the Med. That implies to me that, when all is considered, colder temps mean the system is running less often.

--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Craig Briggs
 
Edited

Hi Scott,
Yes, it does seem a bit counter-intuitive that warmish water is more efficient than cold water. Here is a paraphrase from my system's technical manual that may help in understanding it.

The reason (that 90F sea water is optimum) is that in the refrigeration cycle, after the high pressure liquid refrigerant has passed through the expansion valve and gotten cold by converting to a gas, then passed through the cooling coil and taken on the heat of the refrigerated area and then gone back through the compressor, it is about 140F and only needs to be cooled to about 120F to condense back to liquid and repeat the cycle. Thus 80-90F cooling water is all that's needed. In colder water the liquid refrigerant is too cold and is stored in the condenser and the system operates with a much lower suction pressure as the pressure difference across the expansion valve is reduced. This will substantially decrease the capacity of the system and increase the running
time.

That same manual offers corrective solutions for operating in cold open ocean water by using a gate valve or a water by-pass to restrict the flow of too cold water and get the drier and receiver temperature up to about 95F.

From just an everyday non-technical vantage point, consider that the marine market is absolutely insignificant to the global refrigeration market (no special refrigerants, etc. - there is no such thing as "marine refrigeration" outside of the marketing department). Nobody has cold water cooling - Eskimos don't need it! Household refrigerator cooling coils have ambient temps in the 70's or 80's or more (room temp). Apartments and buildings have water source cooling tower ambient temps in the 80's and 90's (or 100's here in Florida) and, therefore, cooling water temps are the same. Those systems are, in fact, at maximum efficiency because they are providing cooling at the condensing temperature of the refrigerant - 80 to 90 ish, depending on the refrigerant.

And, oh by the way, I just Googled Windy.com, clicked on the water temperature, and from 20 S to 20 N, including the entire Caribbean, the water is in the 80's. At my dock in Florida it's 92F. My A/C and refrigerator love it! As do all those cruisers who used to be there before Covid.

I would assert that no marine refrigeration system is designed to operate in extra-tropical ocean cold water temperatures - unless it has a gate valve or by-pass for cold water use. That pump life has been seen to be inversely correlated to ambient temperature is perfectly understandable. It's not the cold cooling water, it's the cool ambient temperature. The cold cooling water is actually increasing the running time and fighting against the cool ambient temperature that is decreasing the running time. 

It would be fun to experiment with a system with a gate valve or by-pass valve in a cold place. Run the system with 55 degree water for a few days and log the run times.  Then throttle down the valve to get 95 degree water for a few days and log that. Then check Oliver's fancy logging system and see what it shows. Dollars to donuts the warm water will see less pump usage.

Fun topic for a locked down Covid evening, thanks for initiating the discussion,
Cheers, Craig


 

Porter, 

According to Frigoboat, the pump selected should move at least 6 liters/min. A 24-volt pump rated at 12 liters/min. running half speed on 12 volts will pump about 6 liters/min.

I am not the electrical expert that Dean Gillis is, but I will try to answer your question. In this schematic, the relay has a 12-volt coil that activates an internal switch. The switch could switch either 12 volts or 24 volts. In the schematic, you will note that only the positive is switched. Dean, feel free to edit or correct.

That relay in the schematic is a very ordinary "Bosch style" normally open 4 pin relay which uses 2 pins (85 & 86) to activate the coil, meaning when 12 volt positive is connected to 85 and 12 volt negative is connected to 86, a switch is closed between 2 pins (30 & 87). There are 2 types of 4 pin relay available; normally open or normally closed. A normally open relay will switch power ON for a circuit when the coil is activated. A normally closed relay will switch power OFF for a circuit when the coil is activated. You want a normally open relay for this project. To further confuse, there are 5 pin relays which allow either normally open or normally closed depending on whether you use 87 (normally open) or the fifth pin 87a (normally closed).


image.png
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Thu, Jul 9, 2020 at 4:27 PM Porter McRoberts via groups.io <portermcroberts=yahoo.com@groups.io> wrote:
Bill in your schematic,
The relays are 12VDC control and 24VDC load circuit, easy to put a 2-3 amp fuse on the load circuit.
I've searched for this relay and find it quite difficult to find the definitive solution.  Commonly the reverse is found.
I’d like to build a control board for the pumps.
Might you have a source, or nomenclature that would reveal this hidden gem on the web for me?

A second question:  running a 24v pump at 12v, surely spares the pump, but will it affect the pump volume, as the 1.5+ GPH is quite important, yes?

Always appreciated,

Porter
S/V IBIS A54-152

On Jul 3, 2020, at 3:30 PM, CW Bill Rouse <brouse@...> wrote:

Jamie,

I wish I was on your 54 with you because I have a burning question about all of this. and I have a recommendation for you.

My burning question:
If you see the schematic in my previous post in this thread, you will notice the schematic from a Frigoboat manual. The source of the voltage output from the E51385 blue box to the water pump originates in this schematic with each of the Danfoss Compressor Controllers at the F terminal. In fact, the two wires for each fridge unit come directly from the Danfoss to the E51385. The Frigoboat manual clearly states, regardless of the voltage of the fridge the output on the two F terminals is 12 volts. BTW, the Danfoss operates on 12 or 24 volts, but always outputs 12 volts to Terminal F. Have you checked the output voltage on each of the Danfoss on terminal F and the terminal next to it? I do not see any other way that the E51385 blue box can output 24 volts and if there is 24 volts on the Danfoss fan terminals, I suspect something is wrong with the Danfoss.

My recommendation:
Why don't you do this eliminating the E51385 and eliminate the limitation on amps on the Danfoss terminal F, and run a 24-volt pump??:
<Relays to control water pump.jpg>
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Fri, Jul 3, 2020 at 2:02 PM Jamie Wendell <mysticshadow54@...> wrote:
OK, my "final" update on the Flojet pump and Frigoboat E51385  interface. I cannot explain it, but the interface is definitely out-putting 24 volts to the pump at all times.
Maybe my interface is malfunctioning, so I installed a solid-state relay and a DC converter to step the voltage down to 12 volts. I used a 24-volt relay in place of the E
51385 pump connection and then feed the converter and pump via the live 24-volt terminal box in the engine room. The relay simply engages the pump when the compressors call for it.

A bit more complicated than I would like but the pump runs perfectly now and obviously I no longer get the pump overload signals at the interface. The higher capacity pump may draw more power, but it really cools down the 3 refrigerator units fast.

My next task is to get the brushless motor working to replace the Flojet motor. I will drive it directly via the 24-volt terminal block and eliminate the DC converter.

Until then I am "over and out" regarding this perplexing issue with the E
51385. I really appreciate all the suggestions and assistance, but will report once I have the brushless motor controller operational. That will be the gold standard.

Jamie
Phantom, A54 #44




Porter McRoberts
 

Thank you Bill. 
That makes it very clear. Time to head to one of my favorite spots: McDonalds Hardware. 
Appreciated!!
Porter 
A54-152. 

Excuse the errors.  
Sent from my IPhone 
Www.fouribis.net

On Jul 12, 2020, at 10:31 AM, CW Bill Rouse <brouse@...> wrote:


Porter, 

According to Frigoboat, the pump selected should move at least 6 liters/min. A 24-volt pump rated at 12 liters/min. running half speed on 12 volts will pump about 6 liters/min.

I am not the electrical expert that Dean Gillis is, but I will try to answer your question. In this schematic, the relay has a 12-volt coil that activates an internal switch. The switch could switch either 12 volts or 24 volts. In the schematic, you will note that only the positive is switched. Dean, feel free to edit or correct.

That relay in the schematic is a very ordinary "Bosch style" normally open 4 pin relay which uses 2 pins (85 & 86) to activate the coil, meaning when 12 volt positive is connected to 85 and 12 volt negative is connected to 86, a switch is closed between 2 pins (30 & 87). There are 2 types of 4 pin relay available; normally open or normally closed. A normally open relay will switch power ON for a circuit when the coil is activated. A normally closed relay will switch power OFF for a circuit when the coil is activated. You want a normally open relay for this project. To further confuse, there are 5 pin relays which allow either normally open or normally closed depending on whether you use 87 (normally open) or the fifth pin 87a (normally closed).


<image.png>

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Thu, Jul 9, 2020 at 4:27 PM Porter McRoberts via groups.io <portermcroberts=yahoo.com@groups.io> wrote:
Bill in your schematic,
The relays are 12VDC control and 24VDC load circuit, easy to put a 2-3 amp fuse on the load circuit.
I've searched for this relay and find it quite difficult to find the definitive solution.  Commonly the reverse is found.
I’d like to build a control board for the pumps.
Might you have a source, or nomenclature that would reveal this hidden gem on the web for me?

A second question:  running a 24v pump at 12v, surely spares the pump, but will it affect the pump volume, as the 1.5+ GPH is quite important, yes?

Always appreciated,

Porter
S/V IBIS A54-152

On Jul 3, 2020, at 3:30 PM, CW Bill Rouse <brouse@...> wrote:

Jamie,

I wish I was on your 54 with you because I have a burning question about all of this. and I have a recommendation for you.

My burning question:
If you see the schematic in my previous post in this thread, you will notice the schematic from a Frigoboat manual. The source of the voltage output from the E51385 blue box to the water pump originates in this schematic with each of the Danfoss Compressor Controllers at the F terminal. In fact, the two wires for each fridge unit come directly from the Danfoss to the E51385. The Frigoboat manual clearly states, regardless of the voltage of the fridge the output on the two F terminals is 12 volts. BTW, the Danfoss operates on 12 or 24 volts, but always outputs 12 volts to Terminal F. Have you checked the output voltage on each of the Danfoss on terminal F and the terminal next to it? I do not see any other way that the E51385 blue box can output 24 volts and if there is 24 volts on the Danfoss fan terminals, I suspect something is wrong with the Danfoss.

My recommendation:
Why don't you do this eliminating the E51385 and eliminate the limitation on amps on the Danfoss terminal F, and run a 24-volt pump??:
<Relays to control water pump.jpg>
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Fri, Jul 3, 2020 at 2:02 PM Jamie Wendell <mysticshadow54@...> wrote:
OK, my "final" update on the Flojet pump and Frigoboat E51385  interface. I cannot explain it, but the interface is definitely out-putting 24 volts to the pump at all times.
Maybe my interface is malfunctioning, so I installed a solid-state relay and a DC converter to step the voltage down to 12 volts. I used a 24-volt relay in place of the E
51385 pump connection and then feed the converter and pump via the live 24-volt terminal box in the engine room. The relay simply engages the pump when the compressors call for it.

A bit more complicated than I would like but the pump runs perfectly now and obviously I no longer get the pump overload signals at the interface. The higher capacity pump may draw more power, but it really cools down the 3 refrigerator units fast.

My next task is to get the brushless motor working to replace the Flojet motor. I will drive it directly via the 24-volt terminal block and eliminate the DC converter.

Until then I am "over and out" regarding this perplexing issue with the E
51385. I really appreciate all the suggestions and assistance, but will report once I have the brushless motor controller operational. That will be the gold standard.

Jamie
Phantom, A54 #44




Dean Gillies
 

Bill,
That's a nicely packaged set. I like the fixed leads which makes Porter's task easier.
I am 99.9% certain that they will work just fine as you describe.
The 0.1% risk: I could not find any documented specifications indicating that they are rated for switching 24V. Maybe you've seen that somewhere?
Cheers
Dean

Sent from my iPhone X


Dean Gillies
 

Porter,
I like your thinking re BP analogy.
If we take that further... as we can measure arterial flow with Doppler ultrasound techniques, we could use a simple flow meter installed beside the pump to monitor flow rate on an ongoing basis.

I love how this thread has meandered from hydraulics and electrics through thermodynamics and medicine. All relevant and all interesting!

Cheers,
Dean
SY Stella
A54-154

Sent from my iPhone X


 

Dean,
They are rated at 30amps at 12 volts, I think they will handle a lot more amps than wll be needed at 24.
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Sun, Jul 12, 2020 at 5:30 PM Dean Gillies <stella@...> wrote:
Bill,
That's a nicely packaged set. I like the fixed leads which makes Porter's task easier.
I am 99.9% certain that they will work just fine as you describe.
The 0.1% risk: I could not find any documented specifications indicating that they are rated for switching 24V. Maybe you've seen that somewhere?
Cheers
Dean

X