Calder's Boatowner's Mechanical and Electrical Manual

[Donsan]

I have the 2005 update version of Calder's boat bible. At the end of chapter 2, he has a section that deals with emerging technologies such as fuel cells, brushless DC motors and generators and then electric boats.

Okay, here we are 10 years later and from what I can tell, none of these have really made it out of the starting gate. Are any of the manufacturers making marine products with brushless DC motors? Could you provide some examples?

 

[BlueYonder]

The Torqeedo electric outboard motor uses a brushless motor

 

[dimer2]

SPX (Johnson) water pumps. Some windlass's, normally large ones. Fuel cell generators are available but IMO have a long way to go to be viable. As FF points out, we are but a small market.

 

[Paul Swanson]

I have the 2005 update version of Calder's boat bible. At the end of chapter 2, he has a section that deals with emerging technologies such as fuel cells, brushless DC motors and generators and then electric boats.

Okay, here we are 10 years later and from what I can tell, none of these have really made it out of the starting gate. Are any of the manufacturers making marine products with brushless DC motors? Could you provide some examples?

Fuel cells are great devices which produce electricity directly and the only byproduct is water, which conceivably could go into your water tanks. They are used experimentally in some automobiles. However, they burn hydrogen which is not so easy to find at your local marina. The hydrogen has to be stored at extreme pressures (> 5000 psi) or as a cryogenic liquid at around 30 Kelvin. The boil-off rate makes it impractical for a boat that is used only a few times a month. They may never be widely used for recreational boating.

Paul

 

[Donsan]

What I was hoping to find is the use of brushless motors in generators and air conditioners.

 

[Xsbank]

You can buy brushless alternators...

 

[FF]

"What I was hoping to find is the use of brushless motors in generators and air conditioners."

Seems better DC inverter tech has cooled the need.

EG. Danfoss refrigeration pulse the rotor for best electric use.

The Mirsubishi split air cond is advanced tech, but its only a few % better at cooling , way!!! better at heating.

Its hard to tell a CEO, your paid for factory needs to be replaced .

Only when they have seen their market shrink are they willing to change .

 

[David O]

My Onan generator is a 2006 and it is brushless. It uses 2 sets of orbital diodes. Is that what you are referring to?

 

[Donsan]

My Onan generator is a 2006 and it is brushless. It uses 2 sets of orbital diodes. Is that what you are referring to?

Could be. Perhaps I am being thrown by terminology. Calder is calling them Brushless DC (BLDC) generators and Onan is calling them Brushless alternators. Kind of suspect Calder's use of BLDC isn't very intuitive to make his point. I will reread Calder's explanation and hopefully it won't be as confusing second time around.

 

[Nomad Willy]

Generators need to be turned quite fast to make much power. Would that be true of brushless generators as well?

 

[Donsan]

Generators need to be turned quite fast to make much power. Would that be true of brushless generators as well?

Not according to Calder. On page 66 he cites several BLDC benefits including:
1. Almost no inrush currents.
2. Operation at variable speeds and loads
3. Don't require fixed output frequency
4. Will accept variable input voltages
5. Smaller size and weight
6. Higher electrical efficiency

 

[FF]

1. Almost no inrush currents.
2. Operation at variable speeds and loads
3. Don't require fixed output frequency
4. Will accept variable input voltages
5. Smaller size and weight
6. Higher electrical efficiency

Almost all these advantages already exist in the "old style" AC -DC motors with brushes. Sure the brushes can wear eventually , no big deal.

Anyone with an old AC-DC chain saw working on a long extension cord has seen the advantage.

Disadvantage? , initial cost to build.

 

[Donsan]

1. Almost no inrush currents.
2. Operation at variable speeds and loads
3. Don't require fixed output frequency
4. Will accept variable input voltages
5. Smaller size and weight
6. Higher electrical efficiency

Almost all these advantages already exist in the "old style" AC -DC motors with brushes. Sure the brushes can wear eventually , no big deal.

Anyone with an old AC-DC chain saw working on a long extension cord has seen the advantage.

Disadvantage? , initial cost to build.

After doing some research into generators...errr noisemakers, I have found most of the manufacturers such as Onan, Northern Lights, and Westerbeke are now using brushless motors. It isn't advertised as a selling point but the technical advantages of using BLDC motors are advertised as inherent to the generator and today's gennys seem to have a lot of advantages over my 30 year old beast despite the best efforts of the clean air crowd. There does seem to be some admission that under full loading, there is little to be gained by BLDC but I have read posters over and over complain of having to put unnecessary loads on their generators and that is not necessary with BLDC.

Cost to build may not be much higher since BLDC motors are smaller but they do require some electronics. I would guess the real cost driver is the cost of copper versus the cost of the rare earths for the permanent magnet.

 

[FF]

"There does seem to be some admission that under full loading, there is little to be gained by BLDC but I have read posters over and over complain of having to put unnecessary loads on their generators and that is not necessary with BLDC."

Most Diesel engines need to be loaded to a certain minimum point to avoid early death.

The modern Gas noisemakers ( like Honda 2000, 3000)get by with a variable speed setup , where the engine is efficiently loaded , even at low RPM by the electronics.

The use of brushes or not in the gen head is not going to change the loading requirement of a diesel engine, or lack of efficiency when barely loaded..

When the diesel noisemakers operate with the gas engine practice of matching the RPM to the load , and making 60CPS with electronics , we will have advanced.

It WILL be possible to run a battery charger and the fridge (with almost no noise) just above idle , and have a long service life.