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Old 02-01-2018, 10:55   #1081
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Re: Oceanvolt Hybrid Motor

The idea that electric motor technology “is advancing very rapidly indeed” is not accurate. The technology in motors, controllers and batteries has been mostly stagnant for years. Motors and generators are about as efficient as they are going to ever get. Same for motor controllers.

What is advancing is engineering out cost and adding features. But these are not technology breakthroughs.

When a diesel motor turning a generator (AC or DC) which in turn is powering an electric motor can be more efficient (in nautical miles per liter) than a simple diesel with gearbox that will be a technological breakthrough. Don’t hold your breath.
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Old 02-01-2018, 13:19   #1082
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Re: Oceanvolt Hybrid Motor

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The idea that electric motor technology “is advancing very rapidly indeed” is not accurate. The technology in motors, controllers and batteries has been mostly stagnant for years.
For batteries this is not correct. The world is investing and working intensively for improvements in this field (especially automotive industry) and the effects you can see in the significant improvements of weight, capacity and cost. Every year it gets quite a bit better! Look for example at the 36 kg/5kWh battery mentioned earlier in this thread.

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When a diesel motor turning a generator (AC or DC) which in turn is powering an electric motor can be more efficient (in nautical miles per liter) than a simple diesel with gearbox that will be a technological breakthrough. Don’t hold your breath.
This is correct when you look at a (very?) good working point for the conventional diesel propulsion system. However, if you are motoring under sub-optimal conditions (torque and rpm) a hybrid system can be equally efficient or better.
Use cases requiring highly dynamic operation, such as tug boats, are for example better off with a hybrid electric propulsion. As batteries get better, the efficiency of energy in/energy out will get better too, allowing for more efficient operation with intermittent genset runtime.
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Old 02-01-2018, 14:19   #1083
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Re: Oceanvolt Hybrid Motor

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But EV fans tell us that electric motors are so reliable because they have fewer parts.

Electric motors and controllers are not a new idea, so no reason to expect a sudden massive improvement in reliability.
I've known fridge motors made in the 80's that thought nothing of stopping and starting for 20 years. So you are right - no room for massive improvement in reliability.
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Old 02-01-2018, 14:31   #1084
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Re: Oceanvolt Hybrid Motor

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The idea that electric motor technology “is advancing very rapidly indeed” is not accurate. The technology in motors, controllers and batteries has been mostly stagnant for years. Motors and generators are about as efficient as they are going to ever get. Same for motor controllers.
Electric motors are not only about efficiency in terms of power in & out. Google "progress in electrical motor size and weight" it is quite impressive. Many people are working on it and there is still room for progress.

As for motor controllers, I think tesla's ludicrous mode proves you wrong. It's not been so long that the high end makita products are BLDC as another example.
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Old 02-01-2018, 14:39   #1085
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Re: Oceanvolt Hybrid Motor

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For batteries this is not correct. The world is investing and working intensively for improvements in this field (especially automotive industry) and the effects you can see in the significant improvements of weight, capacity and cost. Every year it gets quite a bit better! Look for example at the 36 kg/5kWh battery mentioned earlier in this thread.



This is correct when you look at a (very?) good working point for the conventional diesel propulsion system. However, if you are motoring under sub-optimal conditions (torque and rpm) a hybrid system can be equally efficient or better.
Use cases requiring highly dynamic operation, such as tug boats, are for example better off with a hybrid electric propulsion. As batteries get better, the efficiency of energy in/energy out will get better too, allowing for more efficient operation with intermittent genset runtime.

Batteries are pretty close to 100% efficient in/out right now. At least in the mid 90’s for Lithium Ion. Tesla claims 98% under certain conditions. The main improvement in batteries will be weight, charge time, service lifetime and fire prevention. But not charge/discharge efficiency.

Railroads use diesel/electric because the engineering makes sense. But we aren’t talking in this thread about tug boats or railroad locomotives. We are taking about low power (<100kW) cruising boats.

I think electric propulsion for boats is great. There are many advantages over diesel. But I wish the proponents would just accept that electric is not as efficient nor more reliable than plain old diesel + gear box. And they need to forget this goofy fallacy that an electric kW can make a boat go faster than a diesel kW. That’s all it would take for many of us to take electric purveyors more seriously.
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Old 02-01-2018, 15:26   #1086
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Re: Oceanvolt Hybrid Motor

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I think electric propulsion for boats is great. There are many advantages over diesel. But I wish the proponents would just accept that electric is not as efficient nor more reliable than plain old diesel + gear box. And they need to forget this goofy fallacy that an electric kW can make a boat go faster than a diesel kW. That’s all it would take for many of us to take electric purveyors more seriously.
I'd say true enough for long distance cruising. But day sailers and harbour hoppers who choose their weather and have a mooring or berth to come back to to electric.
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Old 02-01-2018, 15:36   #1087
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Re: Oceanvolt Hybrid Motor

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As an engineer when the calculations and the empirical data are drastically different, you look for what is different between the two methods.

As the only ones showing supposedly empirical data is the marketing department, it is questionable. If it was true, I would expect them to be pulling in independent sources to confirm. Boating magazines for example would be all over it if it was so good.
Well, that's clearly not the case here so not relevant to my comment.
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Old 02-01-2018, 15:51   #1088
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Re: Oceanvolt Hybrid Motor

Speaking of Kato, I saw her yesterday looking very nice in Sydney Harbour. Tony must have been down for the fireworks
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Old 03-01-2018, 04:07   #1089
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Re: Oceanvolt Hybrid Motor

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I've known fridge motors made in the 80's that thought nothing of stopping and starting for 20 years. So you are right - no room for massive improvement in reliability.
And I've had ICE motors with similar results. A pair of 1979 Chrysler 360's I had until the mid 2000's that just got an annual oil/filter change but otherwise ran great with no extra work. My last truck was a 1992 diesel with almost 300k miles. The rest of the truck was falling apart but again other than an oil change about once a year, it just ran.

Of course a fridge doesn't include variable speed controllers, charging systems, battery banks, etc...
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Old 03-01-2018, 14:48   #1090
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Re: Oceanvolt Hybrid Motor

A New Years Prediction

This year, there will be more and more actual installations of EP on cruising boats, mainly catamarans as far as I can see. That's not such a startling prediction, is it?

But following the sea trials of these boats, you will see more and more actual use cases of electric motors that produce the same motoring performance as kW to kW bigger sized diesels.

I also predict that the data from these boats will comprehensively show that the "EP deniers" on this and other forums are, and have always been, totally wrong in their various statements that electric motors of a smaller kW continuous rating can deliver the same motoring results as a diesel somewhere between twice and three times the kW rating of the electric motor.

Let's see if I'm right. The case of Kato is a strong indicator, but I grant that it takes more than one example to give a meaningful result.

Another quick prediction: Despite the evidence of the actual test data, the EP deniers will still deny that it is reality. They will cite any number of spurious reasons why this is not true, basically anything that they can grasp onto to support their confirmation bias, but the reality will be obvious to objective observers.

However, as always, I welcome their actual test data that proves their case.

I would even go so far as to give the test case that would settle this once and for all. The definitive test case would be 2 boats the same design, at the same displacement, one with 15kW electrics, one with 30kW diesels, motoring side by side in flat calm conditions. Then, same boats, motoring into the same stiff wind. Both videotaped simultaneously.

Of course, then we will hear cries that "It was rigged!!!"

Happy New Year
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Old 03-01-2018, 15:21   #1091
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Re: Oceanvolt Hybrid Motor

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Of course, then we will hear cries that "It was rigged!!!"
IMO, simply by making this statement, you show that you yourself are biased, just in the opposite direction.

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Old 03-01-2018, 15:36   #1092
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Re: Oceanvolt Hybrid Motor

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IMO, simply by making this statement, you show that you yourself are biased, just in the opposite direction.

Jim
Considering that's what he's copped the whole thread I think you're being extremely harsh and unfair. IMO.
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Old 03-01-2018, 15:41   #1093
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Re: Oceanvolt Hybrid Motor

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Originally Posted by transmitterdan View Post
The idea that electric motor technology “is advancing very rapidly indeed” is not accurate. The technology in motors, controllers and batteries has been mostly stagnant for years. Motors and generators are about as efficient as they are going to ever get. Same for motor controllers.
mosfets are getting lower on resistance all the time. The other electronics also are lower power. This improves controller efficiency. It is a small gain in the total system, but has not reached a limit.

Mostly electric motors have peak efficiency at only specific loads, this can be improved.

A lot of ideas have not been tested. Different winding configurations, different phase counts, new alloys... Clever ideas that haven't been though of yet! A controller that can drive the same motor in both delta or wye as needed.

There are thousands of parameters like these that have conflicting requirements and not all combinations have been tested. The gains might not be huge as the motors are already relatively efficient, but they have not reached a limit yet.

As you say, reaching the efficiency of a mechanical gear box, electrically has not been reached yet, but theoretically it can be, at least in some cases (I would imagine higher gear ratio)
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Old 03-01-2018, 17:08   #1094
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Re: Oceanvolt Hybrid Motor

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Considering that's what he's copped the whole thread I think you're being extremely harsh and unfair. IMO.
Your opinion is worth about the same as mine...

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Old 03-01-2018, 17:28   #1095
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Re: Oceanvolt Hybrid Motor

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Your opinion is worth about the same as mine...

Jim
Exactly. However, when you consider that he's shown video of actual numbers that Tony has achieved on Kato that people are saying is just marketing BS then my point is made for me.

So, he's just heading off at the pass what he's already had to deal with.
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