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Old 10-12-2018, 15:59   #1486
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Re: Oceanvolt Hybrid Motor

If I may offer a suggestion, it may help the conversation here to have a set of working assumptions that you copy and paste into each post so everyone understands the context the comments are made within.

Then the focus can be on the actual discussion and not a lot of clarifying and back forth.

Maybe even state, roughly, a couple of real systems to compare or use as a starting point?
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Old 10-12-2018, 16:08   #1487
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Re: Oceanvolt Hybrid Motor

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Originally Posted by 44'cruisingcat View Post
But, but..... then your 2:1 or 3:1 or 5:1 power equivalence goes out the window!

And while the electric faithful keep carping on about the continuous power capabilities of diesels, they seem to ignore the fact that most electric installations size a generator that doesnt come close to allowing continuous 100% throttle on the electric motors.
We're not ignoring anything of the sort. You've done a survey on this of EP owners have you? Tell us, how many were in your survey? How many data points do you have? I think we all know the answer to that.....

FYI, from someone who HAS done some research on a couple of dozen ( at least) EP users, I can tell you it's common to have a DC genset that is about half the total kW capacity of the motors, my case included. For our OV Servoprop ( 2 x 15kW) installation we have an Eniquest 16kW DC genset with continuous output to the propulsion bank of 15kW. That let's me run one motor at WOT on the genset, or more commonly, 7.5kW to each of the 15kW motors.

The reason for that is because that is all that is needed. If you need full WOT from both motors, that is an application for running both the genset and drawing from the propulsion bank. How long you want to do that for depends on what capacity your propulsion bank is. In my case we have a propulsion bank of 24.5kWh, so we can run WOT for about 50 minutes. Actually it is more than that because the genset is contributing while the motors are running.

You will notice, (won't you?) that that is longer than you're supposed to run your beloved double sized, 25% efficient, diesel at WOT.

And that is the point. Electric motors are capable of doing more work for longer than equivalently "sized" diesels, as has been laid out upthread in post #1467 by bridaus.

Please read svReality's post #1430 again. Ov 15kW compared to Yanmar 40kW diesels. Very similar results. On a Leopard 46, not a "rocketship".
Cruising on genset at 7 knots using 7kW.

Note this was not using your picked example of a Yanmar 2YM20 15kW, but a 54HP 40.5kW Yanmar. Are you saying Leopard would suggest putting a pair of 20HP diesels in their 46 foot cats??

As you're so fond of saying... "Are you serious?"
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Old 10-12-2018, 16:20   #1488
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
We're not ignoring anything of the sort. You've done a survey on this of EP owners have you? Tell us, how many were in your survey? How many data points do you have? I think we all know the answer to that.....

FYI, from someone who HAS done some research on a couple of dozen ( at least) EP users, I can tell you it's common to have a DC genset that is about half the total kW capacity of the motors, my case included. For our OV Servoprop ( 2 x 15kW) installation we have an Eniquest 16kW DC genset with continuous output to the propulsion bank of 15kW. That let's me run one motor at WOT on the genset, or more commonly, 7.5kW to each of the 15kW motors.

The reason for that is because that is all that is needed. If you need full WOT from both motors, that is an application for running both the genset and drawing from the propulsion bank. How long you want to do that for depends on what capacity your propulsion bank is. In my case we have a propulsion bank of 24.5kWh, so we can run WOT for about 50 minutes. Actually it is more than that because the genset is contributing while the motors are running.

You will notice, (won't you?) that that is longer than you're supposed to run your beloved double sized, 25% efficient, diesel at WOT.

And that is the point. Electric motors are capable of doing more work for longer than equivalently "sized" diesels, as has been laid out upthread in post #1467 by bridaus.

Please read svReality's post #1430 again. Ov 15kW compared to Yanmar 40kW diesels. Very similar results. On a Leopard 46, not a "rocketship".
Cruising on genset at 7 knots using 7kW.

Note this was not using your picked example of a Yanmar 2YM20 15kW, but a 54HP 40.5kW Yanmar. Are you saying Leopard would suggest putting a pair of 20HP diesels in their 46 foot cats??

As you're so fond of saying... "Are you serious?"
Thanks for backing up exactly what I said! So you cant run your electric motors at more than 50% power for any length of time without flattening your batteries.

I'd say that's even more restrictive than diesels continuous power capabilities.

I'd suggest that YOU read sv Reality's post again.

He stated that his OV 15s FLAT OUT matched his Yanmars AT 2800 RPM. NOT, repeat NOT at full throttle, but at reduced throttle.

As has been stated before without measuring fuel flow it's difficult to state for certain how much power was being made at 2800 rpm, because a dynamometer graph shows power vs rpm at FULL throttle, not part throttle.
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Old 10-12-2018, 16:37   #1489
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by bridaus View Post
PS: I'd skip the inverter and use a DC generator. Puts little/no load on the batteries when close to power needed at desired cruising speed and removes a source of inefficiency.
You'll still need an inverter for each motor, which I think is what transmitterdan was stating. There is no way you'd want brushes. Both DC brushless and induction (AC) motors use inverters, although the DC Brushless motor's inverter is often called a "controller". (both inverter types can be easily >95% efficiency)
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Old 10-12-2018, 17:27   #1490
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Re: Oceanvolt Hybrid Motor

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Originally Posted by OldMan View Post
Plus, if you have to run ICE to produce the power for EP, I contend you are less efficient that ICE direct drive.
I've heard this before, but while there's figures out there for better consumption from electric (some in this thread), I've never seen anything the other way showing better efficiency for ICE vs a electric motor + AC/DC gen (I'll ignore the batteries except as a way of flattening the electrical usage of the motors over waves etc.).

Can you produce anything to backup your contention?

BTW, for "efficiency" I'm talking actual not theoretical. I don't actually care how much the drivetrain takes or the electrical inversion or ... Because I'm writing this, I can decide to use a narrow version of efficiency as "fossil fuel consumed to go an equivalent cruising speed in similar reasonably benign conditions". This isn't about WOT/sprint speed in the middle of a cyclone .
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Old 10-12-2018, 17:46   #1491
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by BigBeakie View Post
We're not ignoring anything of the sort. You've done a survey on this of EP owners have you? Tell us, how many were in your survey? How many data points do you have? I think we all know the answer to that.....

FYI, from someone who HAS done some research on a couple of dozen ( at least) EP users, I can tell you it's common to have a DC genset that is about half the total kW capacity of the motors, my case included. For our OV Servoprop ( 2 x 15kW) installation we have an Eniquest 16kW DC genset with continuous output to the propulsion bank of 15kW. That let's me run one motor at WOT on the genset, or more commonly, 7.5kW to each of the 15kW motors.

The reason for that is because that is all that is needed. If you need full WOT from both motors, that is an application for running both the genset and drawing from the propulsion bank. How long you want to do that for depends on what capacity your propulsion bank is. In my case we have a propulsion bank of 24.5kWh, so we can run WOT for about 50 minutes. Actually it is more than that because the genset is contributing while the motors are running.

You will notice, (won't you?) that that is longer than you're supposed to run your beloved double sized, 25% efficient, diesel at WOT.

Like efficiency as your Eniquest 16kW DC genset with continuous output to the propulsion bank of 15kW. In fact, direct drive ICE is more efficient than the system you describe. The ICE on your genset must produce more than 15KW in order for the alternator to produce 15KW continuous (10% more ????).

FWIW, WOT rating on Yanmars is 1 hour. Not sure where the infatuation with WOT comes from, it's a ludicrous argument as nobody does such, but to carry it out. Run your Yanmar 1 hour at WOT, slow down for 1 hour at continuous rated rpm (88% power), then you can go another hour at WOT. In comparison, once your batteries are down, they'll stay down until cruising is over as all your power is going to the EP, nothing left to charge batteries.

Quote:
Originally Posted by BigBeakie View Post
And that is the point. Electric motors are capable of doing more work for longer than equivalently "sized" diesels, as has been laid out upthread in post #1467 by bridaus.

Please read svReality's post #1430 again. Ov 15kW compared to Yanmar 40kW diesels. Very similar results. On a Leopard 46, not a "rocketship".
Cruising on genset at 7 knots using 7kW.

Note this was not using your picked example of a Yanmar 2YM20 15kW, but a 54HP 40.5kW Yanmar. Are you saying Leopard would suggest putting a pair of 20HP diesels in their 46 foot cats??

As you're so fond of saying... "Are you serious?"
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Old 10-12-2018, 19:35   #1492
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by bluenomads View Post
I've heard this before, but while there's figures out there for better consumption from electric (some in this thread), I've never seen anything the other way showing better efficiency for ICE vs a electric motor + AC/DC gen (I'll ignore the batteries except as a way of flattening the electrical usage of the motors over waves etc.).

Can you produce anything to backup your contention?

BTW, for "efficiency" I'm talking actual not theoretical. I don't actually care how much the drivetrain takes or the electrical inversion or ... Because I'm writing this, I can decide to use a narrow version of efficiency as "fossil fuel consumed to go an equivalent cruising speed in similar reasonably benign conditions". This isn't about WOT/sprint speed in the middle of a cyclone .

Where does the heat that the electric end of a genset creates come from? A good size alternator/generator will easily produce 1KW of heat, hence the connected ICE must produce 1KW more than the output of the genset. Example: ICE puts out 16KW so genset can produce 15KW.



Simple engineering.
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Old 10-12-2018, 21:15   #1493
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by OldMan View Post
Where does the heat that the electric end of a genset creates come from? A good size alternator/generator will easily produce 1KW of heat, hence the connected ICE must produce 1KW more than the output of the genset. Example: ICE puts out 16KW so genset can produce 15KW.

Simple engineering.
Excellent. That is, unfortunately, rather what I expected.
Thank you mods for the ignore list!
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Old 10-12-2018, 23:57   #1494
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Re: Oceanvolt Hybrid Motor

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Originally Posted by tp12 View Post
If I may offer a suggestion, it may help the conversation here to have a set of working assumptions that you copy and paste into each post so everyone understands the context the comments are made within.

Then the focus can be on the actual discussion and not a lot of clarifying and back forth.

Maybe even state, roughly, a couple of real systems to compare or use as a starting point?
How can you claim magic electric HP if you provide clear definitions?

Of course, if it was just a question of electric motors typically being rated at a higher continuous HP and you can simply over current them to generate more than the rated HP, it's pretty simple and completely legal and defendable to provide a rating per the ICE HP methods (with appropriate documentation of course)....oddly, they never do that...

Maybe because if they did the results would make it obvious the argument doesn't work.
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Old 11-12-2018, 00:05   #1495
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Re: Oceanvolt Hybrid Motor

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Originally Posted by valhalla360 View Post
How can you claim magic electric HP if you provide clear definitions?

Of course, if it was just a question of electric motors typically being rated at a higher continuous HP and you can simply over current them to generate more than the rated HP, it's pretty simple and completely legal and defendable to provide a rating per the ICE HP methods (with appropriate documentation of course)....oddly, they never do that...

Maybe because if they did the results would make it obvious the argument doesn't work.


I have no dog in this fight. I'm trying to learn and see what is realistically feasible and it's often difficult to do in this thread. I watch it closely and I see people talking across each other and just wanted to offer an idea that I think would solve that and progress the discussion. Ultimately, that's what I'm interested in.
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Old 11-12-2018, 00:15   #1496
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Re: Oceanvolt Hybrid Motor

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Originally Posted by tp12 View Post


I have no dog in this fight. I'm trying to learn and see what is realistically feasible and it's often difficult to do in this thread. I watch it closely and I see people talking across each other and just wanted to offer an idea that I think would solve that and progress the discussion. Ultimately, that's what I'm interested in.
It's a long and convoluted thread but if you dig back in the old comments, this was laid out by several people including me way back.

While there is some validity to the "continuous duty cycle" argument, if you accept the lesser performance of 15kw for a particular boat and particular performance expectations...no you don't need a 75kw diesel to achieve the same and to compare to such is pure marketing flim-flam.

If you really have these lower expectations, you could also downsize the diesels similarly...say 17-20kw engines.

...but if you lay out the performance expectations, most designers are going to want an emergency capability...where you firewall the throttles in bad conditions for a reasonable period...now you run into two issue...how do you store that much power and if the motors are already at 100% doing 70% of hull speed, how do you get 200% out of them without them burning out in seconds?

If it was just a matter of different rating systems, the EV proponents would have been all over it from the start and laid out the use cases and how they handle those use cases without resort to magic HP equivalents. If they really are able to match a diesel of 2-3 times the HP, they could provide the calculations to prove it.
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Old 11-12-2018, 00:40   #1497
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by valhalla360 View Post
It's a long and convoluted thread but if you dig back in the old comments, this was laid out by several people including me way back.

While there is some validity to the "continuous duty cycle" argument, if you accept the lesser performance of 15kw for a particular boat and particular performance expectations...no you don't need a 75kw diesel to achieve the same and to compare to such is pure marketing flim-flam.

If you really have these lower expectations, you could also downsize the diesels similarly...say 17-20kw engines.

...but if you lay out the performance expectations, most designers are going to want an emergency capability...where you firewall the throttles in bad conditions for a reasonable period...now you run into two issue...how do you store that much power and if the motors are already at 100% doing 70% of hull speed, how do you get 200% out of them without them burning out in seconds?

If it was just a matter of different rating systems, the EV proponents would have been all over it from the start and laid out the use cases and how they handle those use cases without resort to magic HP equivalents. If they really are able to match a diesel of 2-3 times the HP, they could provide the calculations to prove it.
I've been here since the beginning. In fact, I've reread the thread a few times to try and make sure I understand what I'm reading. It's not my area of expertise.

I'd rather you try and sway the people with the EP knowledge and experience than me, because I'm not in a position to counter anything. Please don't think I'm suggesting you're not positively contributing to the thread, you are, but it's for others to answer your questions.
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Old 11-12-2018, 01:38   #1498
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by tp12 View Post


I have no dog in this fight. I'm trying to learn and see what is realistically feasible and it's often difficult to do in this thread. I watch it closely and I see people talking across each other and just wanted to offer an idea that I think would solve that and progress the discussion. Ultimately, that's what I'm interested in.
It's certainly feasible to have a hybrid propulsion system that works on a cruising boat.

You just have to be realistic about your goals.

If it's independence from fossil fuels, it's possible, but would require serious compromises, and arguably compromise on safety too.(The Pardys did without any engine at all. However they had a boat small enough to be rowed or towed by a rower, and enough celebrity that offers of tows were often available.)

If the idea is to save money by using less fuel, it's not realistic. Not at current prices.

Still the best way to save fuel is to optimize your boat for sailing.
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Old 11-12-2018, 05:04   #1499
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Re: Oceanvolt Hybrid Motor

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Originally Posted by valhalla360 View Post
If you really have these lower expectations, you could also downsize the diesels similarly...say 17-20kw engines.
No you cannot, the engines will die during warranty, but they will not be fixed under warranty.
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Old 11-12-2018, 05:14   #1500
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Re: Oceanvolt Hybrid Motor

RE: Yanmars, I don't believe "continuous" means the same to their marketing folks as it does to consumers and engineers. Sources (read for yourself).

https://www.sbmar.com/articles/conti...t-perspective/

https://www.boatdesign.net/threads/e...ratings.51333/

Quote:
Seems Yanmar will rate an engine at, say, “maximum output is 480 HP at 3300 RPM” and on the next line say that the same engine has a “continuous output at the crankshaft” of 436 HP at 3198 RPM (about 70 hp per liter). What that actually defines has left me befuddled for about 20 years. I truly have no real clue as to what Yanmar actually means by that, and I’ve been a dealer for the product (over 10 years).

Quote:
There is a reason that warranty documents feature pages of really fine print and loads of exemptions. It is really important when choosing an engine that you actually read the warranty and how certain use is exempt (as in hours per year, commercial / recreational, maintenance documentation, and total hours)

Some brands (Volvo Penta, Yanmar) tend to focus on recreational users with their ratings (nothing wrong with that). Some offer multiple ratings with virtually every engine (for example, some Cummins engines have 10 or more ratings, as do many CAT engines).

There is a bit of marketing and PR involved. We are regulated as to the accuracy of the rating (in our case, by the EU, NATO, and ISO standards, not to mention classification), but how that rating is portrayed in sales is a really gray area, as in there are no set standards or regulations...The curves and specifications must be accurate, but that is all.
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