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Old 12-12-2018, 08:25   #1561
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Oceanvolt Hybrid Motor

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Originally Posted by bridaus View Post
In fact it does not. Only the electric motor (and controller + batteries) see the load. The ICE generator puts excess capacity into batteries, and doesn't care about excess load. It is sized and designed to be at optimal load at all times.


That sounds good, but itís not what happens, unless the charger is at its max output, charger or generator itself.
If itís not at its max output, then the load is passed through the battery bank to the generator.
Just like when we are washing clothes, when the water pump kicks in, the little Honda speeds up cause of the increased load on the battery bank.
Of course if my charger was maxed out, it canít pick up any more load, and then of course it comes from the bank, either in reduced charge current, or if the load is big enough, it sucks down the the output and then draws from the bank too.

From just a pure sustained motoring perspective, a hybrid electric system isnít going to be efficient, however if you donít plan on extended motoring, well then in my opinion your in the realm of a hybrid electric drive.

If you look at the Brake Specific Fuel consumption curves in any Yanmar manual, you will find that there is a sweet spot of RPM that is most efficient, unfortunately itís not much difference, it exists, just itís not a big difference.
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Old 12-12-2018, 08:31   #1562
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Re: Oceanvolt Hybrid Motor

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That sounds good, but itís not what happens, unless the charger is at its max output, charger or generator itself.
If itís not at its max output, then the load is passed through the battery bank to the generator.
Just like when we are washing clothes, when the water pump kicks in, the little Honda speeds up cause of the increased load on the battery bank.
Of course if my charger was maxed out, it canít pick up any more load, and then of course it comes from the bank, either in reduced charge current, or if the load is big enough, it sucks down the the output and then draws from the bank too.
Little Honda's (AC generators) are not what we are talking about in this thread, we are talking about DC generators specifically designed for propulsion.
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Old 12-12-2018, 08:34   #1563
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Re: Oceanvolt Hybrid Motor

Back in the 1070ís the Russians built a City bus that had a small diesel running a generator to charge a battery bank, and it had regenerative braking.
Idea was that a City bus spends most of its time sitting waiting for people to load and unload, then needs the BIG motor to accelerate int traffic where it then maintains speed for a short time, then slows of course and sits again.
It worked, and worked well, a little something like a 5 KW generator ran the City bus easily, and did substantially decrease fuel consumption.

Unfortunately it wasnít successful because it couldnít sustain high speeds for long at all, and I guess maybe busses need to be repositioned etc at times and need the ability to jump on the highway?
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Old 12-12-2018, 08:36   #1564
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Re: Oceanvolt Hybrid Motor

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The problem with the direct drive system sized for max power is that at that speed the propeller can only absorb about twenty percent of what the engine can generate, so the governor throttles it back to hold rpm and that drops you back to the less efficient part of the bsfc map. I posted a map from a modern small diesel in the previous post.
No.
That's a problem specific to a fixed-pitch prop load.
The OV system uses a variable-pitched prop.
Why do you insist on comparing apples and bananas?
Did you read that Dockhead runs variable-pitched on his direct drive?
Your comparison is false, and only adds to the smoke and mirrors perception.

You cannot break Newton's laws. The only hope for your argument (and to stay within Newton's 2nd law) is that the comparable direct-drive diesel system would have to be very inefficient or simply the wrong size. So far, you (and others) are conveniently picking a direct-drive system that is NOT comparable. That's fine for message board color, but I think it harms the EP cause overall.

Many of us diesel direct folks would like to switch, but this is still early-days. The technology has improved quite a bit in even the two years this thread has been going. Great. We're getting there. Why do some feel the need to stretch the truth?

The OV adopters have posted a few real-world numbers here. Good on them for sharing. I'm personally cheering them on. We're all eagerly waiting to see more, like performance into heavy seas and long-term fuel usage. That's what makes this forum great, as it is independent of the manufacturer in question. None of those early-adopters benefits from somebody making false comparisons, however.
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Old 12-12-2018, 09:01   #1565
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Re: Oceanvolt Hybrid Motor

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If by continuously you mean for 30 minutes every 8 hours, then sure. Continuously. I guess words don't matter anymore. Please read the manual.

You'll be using so much fuel that you won't notice your engine melting anyway. Check the fuel consumption for that engine at that HP/RPM. Good luck.

FWIW, the continuous rating on my engine is DIN6270a. I'll let you learn about what that means.
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Old 12-12-2018, 09:07   #1566
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Re: Oceanvolt Hybrid Motor

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Let me do the math for the engine being off. Zero, times zero, carry the one..... I believe that comes out to zero fuel consumption. It probably sounds a bit like sailing.

Before someone yells at us for claiming "magic" zero fuel consumption, we know that we have to turn the generator back on at some point depending on how much we are pulling from the batteries based on how fast we are going, but it all contributes in the end to some amount of fuel burn. If we can do it efficiently while burning it, and zero while off, the sum in theory should be more efficient. I believe current properly designed systems can achieve this now, but I'm also interested in the real numbers. I'm skeptical of all claims until I have reproducible data.

Edit: The one thing for sure, there are a lot of smart people betting their livelihood on this. They may be wrong, but there is something causing them to bet big. It's not smoke and mirrors when engineers are involved.

A properly designed ICE direct drive will always be more efficient at long range cruising than using ICE/EP including cycling power in/out of batteries.



I'm a fan of hybrid, I'm not betting against it. I own a 2 motor (non-plugin) hybrid car, different application, more reasonable expectations.



It's the outlandish claims being propagated that are bothersome.



If hybrid EP would deliver like power for like cost (capex and opex), it would be the end of ICE direct drive. But it doesn't, so the EP companies are spending enormous amounts of engineering and marketing (including BS) to build a market. I appreciate those paying the extra cost now, so I can take advantage of the technology when it commoditizes to reasonable pricing.
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Old 12-12-2018, 09:22   #1567
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Re: Oceanvolt Hybrid Motor

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Originally Posted by cyan View Post
No.
That's a problem specific to a fixed-pitch prop load.
The OV system uses a variable-pitched prop.
Why do you insist on comparing apples and bananas?
Did you read that Dockhead runs variable-pitched on his direct drive?
Your comparison is false, and only adds to the smoke and mirrors perception.

You cannot break Newton's laws. The only hope for your argument (and to stay within Newton's 2nd law) is that the comparable direct-drive diesel system would have to be very inefficient or simply the wrong size. So far, you (and others) are conveniently picking a direct-drive system that is NOT comparable. That's fine for message board color, but I think it harms the EP cause overall.

Many of us diesel direct folks would like to switch, but this is still early-days. The technology has improved quite a bit in even the two years this thread has been going. Great. We're getting there. Why do some feel the need to stretch the truth?

The OV adopters have posted a few real-world numbers here. Good on them for sharing. I'm personally cheering them on. We're all eagerly waiting to see more, like performance into heavy seas and long-term fuel usage. That's what makes this forum great, as it is independent of the manufacturer in question. None of those early-adopters benefits from somebody making false comparisons, however.
Why do you insist that a couple of bananas in an apple orchard should invalidate the discussion about apples?

Yes, you're correct that it's a problem specific to single speed fixed pitch cases. Yes, one vendor makes a single model of electric drive with a variable pitch propeller. And yes, you managed to find and quote the only post here where I didn't use the words single speed and fixed pitch but adopted another poster's shorthand instead. Congratulations.

Given that the posts above it all used the single speed and fixed pitch language, I don't think I was creating any confusion. And given that virtually all modern sailing catamarans are equipped with single speed fixed pitch systems, diesel or electric, I do think it is the appropriate comparison to make. I've looked at option sheets for a dozen or so models of catamarans from several makes, and while several offered folding propellers, not one offered variable pitch.
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Old 12-12-2018, 09:32   #1568
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Re: Oceanvolt Hybrid Motor

We should probably not talk variable pitch, that confuses the situation more. Both can use it, both can benefit but it adds a layer of complexity I don't think we want to try to address. I used to have the math skills for it, but not so much anymore. If someone here is an engineer that works with props, open to the real math, but otherwise we should stick to fixed pitch for our apples to apples comparison.
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Old 12-12-2018, 09:34   #1569
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Oceanvolt Hybrid Motor

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Originally Posted by bridaus View Post
Little Honda's (AC generators) are not what we are talking about in this thread, we are talking about DC generators specifically designed for propulsion.


Source of the power is irrelevant, power will be passed through the bank as long as there is excess capacity of the charge source regardless of what it is.
If there is no excess capacity then of course power will be drawn from the bank decreasing its state of charge.

Dockhead and I both use an Autoprop, which is a self pitching prop.
It works and works well, but likely isnít as efficient as a controllable pitch prop would be, although we are likely talking small efficiency gains here, itís not much different.
For example, what is an inefficient prop is the majority of the feathering props as they donít have an airfoil and blade twist, just simply flat plates
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Old 12-12-2018, 09:34   #1570
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Re: Oceanvolt Hybrid Motor

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A properly designed ICE direct drive will always be more efficient at long range cruising than using ICE/EP including cycling power in/out of batteries.
Saying this doesn't make it true. Please make your case with numbers.
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Old 12-12-2018, 10:14   #1571
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Re: Oceanvolt Hybrid Motor

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Source of the power is irrelevant, power will be passed through the bank as long as there is excess capacity of the charge source regardless of what it is.
If there is no excess capacity then of course power will be drawn from the bank decreasing its state of charge.
And if the power is equal to the load, there will be no power in or out of batteries.
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Old 12-12-2018, 10:18   #1572
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Re: Oceanvolt Hybrid Motor

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FWIW, the continuous rating on my engine is DIN6270a. I'll let you learn about what that means.
That's how they calculate the ratings, not what it's rating is. What engine do you have? That would give me a better head start. You're my first taker on the "what is my duty rating" challenge. BTW, some mfg's/sales try to hide this stuff, so if your engine is of a certain age, there will be nothing but a guy or manual somewhere on a shelf that knows and no one else. You might have that manual, you might not.
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Old 12-12-2018, 10:30   #1573
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Re: Oceanvolt Hybrid Motor

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Saying this doesn't make it true. Please make your case with numbers.

I've already shown you 11% loss for 15KW ICE/EP hybrid, now you are adding the loss associated with charging/discharging batteries. You are up to at least 15% loss when using battery juice. That's a big hill to climb to match properly engineered direct drive.


The use case is long hours at cruising speed because that is where the most fuel is burnt.



Example:


Honda's 2-motor hybrid in their cars. They use an Atkinson duty cycle ICE and electric motor. Below 45mph, pure EP, ICE/regen producing electricity, small battery bank, EP driving the wheels. Above 45mph, depending on load, they will switch to a single gear direct drive and engage the ICE to the drivetrain. If hybrid was so efficient, why would they even use the single gear and associated complexity? Afterall, the ICE they use is the most efficient design there is! Because it's more efficient to drive the wheels with the ICE directly connected at cruising loads than via the hybrid EP. There is no difference on a boat!
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Old 12-12-2018, 10:45   #1574
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Re: Oceanvolt Hybrid Motor

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I've already shown you 11% loss for 15KW ICE/EP hybrid, now you are adding the loss associated with charging/discharging batteries. You are up to at least 15% loss when using battery juice. That's a big hill to climb to match properly engineered direct drive.

The use case is long hours at cruising speed because that is where the most fuel is burnt.

Example:

Honda's 2-motor hybrid in their cars. They use an Atkinson duty cycle ICE and electric motor. Below 45mph, pure EP, ICE/regen producing electricity, small battery bank, EP driving the wheels. Above 45mph, depending on load, they will switch to a single gear direct drive and engage the ICE to the drivetrain. If hybrid was so efficient, why would they even use the single gear and associated complexity? Afterall, the ICE they use is the most efficient design there is! Because it's more efficient to drive the wheels with the ICE directly connected at cruising loads than via the hybrid EP. There is no difference on a boat!
I don't see data for your 11%, I could be missing the post, this thread is large.

RE: 15% battery loss, also no data found. When cruising at planned cruise given input power, battery loss is effectively zero. Even if our power needs are off a little bit, loss still very small with slow rate of charge/discharge. Pushing lots of current in or out of bank (really only when exceeding generator power by a lot) there is a definite effect, but now battery chemistry and charge rates/bank sizes/etc. have to be discussed. Are we ready for that yet? No one has answered me on how to calculate the amount of reserve power needed, so I'm not sure we're ready.

Just on sfc alone there's a possibility (depending on engine/etc.) of 30%. I don't have enough data to put this all together yet, but just with that one number I think EP could be more efficient. If done right. Who knows if OV, Elco, others have done it right yet, but I think so there are happy customers.

PS: I think we already discussed that car applications don't apply here. Who knows why Honda did it that way, those cars aren't selling all that well either, wonder why that is?
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Old 12-12-2018, 10:53   #1575
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Re: Oceanvolt Hybrid Motor

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The use case is long hours at cruising speed because that is where the most fuel is burnt.
Well that is exactly where EP stops making sense!

But there are those sailing, not on schedules, that plan to only use power for very short periods. If the case can be made that EP is practical / cost-effective at least for them, even for a heavy monohull, there's an entry point anyway.
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