Oceanvolt Hybrid Motor

[OldMan]

Originally Posted by john61ct

Perhaps you think that some too idealistically believe such a power source would be sufficient for "normal" usage patterns of propulsion energy?

Others believe regen is 'a game changer'.

Originally Posted by john61ct

I agree that is not realistic, we're not saying this is amazingly revolutionary; the use case for me is House loads, maybe contributing to reducing some small % of overall ("normal" level of) fossil fuel costs, on a similar sort of scale to solar and wind inputs.

I agree, but solar/wind work both moored and underway whereas regen has a very narrow window of opportunity to add value. Regen is not useful moored, sailing in light winds, or while motoring.


If you have enough solar to cover house loads, what does regen add?

Originally Posted by john61ct

But within that context, incrementally compared to existing real-world demonstrations, I'm pretty sure this is genuinely impressive?

It's impressive, just trying to understand the value prop.

[john61ct]

Yes, time spent sailing at relatively high speed is the determining / limiting factor for regen's contribution.

[Dockhead]

Originally Posted by john61ct

. . .the use case for me is House loads, maybe contributing to reducing some small % of overall ("normal" level of) fossil fuel costs, on a similar sort of scale to solar and wind inputs.. .

Better than reducing fuel use, which could probably never be recouped by the cost of such an installation -- power source on multiday sailing passages.


I really needed that last summer -- 4000 miles from the South Coast of England to Northern Greenland and back in one summer. We had some fantastic passages under sail, days on end at 8, 9 and 10 knots, and running out of battery power was a MAJOR BUZZ KILL -- reduce sail to get heel off, run the generator or put on the main engine which was not needed for propulsion -- bleh!! I would have given a lot to have had another way to produce power.


The redundancy of such a system would also be valuable.



A controllable pitch propeller and a way to disengage the shaft would probably be needed to make this work really well.

[OldMan]

At some point, it all comes down to cost.

This is an attempt to try and look at costs of OV hybrid EP vs direct drive diesel. It's only a quick cursory look using pricing gathered from quick searches on the Internet. Someone with better knowledge feel free to jump in. This doesn't go as deep as installation and is missing some items.

Use case would be a catamaran, 40-45'.

Hybrid EP

Oceanvolt Pricing (from OV website):
https://oceanvolt.com/price-examples/

(2) SD15, 28kWh batteries = 68,715.00 euro or $79,055.00 USD

"The prices are examples and exclude VAT and shipping.
The system prices include: motor(s), lithium batteries, propeller(s), charger(s), system monitoring, standard warranty & system certification. Liquid cooling is included in all systems above 10kW.
System prices do not include installation or the system, generators or solar panels and their accessories."

Generator

20 kW DC Generator - Trans Marine Pro - Renewable Energy Specalists
Polar Power 13-20kW DC Generator 8340VP-40 $21,494.15 USD

Total Hybrid EP = $100,549.00 USD

Direct Drive Diesel

https://www.barrus.co.uk/media/2956/...-list-2017.pdf

3ym30AC (22.1kw, 20.1kw continuous) with SD25 sail drive = BP6739.00 $8598 USD = $17,196.00

460AH @ 12V Trojan Trillium (5) @ $1000 = $5000.00
120A charger = $1200

Northern Lights Marine Generator M673L3 6KW generator = $13,295.00

Total Direct Drive Diesel = $36,691.00 USD

A $64.5k USD upcharge (2.7 times) for Hybrid EP. If anywhere close to accurate, it'll take a long time for EP to make a dent in the direct drive market.

[transmitterdan]

That's correct and they can never make up the price gap by increasing volume. These EP systems are simply marinized versions of components that have been in production for 20 years or more. The DC genset may not be produced in volume but it isn't dominating the price gap either. If it were free there would still be a huge cost gap. Unless OV is making ridiculous profits (most likely not) then EP has a real economic issue. How much more $/€/£/¥ people are willing to pay to burn more fuel will decide that I guess. I'm not optimistic about EP's future in cruising as readers already know. Remember that great philosopher James Carville: it's the economy...stupid...

[OldMan]

Originally Posted by transmitterdan

That's correct and they can never make up the price gap by increasing volume. These EP systems are simply marinized versions of components that have been in production for 20 years or more. The DC genset may not be produced in volume but it isn't dominating the price gap either. If it were free there would still be a huge cost gap. Unless OV is making ridiculous profits (most likely not) then EP has a real economic issue. How much more $/€/£/¥ people are willing to pay to burn more fuel will decide that I guess. I'm not optimistic about EP's future in cruising as readers already know. Remember that great philosopher James Carville: it's the economy...stupid...

I came into this discussion objectively, wanting to figure it out, but an engineer with a business degree is somewhat dangerous for snake oil salesmanship.


The largest percentage of fuel burn by far on a cruising sailboat is long range motoring, and I'm now convinced hybrid EP will burn at least 10% more fuel compared to diesel direct drive. A physicist friend told me, the more gobbledygook you put between the ICE and prop, the less efficient the system.



Moving around a marina or moving from mooring to 'sails up' is the only area where EP can save diesel, but that's such a small part (<1-2%) of a diesel budget on a cruising sailboat, it's so small it doesn't count.


I guess I don't 'get it'.

[john61ct]

I won't even consider that sort of money, but my interest comes from the desire to be able to produce high amps DC for freezing holding plates, charging LFP quickly and high gph watermaking.

I could do without powered propulsion and just row, but if I can install a little motor for not too much I will. 10hp outboard would be OK, but prefer to run off existing fuel. . .

No way I want two diesel engines.

[transmitterdan]

I don't understand the fascination with DC gensets. DC is more expensive to transport (bigger wires) unless it is 100V which no one can use. More expensive/lossy to convert to other voltages. DC gensets are really AC with internal or external rectifiers. The only advantage I can guess is they don't need constant speed ICE. But is that really an important advantage?

If one is going to consume power such that ICE is the only primary source why is a plain old reliable Northern Lights AC generator with sound proofing not optimal? All the big power consumers can run from it directly without wasteful converters. The wiring is much lighter. Even a modicum of maintenance (change belt, impeller, oil and antifreeze regularly) will mean a NL set could outlast the boat since there are no side load bearings. Big holding plates can store "cold" losslessly. Same goes for a big water tank, they store water losslessy too. So why the need for a huge battery bank? A small bank with inverter will power the computer and entertainment. LED lighting draws next to no power.

When on shore power everything works the same as when at sea which improves the cost/reliability equation. A Torqedo or small propane outboard will get most boats in or out of the slip if no plans for long distance motoring.

[Dockhead]

Originally Posted by transmitterdan

I don't understand the fascination with DC gensets. DC is more expensive to transport (bigger wires) unless it is 100V which no one can use. More expensive/lossy to convert to other voltages. DC gensets are really AC with internal or external rectifiers. The only advantage I can guess is they don't need constant speed ICE. But is that really an important advantage?. . .

Being able to vary the RPM with the load gives great advantages in efficiency (fuel burn), and more importantly, health of the generator at light loads. I like DC gensets, personally. AC gensets are particularly sensitive to light load damage because they stay at full working revs whatever the load. See for example all those gensets in the Caribbean with polished bores from air conditioning on cool nights.



DC generators are great at least for use cases which require a lot of variation of load. But an underpowered hybrid which will use its genset wide open all the time it's being used, won't see any big advantage from a DC generator.

[transmitterdan]

I would like to see some data on the difference in fuel consumption vs. load, AC vs. DC. Today’s engines are pretty efficient at varying loads even turning at constant speed. Also, life cycle cost will likely not favor the DC genset. And big Lithium based battery banks mean the DC genset runs at high load most of the time anyway.

How many commercial vessels use DC gensets? They would stand to gain financially by saving money so should be on the forefront.

[Dockhead]

Originally Posted by transmitterdan

I would like to see some data on the difference in fuel consumption vs. load, AC vs. DC. Today’s engines are pretty efficient at varying loads even turning at constant speed. Also, life cycle cost will likely not favor the DC genset. And big Lithium based battery banks mean the DC genset runs at high load most of the time anyway.

How many commercial vessels use DC gensets? They would stand to gain financially by saving money so should be on the forefront.

I think the big question is efficiency of the diesel engine. There was a huge discussion about this earlier in the thread. Diesel engines are most efficient at something like 80% of maximum load or so for that RPM -- you can gain up to 20% or so from operating them here versus at more or less load for the RPM. If you keep the engine at constant speed and you have varying loads, obviously you will be working the engine a lot at sub-optimal regimes. And what would be a healthy load at a lower RPM might be low enough to cause wet stacking if you keep the revs up.



DC genset allows you to vary the RPM, so optimize efficiency and avoid wet stacking conditions.



As to generator efficiency -- I don't know anything about this, and would be interested to learn about it. The efficiency figures we read are in optimum conditions, and it would be interesting to know what the real life range of efficiencies are.


As to DC vs AC -- AFAIK, AC is inherently more efficient because of one less stage of rectification. But I would like to learn more about it if someone cares to share.

[transmitterdan]

All rotating magnet generators produce AC. It is a mathematical result of the rotating magnets. DC generators have a set of internal (or external) rectifiers (or commutating rings in days of yore) to convert AC to DC. Likewise both types must have a source of magnetism which is usually in the form of an electro-magnet needing a power source to "excite" a magnetic field. Some small generators use permanent magnets for the excitation but that becomes impractical at multi-kilowatt powers. The main driver of efficiency is heating losses in the magnets and the wire. Lower frequency means lower magnetic losses. Higher voltage & lower current means lower wire losses. So overall losses aren't different because of AC or DC but because of the rotation speed and choice of output voltage. At 1-2kW output there are other losses that dominate so the above may not apply.

One can pretty easily make a 10kW DC generator more efficient than an AC by choosing higher voltage output. Choose 1,000V for DC and 240V for AC then the DC generator will likely be more efficient. But choose 12V for DC and 120V for AC and the AC unit will win. Also, choose 3 phase for the AC and it gets even more efficient. That's why nearly all DC alternators are already multi-phase inside. It's also why EP chooses a voltage higher than traditional DC voltage levels.

As to engine efficiency, modern diesels are pretty efficient throughout the RPM range. The question is whether the efficiency gained by using variable speed depending on load is significant. In either case (AC-DC) it is probably most efficient to pull 80% from the diesel all the time and have an efficient means of storing that energy for use later.

[john61ct]

For me, I just have little use for AC at all, the big consumers I listed power direct off DC.

[transmitterdan]

Originally Posted by john61ct

For me, I just have little use for AC at all, the big consumers I listed power direct off DC.

Actually they don’t. DC motors convert DC to AC in order to rotate. A DC motor without commutation (voltage reversal) would never rotate.

[ssmoot]

Originally Posted by transmitterdan

That's correct and they can never make up the price gap by increasing volume. These EP systems are simply marinized versions of components that have been in production for 20 years or more. The DC genset may not be produced in volume but it isn't dominating the price gap either. If it were free there would still be a huge cost gap. Unless OV is making ridiculous profits (most likely not) then EP has a real economic issue. How much more $/€/£/¥ people are willing to pay to burn more fuel will decide that I guess. I'm not optimistic about EP's future in cruising as readers already know. Remember that great philosopher James Carville: it's the economy...stupid...

You can buy motors with double the power of the OV units all day long for under $1,000/unit.

A 24kWh Leaf pack will run you about $4,500 in like-new "12 bar" (better than 92% of original rated capacity remaining) condition.

OV has to pay engineering and sales salaries in a niche of a niche market, and their customers are willing to pay what they ask for an installed, vendor supported solution. I think that's all the explanation needed for their pricing.