Oceanvolt Hybrid Motor

[SDChristian]

Originally Posted by OldMan

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'.

Not if you moor in a river!

[myocean]

Originally Posted by OldMan

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.

This is a quite basic statement. I suggest to read the attached article from Nigel Calder which is helping to understand the complexity of the topic. (but I think this does not look into catamaran hulls)

[transmitterdan]

Originally Posted by myocean

This is a quite basic statement. I suggest to read the attached article from Nigel Calder which is helping to understand the complexity of the topic. (but I think this does not look into catamaran hulls)

Thanks for posting those. I think Nigel has done a good job of trying (and failing) to find a way to get hybrid EP to be as efficient as mechanical drives. But he just couldn't do it and that is also ok. He correctly opines that the real benefit of hybrid is the abundant electrical power it can provide for non-propulsion lifestyles similar to shore side living. But that benefit can only come with burning diesel fuel. Which is also ok.

But those two articles should put to rest the idea that EP is way more efficient than mechanical. Read the last section of the second article which summarizes the current situation very accurately.

Hulls make no significant difference because it takes the same amount of propulsion thrust to make any given hull go whether that thrust comes from an ICE or electric motor. So there is no magic about multi-hulls that helps EP efficiency. If an EP system is much lighter than ICE it can help in the margins but it won't move the results significantly. And cruisers just stash more stuff if they can anyway...

[myocean]

Originally Posted by transmitterdan

Thanks for posting those. I think Nigel has done a good job of trying (and failing) to find a way to get hybrid EP to be as efficient as mechanical drives.

That is right! We need to take into account that power electronics has improved in the recent years - you may gain about 5% with this, so not a lot.
But batteries got a lot better! Today, a lithium battery will not waste more than 5% of the energy you put in and take out again. Nigel Calder calculates with 15% loss.
So, in the end the efficiency could may reach the same level but probably not more.

Originally Posted by transmitterdan

Hulls make no significant difference because it takes the same amount of propulsion thrust to make any given hull go whether that thrust comes from an ICE or electric motor.

This is logic, but misses the point. Because a major factor for hybrid-electric systems in sailboats is the hydrogeneration which allows to eliminate generator use in daily life. This is from where you can get the an over-all reduction of fuel consumption.
And here you gain a lot with a catamaran in comparison with a monohull:
You have a lower hull resistance which leads to more speed when sailing (=much! more energy into the battery). And you have two props available for hydrogeneration, not just one.
Then, when using the same harvested energy for motoring, you need less for the same speed (again due to the lower hull resistance).
So, in the end with a catamaran you get much more motoring time out of the same sailing time than with a monohull of the same length.
If you calculate this conservatively you end up with about 1 hour of motoring for every 6 hours of sailing with a proper boat. Performance cats can be better and the adjustable prop from Oceanvolt is even quite a bit better.

[OldMan]

Originally Posted by myocean

This is a quite basic statement. I suggest to read the attached article from Nigel Calder which is helping to understand the complexity of the topic. (but I think this does not look into catamaran hulls)

Yes, thanks for posting!

Originally Posted by myocean

That is right! We need to take into account that power electronics has improved in the recent years - you may gain about 5% with this, so not a lot.
But batteries got a lot better! Today, a lithium battery will not waste more than 5% of the energy you put in and take out again. Nigel Calder calculates with 15% loss.
So, in the end the efficiency could may reach the same level but probably not more.



This is logic, but misses the point. Because a major factor for hybrid-electric systems in sailboats is the hydrogeneration which allows to eliminate generator use in daily life. This is from where you can get the an over-all reduction of fuel consumption.
And here you gain a lot with a catamaran in comparison with a monohull:
You have a lower hull resistance which leads to more speed when sailing (=much! more energy into the battery). And you have two props available for hydrogeneration, not just one.
Then, when using the same harvested energy for motoring, you need less for the same speed (again due to the lower hull resistance).
So, in the end with a catamaran you get much more motoring time out of the same sailing time than with a monohull of the same length.
If you calculate this conservatively you end up with about 1 hour of motoring for every 6 hours of sailing with a proper boat. Performance cats can be better and the adjustable prop from Oceanvolt is even quite a bit better.

This use case saves ~4L of diesel a day (4KWh per liter in a direct drive diesel). That's $4 USD a day savings, assume 200 sailing days a year, $800/yr. How many years is the payback?

[Q Xopa]

Originally Posted by 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.

The current crop of Inverter 'suit case' generators, Honda EU220i etc are and example of DC generator style operation.
Ok this gets a bit murky with definitions because these are obviously AC output gens.

But for those of us that remember pre Inverter generators they where typically the cage mount 4-4.8kva units. That used to scream away at constant RPMs, load or no load.
Now they are largely replaced by 2kva Inverter units. Much, lighter, cheaper and fuel efficient. The fuel efficiency does depend largely on load profile, as Dockhead said. However it is rare that loads are optimum and constant enough to not make it mostly worthwhile.
They can get away with being smaller as they can be sized for average loads, not peak loads.

[myocean]

Originally Posted by OldMan

$4 USD a day savings, assume 200 sailing days a year, $800/yr. How many years is the payback?

I think for most of the fans this is not about payback times. An electric drive is luxury and will be for a couple of years from now on.
For many cruisers silence on board is the ultimate luxury.
Who hates diesel noise when motoring? I think most of us, right?
So, from my point of view the motivation to get such a system is arising from the desire to eliminate diesel noise and diesel emissions.

[OldMan]

Originally Posted by myocean

I think for most of the fans this is not about payback times. An electric drive is luxury and will be for a couple of years from now on.
For many cruisers silence on board is the ultimate luxury.
Who hates diesel noise when motoring? I think most of us, right?
So, from my point of view the motivation to get such a system is arising from the desire to eliminate diesel noise and diesel emissions.

Hopefully there is enough like you so that companies like OV can survive.

[john61ct]

Originally Posted by transmitterdan

Hulls make no significant difference because it takes the same amount of propulsion thrust to make any given hull go whether that thrust comes from an ICE or electric motor

Unless the primary goal of a bespoke design is to **make** low-diesel EP (appear to be) practical for PR or idealistic purposes.

At huge expense and compromises in both other areas of functionality (no schedules) and beauty as well I'm sure.

[saghost]

Originally Posted by 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.

A couple things to note about this comparison: the conventional solution while cheaper is much heavier and has ~20% of the battery capacity.

(Assuming I finally figured out what you meant and it's 460 Ah total by having 5 92 Ah Trillium batteries. I was struggling for a while to find a 460 Ah Trillium and thinking you were going for the same total capacity by having five of them.)

(All weights dry. Not going to try to go through the math for fluids today, but the conventional solution has more of them.)

3YM30AE + SD25: 157 kg - 2x = 314 kg

2x 65 Ah starter batteries at ~50 pounds each: 45 kg

M673L3 = 191 kg w/sound shield

I couldn't find a requirement for the generator starter battery; assume it's the same as the other two - 22.5 kg

5 Trillium 92 Ah @12.3 kg each = 61.5 kg

Total system weight 634 kg

Oceanvolt SD15 - 46 kg each, 92 kg total

Polar Power 8340VP-40 generator 180 kg

I didn't see any specs for this starter battery either, but it does appear to be intended to run a 12V electrical system and starter instead of using the 48V PM generator to start. Assume the same 65 Ah as the rest - 22.5 kG

I don't know exactly what pack Oceanvolt intended to supply, but the heavy end of the likely range would be 5x Torqueedo 48-5000 - $5200 each, 36.5 kg each - 182.5 kg total

Light end of the battery range - 6x tesla 85 modules:

https://www.evwest.com/catalog/produ...roducts_id=463

25 kg per, $1600 per. total 150 kg.

Oceanvolt system weight as described, 445-477 kg, depending on your assumptions about the pack.

Almost 200 kg lighter - 2/3rds the weight - even with the conventional system having a fancy lithium house pack that's 20% of the capacity (a lead acid house pack would have made this substantially bigger.)

The other thing to keep in mind is that Oceanvolt is a high-end - and high priced system integrator in the emerging electric drive market. The Tesla batteries with more capacity (32 kWh) are only $9.6k, and added to electric yacht's 20 kW saildrives at $13.5k each make a $37k system that's on paper more capable than OceanVolt's $79k:

https://www.bruceschwab.com/electric...ic-propulsion/

Of course, then you're playing system integrator and dealing with any reliability issues (the Tesla packs would also need an enclosure and BMS added.)

You'd presumably still want the generator in addition for motor-sailing situations, which would make the total something in the $60k range.

[transmitterdan]

Originally Posted by Q Xopa

The current crop of Inverter 'suit case' generators, Honda EU220i etc are and example of DC generator style operation.
Ok this gets a bit murky with definitions because these are obviously AC output gens.

I think you missed the point. There is simply no such thing as a rotating DC generator. A rotating magnet cannot produce DC (at least not for long). So DC generators produce AC then rectify it.

The Honda people haven’t escaped the laws of physics. The EU2000 creates AC then rectifies it to DC then inverts it back to AC but with regulated voltage and frequency. The advantage is the gasoline motor doesn’t have to run constant speed. So not too different than what a boat EP system does with a so-called DC generator. They add a battery in the middle which increases the losses a little.

All these rectification and inverter steps create losses. Getting 90% efficiency at each of these steps is pretty good performance. So about 81% efficiency in the electrical stuff at full power is decent. I think Nigel said he measures something like that.

[transmitterdan]

Originally Posted by myocean

I think for most of the fans this is not about payback times. An electric drive is luxury and will be for a couple of years from now on.

For many cruisers silence on board is the ultimate luxury.

Who hates diesel noise when motoring? I think most of us, right?

So, from my point of view the motivation to get such a system is arising from the desire to eliminate diesel noise and diesel emissions.

Yep, that’s the desire but not the reality. You simply cannot motor for 8-12 hours on any EP system without a diesel generator. And it will likely take 24 hours hard sailing for the regen system to produce enough juice for 2-4 hours of silent motoring. Less if you run all those appliances like aircon, fridge, freezer, water maker, etc.

Everyone wants the same thing you want, inexpensive to purchase, zero cost to operate with no noise or smell. The laws of physics say you can’t have it.

[OldMan]

Originally Posted by saghost

A couple things to note about this comparison: the conventional solution while cheaper is much heavier and has ~20% of the battery capacity.

(Assuming I finally figured out what you meant and it's 460 Ah total by having 5 92 Ah Trillium batteries. I was struggling for a while to find a 460 Ah Trillium and thinking you were going for the same total capacity by having five of them.)

(All weights dry. Not going to try to go through the math for fluids today, but the conventional solution has more of them.)

3YM30AE + SD25: 157 kg - 2x = 314 kg

2x 65 Ah starter batteries at ~50 pounds each: 45 kg

M673L3 = 191 kg w/sound shield

I couldn't find a requirement for the generator starter battery; assume it's the same as the other two - 22.5 kg

5 Trillium 92 Ah @12.3 kg each = 61.5 kg

Total system weight 634 kg

Oceanvolt SD15 - 46 kg each, 92 kg total

Polar Power 8340VP-40 generator 180 kg

I didn't see any specs for this starter battery either, but it does appear to be intended to run a 12V electrical system and starter instead of using the 48V PM generator to start. Assume the same 65 Ah as the rest - 22.5 kG

I don't know exactly what pack Oceanvolt intended to supply, but the heavy end of the likely range would be 5x Torqueedo 48-5000 - $5200 each, 36.5 kg each - 182.5 kg total

Light end of the battery range - 6x tesla 85 modules:

https://www.evwest.com/catalog/produ...roducts_id=463

25 kg per, $1600 per. total 150 kg.

Oceanvolt system weight as described, 445-477 kg, depending on your assumptions about the pack.

Almost 200 kg lighter - 2/3rds the weight - even with the conventional system having a fancy lithium house pack that's 20% of the capacity (a lead acid house pack would have made this substantially bigger.)

The other thing to keep in mind is that Oceanvolt is a high-end - and high priced system integrator in the emerging electric drive market. The Tesla batteries with more capacity (32 kWh) are only $9.6k, and added to electric yacht's 20 kW saildrives at $13.5k each make a $37k system that's on paper more capable than OceanVolt's $79k:

https://www.bruceschwab.com/electric...ic-propulsion/

Of course, then you're playing system integrator and dealing with any reliability issues (the Tesla packs would also need an enclosure and BMS added.)

You'd presumably still want the generator in addition for motor-sailing situations, which would make the total something in the $60k range.

Thanks!


I'm not sure a 200kg difference means too much on a 10-12,000kg boat, but point taken.


My (much) smaller house bank in the DD system is due to personal usage, 460AH @ 12V would be more than enough for my usage.



I believe the market for OV compared to the market for DIY w/used batteries is a stark difference. But it does point out the costs for professional system integration.

[ssmoot]

Originally Posted by transmitterdan

You simply cannot motor for 8-12 hours on any EP system without a diesel generator.

Motor at 7kW. You need 84kW. Spend ~$18,500 to get 96kWh weighing about 700kg.

Originally Posted by transmitterdan

And it will likely take 24 hours hard sailing for the regen system to produce enough juice for 2-4 hours of silent motoring.

1kW average of regeneration. 10kWh/day of excess solar. 34kWh of energy.

"2-4 hours of silent motoring" is like saying "give me three feet of milk". If you want to hit 8kts you're probably right. If you're happy at 5kts then you'll go farther for longer on the same energy. Which means your next bit of sailing is closer. You need to start thinking watts in/out and stop thinking about blindly throwing the throttle to the stops. You don't do that on an EV on a road trip. I don't see why you'd make a habit of being similarly wasteful on a boat.

Originally Posted by transmitterdan

Less if you run all those appliances like aircon, fridge, freezer, water maker, etc.

Alternator amps burn diesel. They aren't free. These items don't have anything to do with EP or its viability.

Originally Posted by transmitterdan

Everyone wants the same thing you want, inexpensive to purchase, zero cost to operate with no noise or smell. The laws of physics say you can’t have it.

This has nothing to do with physics and everything to do with your own personal opinion.

Motors are cheap. Much cheaper than Diesel engines, which typically also rely on at least a couple of motors to function.

Now that some Chinese vendors are getting into the market, you can buy 10kW outboards for half the price of Torqeedo's offerings. It's only going to get cheaper from there.

Batteries are already cheap enough. If you feel comfortable servicing or replacing Lead Acid batteries, you shouldn't have any issues building a pack from Leaf Batteries, some bus bars, and a Batrium BMS. You won't have a warranty, but you won't need it since if a battery fails a year down the road it's $70 (currently) to replace it.

Here's what might be a standard setup with generator for a Seawind 1160:

Standard Gasoline Outboards with 3kW Generator

Honda 20HP Outboards (x2): $6,400
Next-Gen 3.5 Generator: $6,542
Victron Multiplus-II Inverter/Charger: $1,200
200ah House Bank: $1,500

Total System Cost: $15,642

Here's an electric alternative:

5kW AC Generator with a 24kWh bank

Golden Motor S20R (x2) $9,160
24kWh 48V Leaf Pack w/ Batrium Leafmon BMS: $5,000
Next-Gen 5.5 Generator: $7,900
Victron Quattro 48/5000: $2,545
Victron 48/12-20 DC Converter (x2): $200

Total System Cost: $24,805
System Premium: $9,163

But the more I think about it, the more I'm convinced I'd skip the diesel generator altogether. Especially on an 1160, which already carries gas. And I'd go all-in on solar (3kW+) and spend $2,000 on a pair of portable gas generators. Now I only need to carry one type of fuel for last-resort supplemental power and my dinghy.

Sure, I won't be motoring at 20kW for very long. Don't care. Because while sometimes nice, that's rarely necessary. And I'll have an abundance of battery power for things I do care about. Like running the air-conditioner occasionally, a powerful induction cooktop, unlimited fresh water and abundant hot water.

In the same way that it takes me a couple extra hours to drive to the in-laws a couple times a year in my Bolt, because I have to stop at chargers, I don't mind if passages take a few days extra out of the year.

If I'm only on passage 10% of the time, that means I've always got plenty of power the other 328 days a year without burning a single drop of diesel or ever turning on a generator.

During the 438 hours I'm sailing on passage in a year, I'm probably producing an excess of about 182kWh of solar I could use to make water, wash clothes, cook with electricity, motor later or point higher now if I'm full up and can't find a use for the excess.

If I'm ever at less than 100%, I can supplement with probably another 1kW regeneration while sailing. A potential 438kWh I can tap into.

During the 438 hours I'm motoring, I can draw down my batteries. Might have to run the generators some of the time depending on how long I have to wait for wind between bouts of motoring. Or if I'm not losing ground, I might just choose to wait it out and use 1kW or so just to keep on course.

And of course, the more miserly I am with motor power, the more that equation shifts into sailing and potential power generation.

It's a different life, but not a bad one I think. And I can always add a big 16kW generator later if I really felt the need. But I think being (mostly) silent, burning very little fuel, having far less (and cheaper!) maintenance to do, on a simpler system with more luxuries fits with what I hope to get out of the lifestyle pretty well.

In the same way that owning an EV requires the rare compromise for the overwhelming advantages the rest of the time (no maintenance, no gas stations, more powerful), I think a well designed EP boat is probably some inconvenience and compromise the 18 days a year everyone seems to agree you might be motoring (10% of the year on passage, 50% of that being motoring) for some very substantial advantages the other 95% of the time.

If I find 24kWh too much of a compromise, I can always double that for $4,500. Or quadruple it instead for $13,500 (no need to buy more BMS starter-kits, only the monitors, which are $34/battery).

I'd say at these prices EP is very viable (for multihulls with relatively clean salon-tops like Seawinds). And reasonably affordable for most people looking at $400,000+ boats. Certainly when you consider the outrageous markup on builder options for generators and sometimes engine upgrades (Seawind seems to be much better than most on engines at least). This is just another option, and it's not so outrageous as many.

[44'cruisingcat]

Originally Posted by ssmoot

1kW average of regeneration. 10kWh/day of excess solar.

We have 1000 Watts of solar. Our best day this summer has been 3.9 kWh.