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Old 19-03-2018, 18:00   #1246
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Re: Oceanvolt Hybrid Motor

Thanks Octopus for your suggestion to use supercapacitors. I am six months from completion but will be research their use. They appear to be perfect for the short high loads of anchor winches etc.
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Old 19-03-2018, 18:06   #1247
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
"For short duration high-load 12V accessories, like winches, windlasses and generator starter, you could look at using fit-and-forget supercapacitors, charged by your 12VDC low-load circuit, located close to the point of use, to provide the oomph required."

Where could I find out more about these high load caps? Are you sure they would handle the load from a loaded 1,500W windlass? Have you done it?

At this point it seems prudent to have a separate 12V bank for high loads for that equipment. I cannot find a 48V/12V DC converter that can handle the load reliably.
I don't think you will find them. The main component inside is unobtanium which is difficult to mine.

Some math: to run a 50A 12V windlass for 1 minute with 2V drop would require a capacitor of 1,500 Farads. C=I*T/dV=50*60/2
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Old 19-03-2018, 21:27   #1248
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Re: Oceanvolt Hybrid Motor

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Originally Posted by scooter.john View Post
Thank you Chris for your valuable experience. You have got me thinking about 240 volt for high load circuits. How is this more efficient than 48 volt.
Bottom line, is if you are asking this question, you should get some focused experienced help as you work through this. In the mean time here's a bit of background on why different voltages are better in different circumstances that might help.

The key for boat electrical systems is the equation Power = Volts x Amps. This means that to get a given amount of power through a wire or out of a motor, the higher the voltage the less current is required. Reducing current is important because wiring must be sized based on current. Simplistically, twice the current requires twice as big a wire, or put another way twice the voltage requires half the size of a wire for a given amount of power. There are two key implications, the higher the voltage of your system, the thinner and lighter the wiring can be (but not the insulation), and for things like electric motors, higher voltage means the same power motor can be smaller and lighter.

So why are boats generally 12 volts, not higher? A lot of it comes back to the history of car electrical systems. To start with the basic cell of a lead acid battery is roughly 2v, so the higher a voltage required, the more cells are required for a battery. Originally cars were 6 volts (3 cells), but as power requirements went up, particularly for lights and starter motors, rather than running thicker wires, the voltage was bumped up to 12v (6 cells), and now up to 24v in some commercial vehicles.

Because cars are 12v, there are many more mobile electronics and electrical components available at 12volts, which means even though boats could benefit from the smaller wiring that comes with higher voltages, they would suffer with needing much less common and more expensive electrical components. You will however see some bigger boats going to 24 volts and biting the bullet on more expensive components and stepping down to 12volts for components only available in 12 volt versions.

There's another aspect which is safety. Once voltages get to around 50v they start to be more dangerous. The risk of electrocution starts to get real. Please note, that there is always the risk of burns whenever you have significant currents regardless of the voltage. Just drop a wrench/spanner across the terminals on a 12v battery to see the result. So heading up to 240 volts has a real safety impact that you need to take account of.

So deciding on on the voltage for a system usually comes down to at least the following issues:
- wiring weight and sizing
- availability of components/loads at the designed voltage
- motor sizing and efficiency (propulsion, windlass, pumps, refrigeration, ...)
- batteries are not really the issue, you can just put more in series to get the voltage you need
- availability of chargers and inverters for the design voltage
- safety
- multiple systems for multiple voltages

So, yes think about higher voltages for high load applications, but do it in the context of all the other issues with designing a complete electrical system. In your case, you are likely to design around the voltage of your chosen propulsion system, and then probably have a second lower voltage system for "regular" components.

Mark.

(Edit: note this is about DC systems. Much of the same applies for AC circuits, but don't confuse the two)
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Old 19-03-2018, 23:37   #1249
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Re: Oceanvolt Hybrid Motor

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Originally Posted by mark_morwood View Post
Bottom line, is if you are asking this question, you should get some focused experienced help as you work through this. In the mean time here's a bit of background on why different voltages are better in different circumstances that might ....
Good explanation.

It's basically balancing the market size vs cable size.
- On small boats, devices usually have small power draws and since the lengths are short, reasonable sized cables can be used with low voltage (12v), so taking advantage of the much larger (and often cheaper) 12v device market makes a lot of sense.
- As boats get larger, power draw for items like windlasses and bow thrusters along with just about everything else get's larger. In addition, the length of cable runs gets longer. This mean you would need massive cables if you stick to low voltage. At some point, it makes sense to go to higher voltage to reduce the cable size even though the end devices may cost more and it may be harder to source replacement parts.

Example: I was working on a project (land based) where the power source was around 2000' away. The client didn't want to use transformers to boost the voltage...the net result was copper cables 1.5" in diameter. When we showed them the price of those cables, suddenly transformers were fine to use.

Half a dozen voltages just makes for a messy system that will likely cause more problems than it solves.

PS: 12v for starting engines is usually fine as the runs are usually very short and the demand is only for a few seconds, so overheating cables is less of a concern. For EV, with constant demand and much greater draw than a starter motor, upping the voltage makes a lot of sense but it is usually treated as a separate decision as not many DC devices are available above 24v.
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Old 20-03-2018, 00:00   #1250
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Re: Oceanvolt Hybrid Motor

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Originally Posted by scooter.john View Post
Thank you Chris for your valuable experience. You have got me thinking about 240 volt for high load circuits. How is this more efficient than 48 volt.
The main factor is that the market for AC appliances is far larger with more competition, so there is more incentive to design efficient appliances and mass production makes more efficient designs cost-effective. This applies to things like washing machines, fridges and freezers, but not to everything.

Chris
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Old 20-03-2018, 00:04   #1251
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by scooter.john View Post
Thanks Octopus for your suggestion to use supercapacitors. I am six months from completion but will be research their use. They appear to be perfect for the short high loads of anchor winches etc.
This was just a suggestion. I've no experience of them, but I know people are starting to use them for high-load applications. It's something I'll be looking into when I have more time. Super caps look like a fun thing to explore, if you enjoy that sort of thing.

Chris
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Old 20-03-2018, 00:52   #1252
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Re: Oceanvolt Hybrid Motor

Hi Chris (Octopus)


Good to see you are still around and still using hybrid after all these years. I was just wondering how much time you've spent aboard the boat over the years, how many hours you've put on the generator and how many times you've replaced the batteries? Do you know how many 420s have stayed with the original hybrid system?


I did meet Steve (Dignity) several times at various places around the world. He always said it was a great system and the problems people had with it was because of its use in charter boats where the users just didn't know how to get the best out of it.
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Old 20-03-2018, 01:55   #1253
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Re: Oceanvolt Hybrid Motor

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Originally Posted by 44'cruisingcat View Post
Don't really see that doing that would offer much benefit. You have to have 48 volts for the drives anyway. If you want a biggish inverter, running that off 48 volts would make sense. Big reduction in current. I'd probably be looking to use the 48 volts for as many big load items as possible, for that reason. A 48 volt windlass might be nice....

Maybe you could skip the 24volts circuit, if you really want to eliminate one?
I would check the safety issues with 48V in a salty atmosphere. 48V DC is quite safe in fresh water conditions but I'm not so sure about salt water flooding over the windlass.
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Old 20-03-2018, 10:20   #1254
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Jeannius View Post
Hi Chris (Octopus)

Good to see you are still around and still using hybrid after all these years. I was just wondering how much time you've spent aboard the boat over the years, how many hours you've put on the generator and how many times you've replaced the batteries? Do you know how many 420s have stayed with the original hybrid system?

I did meet Steve (Dignity) several times at various places around the world. He always said it was a great system and the problems people had with it was because of its use in charter boats where the users just didn't know how to get the best out of it.
Hi Mike, yes I'm still around, more in theory than in practice at the moment, owing to work and family pressures.

Steve was a great champion of the hybrid, but even he succumbed to the temptation to convert to conventional diesel in order to sell Dignity, before his untimely death. I imagine there are a few other stubborn die-hards like me out there, but no more than a handful. Really the 420 hybrid was ahead of its time. I'm trying to re-invent Octopus as a better hybrid, by replacing the lead acid batteries and the Lagoon-developed control system, but I have a lot of other things on my plate at the moment.

Octopus is still on her second set of propulsion batteries, although these must be on the way out by now, which is why I've just purchased a LiFePO4 pack and am gradually assembling the components for the charge control system. I'll try and get the systems running in parallel and once I'm happy with the new system I'll rip out the Lagoon control system and dispose of the batteries. I'll still keep the heart of the Lagoon system: the generator, motors and variator motor controller (VSD).

Chris
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Old 25-06-2018, 23:28   #1255
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Smile Re: Oceanvolt Hybrid Motor

Hi all,
I would like to share our experience with our 50 foot catamaran with Oceanvolt SD15s and a 25kWh SuperB battery bank if anybody is interested. We have now cruised for 9000 nm from La Rochelle to Panama.
We have worked very closely with OV to tweek the system on our blue water cruise to get it into a real world electric/hybrid propulsion system. It is running great now, thanks to their support. We are extremely pleased now. The target was to run the boat continuously at around 7 knots as a requirement to pass the Panama channel. And we can now run the boat as we expected.
On our journey we motored from the BVI to the Dominican Republic for 200 nm! There was no wind, just for a stretch of 40 nm we could sail. The propulsion worked well and we got there fine. We have a Fischer Panda 22 kW genest that supplied the electricity nicely.
If there are any questions we can answer we would be happy to answer.
This is the future we believe and it works fine even on a 20 Ton cat.
All the best
Jan-Dirk
SV JaJapami
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Old 26-06-2018, 03:00   #1256
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Re: Oceanvolt Hybrid Motor

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Originally Posted by JaJapami View Post
Hi all,
I would like to share our experience with our 50 foot catamaran with Oceanvolt SD15s
Very interesting! We have been cruising with a 50 ft cat for three years having ordinary 40 hp engines.
What is your experience with going against wind, 20 knots headwind or more. What is realistic with the SD15s?
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Old 26-06-2018, 03:11   #1257
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by JaJapami View Post
Hi all,
I would like to share our experience with our 50 foot catamaran with Oceanvolt SD15s and a 25kWh SuperB battery bank if anybody is interested. We have now cruised for 9000 nm from La Rochelle to Panama.
We have worked very closely with OV to tweek the system on our blue water cruise to get it into a real world electric/hybrid propulsion system. It is running great now, thanks to their support. We are extremely pleased now. The target was to run the boat continuously at around 7 knots as a requirement to pass the Panama channel. And we can now run the boat as we expected.
On our journey we motored from the BVI to the Dominican Republic for 200 nm! There was no wind, just for a stretch of 40 nm we could sail. The propulsion worked well and we got there fine. We have a Fischer Panda 22 kW genest that supplied the electricity nicely.
If there are any questions we can answer we would be happy to answer.
This is the future we believe and it works fine even on a 20 Ton cat.
All the best
Jan-Dirk
SV JaJapami[emoji2]
Hi, I am also interested in OV, did you have them installed from new? If so did you save much space on fuel tanks or did you keep the original?

Regards

Heath
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Old 26-06-2018, 03:55   #1258
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Re: Oceanvolt Hybrid Motor

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Originally Posted by myocean View Post
What is your experience with going against wind, 20 knots headwind or more. What is realistic with the SD15s?
Around Martinique we headed directly into 28-32 knots of wind. At that time we could not yet use as much power as today because the motor controllers didn’t have active cooling fans installed limiting the power to 8 kW port and 7 kW starboard (very the genset heats up the engine room in addition). We were going at SOG around 3 knots. Our friends on a Lavezzi with original diesels did 3.5 knots full power.
It seems that the torque of the SD15s let it go forward into the wind pretty efficiently considering the size of a Saba. When we have 15-20 knots head on we loose about 1 knot.
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Old 26-06-2018, 04:07   #1259
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Heath68 View Post
Hi, I am also interested in OV, did you have them installed from new? If so did you save much space on fuel tanks or did you keep the original?
Hi Heath, we have the original tanks installed. They are under the aft cabins‘ beds so there wouldn’t be a great advantage not to have them there. We have a transfer pump installed to pump from port to starboard. In total we have a capacity of 940 liters of diesel. Usually we don’t fill up the port tank but for long passages it is useful. it would give us a range of 1500 nm motoring. The nice thing about our configuration is that we have very tidy engine compartments with lots of room inside. The weight of the 12 SuperB batteries is roughly the same as the Fischer Panda genset. In total we saved 300 kg compared to the standard 55 hp Diesel engines.
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Old 26-06-2018, 05:32   #1260
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by JaJapami View Post
Hi all,
I would like to share our experience with our 50 foot catamaran with Oceanvolt SD15s and a 25kWh SuperB battery bank if anybody is interested. We have now cruised for 9000 nm from La Rochelle to Panama.
We have worked very closely with OV to tweek the system on our blue water cruise to get it into a real world electric/hybrid propulsion system. It is running great now, thanks to their support. We are extremely pleased now. The target was to run the boat continuously at around 7 knots as a requirement to pass the Panama channel. And we can now run the boat as we expected.
On our journey we motored from the BVI to the Dominican Republic for 200 nm! There was no wind, just for a stretch of 40 nm we could sail. The propulsion worked well and we got there fine. We have a Fischer Panda 22 kW genest that supplied the electricity nicely.
If there are any questions we can answer we would be happy to answer.
This is the future we believe and it works fine even on a 20 Ton cat.
All the best
Jan-Dirk
SV JaJapami
Interesting! Does the genset output always goes through the battery bank, or can it goes directly to the engine? And do you know the efficiency compared to "bare diesel"?

And how about hydrogeneration when sailing, did you use that a lot?
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