Electric Cruiser

I mean the problem is really the 60kWh battery and the charging at land. If like you say 6.6 kW pushes the greenline33 to 6 knots you can go 9 hours. If you need more range you can go 4 or 5 knots.

If you build with LiFePO4 batteries yourself the cheapest (if you buy in bulk from china) is probably something like 300-400€ / kWh. So 24.000€. Plus cables, charger and a good BMS. Personally I'll stick with 48V. Building with 18650 batteries isn't going to be fun but cheaper at 250€/kWh. The HBPowerwall guy has the process pretty much perfected and just build a 25kWh battery out of 3000 cells.

With an inboard motor you could maybe also combine multiple smaller motors to drive the same shaft with the same gearing. Maybe that makes cost of motor and controller cheaper. Not sure if that makes any sense.

 

It makes perfect sense to me. And like I said, the Model 3 battery packs, complete with BMSes and charger, cost around $10K lightly used, and they’re 80 kW raw, built of 2170 cells.

 

By using a Model 3, you are dealing with high, lethal voltages. The legal and safety requirements are hard to meet. DC electric motors and controllers for those voltages are expensive, particularly for wet installations.

 

High voltage motors lower the current and therefore, use smaller wires. They pull very heavy loads.

The voltage isn't the dangerous part.

Considering the efficiency of induction motors, it might make sense to invert to AC power in the 1k+ volt range.

Comparison of high voltage motor and the advantages and disadvantages of low voltage motor-Anhui Wannan Electric Machine http://men.wnmotor.net/article/504.html

-Will (Dragonfly)

 

I think the safety issue gets complicated and you'd need to consult an expert. I *think* in a dry environment high voltage with enough amps to deliver 10kW is far more dangerous do humans because unlike 48v it can bridge the skin. And AC is less dangerous because it gives muscles a chance to let go off some conductive thing. But in saltwater it might different again. But even with perfect contact I think the resistance of the human body is high enough to not have strong currents flowing through your flesh and start to char / burn.
So personally I'd stick with 48V and rather spend more on bigger cables.

PS: And lol that picture. Probably the ozone generated with do most harm

 

You might be right. Tesla died at the age of eighties-six, in an era not known for its enlightened medicine nor healthy eating philosophies. Not to bad for a guy who spent so much time exposed to energy forms we still know little about.

-Will (Dragonfly)

 

That comment does not make sense, it seems you are simply being argumentative. Firstly, Tesla was an unparalleled genius who eat a vegetarian diet throughout his life, and in his later years milk, honey, bread and vegetable juices. Secondly, the old and tired argument that current kills, not voltage only shows your lack of understanding of basic electricity. The high voltage generators that are use in science class and for toys have a very high online resistance when a human body is connected in series. Do the diagram for a Model 3 battery with a human body and no online resistance and calculate the current.
https://www.cdc.gov/niosh/docs/98-131/pdfs/98-131.pdf?id=10.26616/NIOSHPUB98131

 

Lets listen to the world renowned expert on being electrocuted:

 

Wasn't being argumentative, only augmentative.

I stand corrected. I have had classes in electricity for my computer science degree. It just shows how closely I paid attention. Thanks for the correction.

-Will (Dragonfly)

 

What is your point? Are you saying that Ohm's Law does not apply to your system? At an estimated 1000 ohm for moist skin, which is usual on normal climatic conditions, the current would be 0.375A for 375V. That is lethal.

 

So what's the point of being concerned about either the voltage or the amperage for the system? Killer volts? Killer amps? There are dangerous aspects to any system used to propel a boat, particularly ones in the size I'm talking about. Fuel can burn or even explode. An engine can throw a rod right through the casing. In any case, handle the systems correctly and be mindful of the dangers.

I do understand that if someone is considering a DIY approach to an electric boat, they need to be mindful of how to handle the various components correctly during installation. But once installed, and the system sealed, there should be little to no reason to interact with any of the components. Compare this to a diesel propulsion system, where every 200 hours you have to change the oil, and daily when in use you need to check the sea water strainers and other checkpoints. Got a gas engine? Be sure to run the blower to clear the engine room of dangerous fumes before starting the engine. How many boats have caught fire or blown up because of trapped fumes?

 

According to your philosophy a sealed system does not need to be inspected ever. That is a really bad policy and terrible design. All systems need access for inspection, maintenance and repair. There is no such a thing as killer volts or killer amps. An electrical system, for DC can be analyzed with Ohm's Law. A human body, or parts of, are treated as a resistance.

 

JDRay, do you plan to DIY or find someone to build this for you or looking for a turnkey solution? Just out of curiosity.

 

I would like a turnkey system, but can't reasonably afford it. So, for me, the next best bet is to find an appropriate ICE-powered boat and have someone knowledgeable (New Electric, for instance) convert it. The next option after that, which would take me a lot of time to learn the various disciplines necessary, would be a DIY conversion. I think the having-a-boat-converted option is most likely, since doing one myself would involve long term rental of a facility and time I don't have. Better to leave it to the experts.

 

If you are going to hire an engineer, you will be told what several already did about safety, cost, etc. Experts are going to be more expensive than buying an off the shelf system. Custom designs take time and money for design, testing and adjusting. All prototypes need a fair amount of work after they are finished. You need to figure out if you have the money to afford a project like this. You will spend a lot more than a boat with a new diesel in it.