# Project Star-Lord, Electric Trawler Conversion



## brian_ (Feb 7, 2017)

jddcircuit said:


> I will tow the boat about 20 miles in the water to my house where the electric conversion and topside restoration will happen.
> With all the weight I am removing I am a little concerned about ballast and stability.


It seems to me that the solution for this concern is straightforward: a bunch of concrete blocks, and presumably suitable lumber under them, piled in place after the engines are removed.



jddcircuit said:


> I have no idea about expected performance.
> It will likely not be fast.


That should be straightforward to work out. Assuming that it is a displacement hull, there are readily available formulas to calculate the power requirement versus speed for a known length of waterline and weight of boat.



jddcircuit said:


> I want to mount 15 300W solar panels to it. When the boat is not in use I plan to feed the solar power to my home.
> ...
> Battery capacity is TBD. The batteries will be the most expensive part of the conversion.


I assume that you intend to charge all of the time and use power for propulsion for only very short periods. Battery capacity will need to be enough to get you back to port with no solar input in the worst anticipated weather from the maximum distance that you are going from port, plus a reserve. A complete pack salvaged from an EV might be a good start. At least you don't have to worry about battery weight...



jddcircuit said:


> I will use salvaged Prius motors for each shaft. I will weld the axle differential rigid and use MG2 (larger traction motor) via the 4:1 gear reduction to the propeller shaft.
> I will couple the boat shaft via a rigid mounted thrust bearing to the Prius half shaft.
> 
> The extra motor (MG1) inverter bridge will be used for a solar charge controller boost and a single phase house inverter/ battery charger.


Why... are Prius transaxles with inverters really cheap? It just doesn't seem like an obvious choice, with MG1 and the power split gearset being completely surplus, but perhaps salvaged EV motors are too much more expensive.

I assume that the prop shafts run directly from the engine crankshafts, so at engine speed. What is that speed in cruise?


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## jddcircuit (Mar 18, 2010)

sand bag ballast may be prudent until I back fill with motors and batteries

The hull is very sailboat like which is why I picked it. I am hoping for efficient low speed cruising. The calculations may be straight forward but haven't tried that hard yet. My napkin math tells me to target a 1000rpm propeller shaft which seems similar to wheel speed of an EV. Then pitch the prop accordingly in the future.

The Prius components are the most inexpensive and readily available EV components AFAIK. I plan on buying two complete Prius cars to part out.

I can salvage the dual inverter, transaxle, half shafts, battery, cables and connectors, accelerator pedal, power steering, AC compressor, 12V DC/DC converter, wind shield wiper motors, coolant pumps, contactors, etc.

I also already have some prototype software and hardware to control the Prius inverter working for motor control and battery charging.

Thanks for your comments


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## Duncan (Dec 8, 2008)

The Prius parts may be the cheapest - but they are also the most useless for your purposes 
If you have already bought them.....
If not DON'T

With marine propulsion bigger and slower are best - you should be looking at the maximum size of prop that is usable with your hull and working from there

Cheapest way would be two forklift motors - they go for about $200 each here (NZ) 

In fact for your boat the later AC forklift motors plus their controllers would probably be ideal as you don't need high rpm's or a lot of power

Batteries from a Leaf, Tesla, Volt ...


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## jddcircuit (Mar 18, 2010)

Oak Ridge National Lab report for 2004 Prius show a locked rotor test for the motor.

https://www.osti.gov/servlets/purl/921783

The chart shows a peak torque of 339Nm at 250 amps. Gear reduction of 4.113 gives 1394Nm at the propeller shaft. This should be enough I would think.

I'm betting the Prius components will prove to be ideal for marine applications with oil/liquid cooling and sealed gear reduction housing.

The large DC motor I just pulled out of the bow thruster had rusted brush springs and seized bearings. I am not sure if it is salvageable.

DC motors don't interest me much

Comparing motor types
Prius Locked Rotor torque tests








Forklift motor torque curves


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## piotrsko (Dec 9, 2007)

Your forklift list doesn't include typical manufacturers of forklift motors, just ev motors.


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## NiallDarwin (Sep 29, 2018)

Have you seen Damien messing with Prius motors and controls?
https://www.youtube.com/user/pooey1911
Could be useful to you


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## jddcircuit (Mar 18, 2010)

piotrsko said:


> Your forklift list doesn't include typical manufacturers of forklift motors, just ev motors.


if you have additional forklift motor information feel free to post.
However, I don't think they are the right motor for this project.


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## jddcircuit (Mar 18, 2010)

NiallDarwin said:


> Have you seen Damien messing with Prius motors and controls?
> https://www.youtube.com/user/pooey1911
> Could be useful to you


I have seen some of Damien's videos in the past. Thanks

Quite a while ago I made a motor controller for the Prius transaxle. I plan to knock the dust of it and start with that.


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## RIPPERTON (Jan 26, 2010)

JDD are you planning to regen tidal current while anchored ?


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## jddcircuit (Mar 18, 2010)

RIPPERTON said:


> JDD are you planning to regen tidal current while anchored ?


I will test it but I don't expect much effect.

I am probably going to try and keep one of the Prius gas engines as a generator especially with the amount of energy consumption to be determined.


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