Author Topic: Electric Drive  (Read 469 times)

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Offline Owly055

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Re: Electric Drive
« Reply #20 on: May 14, 2017, 10:44:48 AM »
220 amp hours is 73.3 amps for 3  hours or 3520 watts.  That's 4.72 HP before the gearbox, probably closer to 4-4.5 HP real world shaft horsepower.    Take your 4 cycle outboard or inboard, and calculate how much power it takes to move the boat at 3.5 kts based on fuel consumption per hour.   1 gallon per  hour is very close to 12 hp.   You should be able to cruise at 3.5 kts on .29 gallons per hour if their numbers are correct.    Typical 4 cycle gas engine efficiency with a fairly efficient engine is .5 pounds of fuel per horsepower hour, and gas weighs 6 pounds per gallon.   Two cycles can burn anything from 50% more upward, often as much as double.  There is no accurate way to calculate horsepower based on fuel consumption on a two cycle, though direct injection engines will tend to burn about 20% more than good 4 cycle... about .6 gallons per hp per hour.  That would be something like the Etech or Optimax.

                                                                 H.W.

Offline misfits

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Re: Electric Drive
« Reply #21 on: September 05, 2017, 02:34:39 PM »
Finally got this thing 95% complete. Should have the batteries next week, we'll see if she spins.
I'm not happy unless I'm complaining about something.
I'm having a very good day!

Offline Frank

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Re: Electric Drive
« Reply #22 on: September 05, 2017, 04:04:06 PM »
Look forward to the report.
Hope it exceeds expectations for ya!!
God made small boats for younger boys and older men

Offline Norman

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Re: Electric Drive
« Reply #23 on: September 05, 2017, 04:38:05 PM »
Excellent start on the electric motor drive.  The transmission integrates beautifully, and the motor room is in fine shape.

Did the instructions emphasize getting perfect shaft alignment?  I see a flexible shaft coupling, and many motor manufacturers depend on them to get SATISFACTORY alignment.  All flexible couplings have some wobble unless the shaft  is perfectly aligned, and wobble eats shaft seals prematurely.  The arrangement that you have makes perfect alignment relatively easy, especially since the motor is relatively light weight.  It seems that you can raise or lower by simply adjusting the nuts on the support threaded shafts, if there are nuts also under the metal support plate.  The life of the flexible coupling is also extended by lack of actual flexing.

An aluminum roof over the motor itself, easily removable, and far enough away to prevent blocking air flow will keep condensation from dripping into the motor in changing weather.  All water on a boat is conductive, and causes corrosion and short circuits.  This is a "stitch in time" modification.

I have repaired two generators with "moisture" failures, one was simply mouse pee, the other was condensation.

Again, the setup is coming along nicely, and I am happy to see that the picture problem is solved, and we see just what you have done so far.

Norman


ralay

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Re: Electric Drive
« Reply #24 on: September 05, 2017, 05:26:36 PM »
Looks professional.  I'm interested to hear how it goes.  I was just reading a back issue of Wooden Boat with an article on a solar electric power boat.  The owners seemed really pleased with its performance. 

Offline misfits

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Re: Electric Drive
« Reply #25 on: September 06, 2017, 11:44:50 AM »
Thanks for the kind words.

The flexible coupling,  you're right about alignment being critical just as it would be with any transmission to shaft coupling. The reason for the flexible coupling on this installation is to electrically isolate the drive from the prop shaft.

The cover idea, crossed my mind. I considered  having a piece of aluminum bent up so I could mount the controller & contactor on the drop pan next to the motor. Toss a cover over the whole contraption, you not only protect it fbutrom moisture but now the drive & it's components are enclosed in a faraday cage..

I'm not happy unless I'm complaining about something.
I'm having a very good day!