T-Pain Is On A Boat: [Electric Boats] Re: New Member and New Electric Boat Conversion

Monday, August 10, 2009

[Electric Boats] Re: New Member and New Electric Boat Conversion

Thanks Patrick - very nice report on a well-done rig. (I need to find those nice insulators on your motor)

I am also encouraged by your regen numbers - is that a 2-blade or 3-blade prop? Also what type? That's getting into the range of practical - for example 200watts is probably near your house load.

But I would caution you on estimating your total usable capacity. For those batteries, I get a calculated Peukert exponent of 1.17 - among the lowest available in lead-acid which is great. But I show only 66AH available at a 75AH rate (to 80%) even with your 126AH rating on those batteries (Peukert still strikes) - so basically 45-50 minutes of total runtime (ignoring solar and regen). Doubling the batteries would give you ~2 hours of runtime - about 130% gain on 100% investment.

My main concern would be that you inadvertantly run those nice batteries below 80% and greatly shorten their life.

http://sites.google.com/site/electricboating/Home/batteries/peukert (my simpleton explanation on Peukert)

http://www.odysseybatteries.com/files/US-ODY-TT-001_0108.pdf (specs)

Nice job and hope this helps!

-Keith

--- In electricboats@yahoogroups.com, Patrick Muran <element359@...> wrote:
>
> Good Evening,
>
> It is exciting to see the possibilities of electric boats and I can now say that I now have experienced the possibilities of what electric boats have to offer.
>
> Here is my basic profile.
>
> Boat: Serendipity 43' 1981 IOR race boat.
> Displacement: 17,000
> Draft: 8'
> Beam: 13'
> Old Power: Pathfinder 50HP diesel
>
> The goal of my re-power was to integrate the powerful rig for regeneration and solar power into an electric motor configuration that I can use for day sailing which at the moment is 95% of my usage.
>
> Here is some of the data we received from our recent trip from Santa Barbara to Channel Islands Harbor (~30nmi).
>
> Propulsion Marine 4.7 KW inboard electric drive
>
> Mars 4.7 KW brushless permanent magnet AC motor
>
> Sevcon Millipak controller
>
> Browning 3301 gearbox with 4.87:1 gear ratio
>
> Propeller 17 x 17 Left hand which required you to change the fan on the motor
>
> dripless stuffing box by PYI
>
> 4 Odyssey 2250 batteries with 6.3 KWH total energy,   5 Kilowatt hours of usable energy.
>
> 3/0 x 10 feet cable run from batteries to controller
>
> propeller turns at 470 rpm, motor turns at 2288 rpm, draws 85 amps on a bollard pull, 70 amps at 3.7 knots
>
> solar powered using two Sanyo 200 watt panels and Outback Flexmax 60 charge controller.   Have witnessed 400 watts charging current.   Capable of Solar motoring which adds about 1 knot to speed by negating propeller drag and adding a small amount of thrust.
>
> Regenerates at 200 watts at 6 knots in light breezes, more is expected in heavy breezes because boat has previously logged 10 knots boat speed in 25 knots of wind.
>
> On our test sail from Santa Barbara to Oxnard in light breezes we witnessed 570 watts of total generation consisting of 370 watts of solar power plus 200 watts of regeneration.
>
> Batteries were refilled in 2 hours after discharge from harbor maneuvering
>
> The system was professionally installed by James Lambden, Above the Waterline
>
> www.abovethewaterline.net in Santa Barbara
>
>
> http://www.propulsionmarine.com/vesper.htm
>
> Cheers,
>
> Patrick
>
>
>
>
> [Non-text portions of this message have been removed]
>