I don't know you still got me scarred (the boat stuff I really don't
know! ) so I'm re-going through all my figures. If your right and my
hull is 2/3 less efficient then a full displacement (any one have an
authoritative source? ) Then even with my pack being three time
bigger then any of yours (48v X 3 = 144v) that would give my the same
range as your boats with the same 200 AH pack at 48v. Now given that
lithium is twice as efficient for traction load then lead My boat will
still weight twice as much! So I spend three time as much to move
three times the boat the same distance at the same speed..... So what
do you guys get for range and speed???? lol I hope 60 miles!.
Don't get the impression I was arguing, I was not. I'm trying to
understand all the complexities, The electrical I think I have a firm
grasp of. The boating part is pure mystery.
On May 25, 2009, at 11:29 AM, aweekdaysailor wrote:
>
>
> I typo'd the $$ - $20K compared to the cost of gas over a long
> enough period does seem to hit the realm of "practical". I know it
> cost my neighbor about $10/mi (last summer) to run his smaller boat.
> So if ~13HP will push you along at 6kts it seems very doable -
> that's only a 2500mile payback period if gas goes up again - which
> I'm sure it will next summer.
>
> It's also great to hear lithiums have come down that much ($0.29/
> watt-hour was the lowest I saw on posts)- that's why I bought the
> cheapest deep-cycles I could find hoping they'd last long enough to
> where 200AH of LI (@48V) was available and reasonable. $3K is
> definitely in the ballpark and not much more than good SLA.
>
> So keep us informed as things progress - this could be a game
> changer for a whole bunch of old sedans here in the Delta :)
>
> So...back to props and such. Bigger is better is about all I know on
> the subject - the e-boat spreadsheet in the Files section is I think
> designed for displacement hulls, but would be a rough guide at least.
>
> -Keith
>
> --- In electricboats@
> wrote:
> >
> > 400AH/144v pack would run you about $20K, Or about $480 a cell with
> > BMS. You would need 44 cells. But still not chump change.
> > But I still do not see where you see all the lose at. I think you
> > assume I am all out all the time maybe 17 knots for three hours
> would
> > give me close to my 60 miles. ;-)
> > But putting around at 6 knots or so I am thinking I would be able to
> > putt all day? Hard to say till I have the motors in and can measure
> > the amp draw.
> >
> > On May 24, 2009, at 7:43 PM, aweekdaysailor wrote:
> >
> > >
> > >
> > > OK, so one assumption I made is that you have a planing, and not a
> > > semi-displacement hull. Those are not efficient at low speeds.
> If's
> > > its a semi-displacement trawler/tug type hull I'll reduce my
> > > guestimate by 2/3. But I just checked some pictures and they look
> > > like planing - and you mentioned it as well. I basically took
> 1/3 of
> > > 1 of your current engines for the 100KW guestimate.
> > >
> > > Let's say I'm off by a factor of 10. That's a 70amp draw off your
> > > 200AH of battery - 3 hours cruising. Or 6 if you pop $40K for the
> > > 400AH pack.
> > >
> > > At that point I'd say you're not only right, but far richer than
> I :)
> > >
> > > Stumbled on this: http://www.hawaii-
> > > which might settle the matter.
> > >
> > > -Keith
> > >
> > > --- In electricboats@
> > > wrote:
> > > >
> > > > 100KW to drive it at what speed? Please supply the math your
> working
> > > > in your head.
> > > > I would be curious what assumptions your making here.
> > > >
> > > >
> > > > On May 24, 2009, at 10:16 AM, aweekdaysailor wrote:
> > > >
> > > > >
> > > > >
> > > > > Denny is being too nice to say it outright, but what you're
> > > looking
> > > > > for isn't practical today. You'd be needing nearly 100KW
> > > continuous
> > > > > power to drive that boat -- a minimum of 12 100AH batteries
> would
> > > > > last about 4 minutes. So multiply by 10 -- 120 batteries to
> get an
> > > > > hour of range (Peukert helps here) at 80% depth of
> discharge. 120
> > > > > batteries is ~7000lbs...300 connections to corrode...740
> cells to
> > > > > inspect...and one bad cell to ruin your day (or hour anyway).
> > > > >
> > > > > Steyr has some sweet-looking but undoubtedly pricey hybrid
> diesels
> > > > > that might be worth looking at - that would give you a short
> > > period
> > > > > of "silent running" before needing to power up.
> > > > >
> > > > > Otherwise - you can "go green" using biodiesel in conventional
> > > > > engines. A 30' sailboat is near the practical limit for pure
> > > > > electric due to hull form and battery weight factors -
> that's why
> > > > > they tend to be the focus.
> > > > >
> > > > > -Keith
> > > > >
> > > > > --- In electricboats@
> > > > > wrote:
> > > > > >
> > > > > > James,
> > > > > >
> > > > > > HP is HP, whatever the prime mover. The continuous (not
> max or
> > > > > peak) power rating of your motor is the number to use.
> > > > > >
> > > > > > The battery bank is the real power constraint anyway, not
> the
> > > > > motor. You want to consider speed and range. Not much sense
> > > setting
> > > > > up an E boat that will go fast but drain the batteries flat
> in 5
> > > or
> > > > > 10 minutes. Start the design process by defining the speed and
> > > range
> > > > > you require, select a possible motor/battery system, evaluate
> > > cost,
> > > > > weight, performance. Repeat until you are confident you have
> the
> > > > > best compromise.
> > > > > >
> > > > > > Get Dave Gerr's "Propeller Handbook" to figure the prop
> size and
> > > > > rpm best suited to your boat.
> > > > > >
> > > > > > Google the "Peukert Effect" to see how rapid discharge
> affects
> > > > > battery capacity.
> > > > > >
> > > > > > You will be removing around 2500 - 3000 lbs from the boat.
> You
> > > new
> > > > > installation needs to maintain the original center of
> gravity or
> > > the
> > > > > boat won't float level and if it floats bow down maybe hard to
> > > steer.
> > > > > >
> > > > > > Good luck.
> > > > > >
> > > > > > Denny Wolfe
> > > > > > www.wolfEboats.
> > > > > >
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > From: James Sizemore
> > > > > > To: electricboats@
> > > > > > Sent: Sunday, May 24, 2009 3:25 AM
> > > > > > Subject: [Electric Boats] Any larger electric boat owners
> out
> > > there?
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > I see a lot of traffic on this list for smaller conversions
> > > > > replacing
> > > > > > A4's and such on 20-30 foot sail boats. Are there any
> folks that
> > > > > have
> > > > > > replaced larger motors on cruisers/trawlers?
> > > > > > I will be replacing two 427 fords (350hp gas engines) on a
> 41
> > > foot
> > > > > > Chris-Craft. This if for a number of reasons including not
> > > wanting
> > > > > > the ongoing expense of buying gas, second I really hate the
> > > > > monstrous
> > > > > > complexity of combustion engines. I have a computer science/
> > > > > > electrical background so I am much much more knowledgeable
> and
> > > > > > comfortable with electrical systems. And not to mention the
> > > smell
> > > > > and
> > > > > > noise of combustion engines. The knowledge I lack right
> now is
> > > boat
> > > > > > related: prop size pitch ...etc...etc. I don't need the
> boat to
> > > > > plane
> > > > > > at 17 knots or anything like that, although if it does all
> the
> > > > > better.
> > > > > >
> > > > > > My current thinking is to replace the fords with a pair of
> > > (Netgain
> > > > > > Warp 11'' or Transwarp 11'')'s. The part I can not rap my
> head
> > > > > > around is if I go direct drive with the Transwarp's will
> they
> > > spin
> > > > > the
> > > > > > props to fast? Or should I keep the transmissions that the
> > > fords are
> > > > > > bolt to now and go with the Warp's. I would prefer not to
> have
> > > the
> > > > > > extra complexity of the transmissions. The Netgains can
> move a
> > > large
> > > > > > truck at freeway speeds 70+ MPH. My understanding of the
> > > > > conversion of
> > > > > > electrical hp to combustion hp is at 144v these motors
> should be
> > > > > about
> > > > > > the equivalent of a 150-200 hp gas motors with
> considerable more
> > > > > > torque at the low end.
> > > > > >
> > > > > > The boat will soon have a fairly large solar array and
> already
> > > has
> > > > > > 7.5 KWH generator. So keeping the battery bank feed should
> not
> > > be a
> > > > > > problem. I know finding a solar charger/inverter for a 144v
> > > battery
> > > > > > pack will be a real challenge. Any recommendations are
> > > welcome. I
> > > > > > would also be very curious of other conversions of larger
> > > plaining
> > > > > > hull boats, and what motors you use and performance you
> get now.
> > > > > Also
> > > > > > any recommendations on motors/charges/
> for
> > > boats
> > > > > > this size would be most welcome.
> > > > > >
> > > > > > [Non-text portions of this message have been removed]
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > [Non-text portions of this message have been removed]
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > >
> > >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
[Non-text portions of this message have been removed]
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