Hi George.
You are very correct, the 6V batteries golf cart type seem to work well, I understand they
have heavier lead plates to take the higher current. I am holding out for the Firefly Oasis
batteries group 31 slated for delivery in August. They can take 80% discharge over 800
time, plus they have negligible charge capacity drop off from discharge cycles.
Kevin Plank the owner of Re-E-Power is getting his charge capacity from the controller an
ALLTRAX AXE 4844 or 4845,..... ala golf cart. At least that is what he started with. His
desire is to keep costs low and use off-the-shelf ruggedized components. That is good
for you and me, but think recently he has had a recall or upgrade of the controller. Those
controllers are still the weak link. The recommended cruise current is based on his tank
testing.
I sent in inquiry to E-jet just to see if they respond. They may be too new or not yet a fully
developed product. http://www.e-
Hubner-Braun version of the Voith-Scneider cyclodial prop. I think the harryproa
challenge is to make whatever propulsion appear to belong on the boat and not an
afterthought. So far it all looks cheesy. It's already visually handicapped as people prefer
symmetry, I don't want another dipstick in the water look, if it can be avoided.
Gonna put a proa boat in fab soon ? WE need some more ducks on the pond !
Cheers,
JT
--- In harryproa@yahoogrou
>
> Hello JT
>
> Just a note on the lead acid batteries , unless you are running over one or two hundred
amps they work fine (6volt T145 of T105 Trojan or similar gulf cart batteries) I had a
converted Nissan with 20 6VDC /120 VDC I would run 100 to 150 amps at 60mph and
would run up to 300 or 400 amps during acceleration with a 500 Amp controller. The car
is still in use daily by my son for commuting to work in St Peters burg Fl . The batteries
are 6 volt Trojan flooded lead acid over 6 years old. Another brand that is considered
good for EV.s is US battery. If you want sealed batteries you should use 6 volt gel cell gulf
cart (or 12 volt)which are considered better for deep discharge than AGM's. 8 volt gulf cart
size batteries are also a posibility but they are only available in flooded lead acid. The
AGM's are used on the drag strips for max current when you need short power burst for a
1/4 mile with over 1000 Amps by some electric drag cars.
>
> The 170 amp continuous for the RE-E-Power 3000 was taken from the specs given on
their web sight so I do not know where the discrepancy is. In any case if you actually
purchased a system you would have to confirm all the specs and details which may change
over time.
> Have a nice day,
> George
>
> jjtctaylor <jtaylor412@
> Hi George,
>
> I conversed with Kevin Plank and it is true you could run a 3000 system motor at a
higher
> wattage. BUT he states a 3000 motor can only run continuously at 80 amps or the
MOTOR
> will overheat. The controller itself can run at 170 amps continuously, yet not the motor.
> AND it is true you can run 400 amps but no more than 10 seconds or so, much like a
bow
> thruster. Therefore his literature states now a max recommended cruise of about 60
> amps. Devil in the pesky details. While he won't extrapolate how long you can run over
> 80 amps since that depends on water temp, etc. just know you won't be able to do that
> indefinitely.
>
> The back end issue is batteries, AGM can handle higher discharge rates, while others like
> typical lead acid don't like it. Lot's of new battery technologies coming available soon.
> Firefly by August 08.
>
> So just be VERY careful about elec motor sizing. Max HP of a diesel can be run for
> extended periods without damage so just be sure the motor rating is matched for both
> the short and long term running. Nigel Caulder spells it out very clearly in his review in
> Professional Boatbuilding. 4KW (48V x 80amp) is still 5HP+ and while that performs
> MUCH better than a larger diesel at low rpm, the diesel will continue to drive that prop
> rpm up to its higher RPM using its peak HP capability. All a function of the torque
curves.
>
> The comparison performance levels at RE-E-Power are very misleading. From what I can
> find a honda 9.9 HP power prop puts out about 250 pounds of thrust. That is a just a
> little more than a 4KW elec drive. Just validate your complete needs and all will work out
> well for happy cruising. I like electric myself. Just a challenge to get it all together
> without excess weight.
>
> JT
>
> --- In harryproa@yahoogrou
> >
> > Hello, JT
> > You are correct in that the electric is good for low speed with a flat torque curve. But
> if the motor is sized correctly its power should not be a problem. It should be pointed
out
> that you can not make a direct comparison of the HP since a gas or diesel is rated at
max
> HP and an electric is rated at continuous HP. An electric rated at 48 VDC,170 amps
would
> be 10.94 HP but the same motor may have a max HP twice this amount which can be
used
> for short duration. The Re-E-Power system 3000 is rated at 170 amps continuous but
> has a max of 400amps ! Of course you could not pull this much amps for vary long. I do
> not think that a gas or diesel engine would last vary long if it were run at full throttle
> continuously.
> >
> > There are other reasons to go with a electric drive, they are quieter, cleaner, simpler.
> But if you think you need a diesel you can install a diesel generator to supplement the
> battery pack for more range and to provide electric for the boat.
> >
> > One factor that may be overlooked though with electric is the power capacity of the
> controller. This is as important or more so than the power of the motor. If you have a
> motor with a 10 kw capacity but a controller with only 8 Kw max output you will limit
the
> output of the motor.
> >
> > Happy sailing,
> >
> > George Kuck
> > Chestertown, MD
> >
> >
> > jjtctaylor <jtaylor412@
> > Just two cavets to electric drives. As many profess electric has low
> > speed advantage over diesel with a flat torque curve all the way up
> > to max rpm. Great for harbor maneuvers. They don't have more power
> > than a diesel of similar rating. Check Profesional Boat builder
> > earlier this year, think Jan & Feb for detailed analysis by Nigel
> > Caulder. So if you are pinned off a lee shore make sure you have
> > sufficient HP or KW to move forward.
> >
> > #2 If you pod mount off a rudder, your steering rudder, then you can
> > expect an autopilot to not handle it well. If at ALL ! The
> > autopilot tunes to rudder response versus boat performance. The
> > drive will cause it to overshoot and thus will be extremely diffciult
> > to dampen. If the pilot ever manages to eventually tune to work, if
> > you change thrust on the electric motor the tuning will fail again.
> >
> > JT
> >
> > --- In harryproa@yahoogrou
> > wrote:
> > >
> > > G'day,
> > >
> > > Blind Date is getting an electric motor this winter. The 66'ter in
> > Portugal
> > > and the 60' charter boat are both planning on having them as well.
> > >
> > > Putting them on the rudders solves the two way problem and gives
> > amazing
> > > maneuverability. Would only need one if it was powerful enough.
> > No real
> > > drawings yet, but the principle is a sleeve that slides up and down
> > on the
> > > rudder blade with the motor attached to it. Lift it clear of the
> > water when
> > > not in use with a block and tackle, ease the rope to lower it.
> > Much cheaper
> > > and more reliable than the African Cats system. Kicks up on
> > impact and
> > > very accessible for clearing ropes and stuff off the prop. Also
> > (smug
> > > grin) not usable by boats without beam mounted rudders.
> > >
> > > Another version is the e jet http://www.e-
> > >
> > > regards,
> > > Rob
> > >
> > > On Thu, Apr 3, 2008 at 10:26 PM, chesapeake410 <chesapeake410@
> > > wrote:
> > >
> > > > Hello,
> > > > I am planing on building a 12 m Harryproa and am thinking of using
> > > > electric pods. Pods would be mounted on swing arms similar to what
> > > > has been used on African cats. Take a look at the June 14,2007
> > press
> > > > release on Africancats.
> > Power.com .
> > > > In the Re-E-Power Forum link in the photo section is a example of
> > a
> > > > pod mounted to a long swing arm.
> > > >
> > > > Has anything been done with electric power on Harryproa's ? I
> > think
> > > > there was a recent reference to electric motors on rudders, does
> > > > anyone have more information or pictures on this.
> > > >
> > > > I think a Harryproa would be unequally suited to a solar/battery
> > > > electric drive system since the sail is offset on lw hull. A solar
> > > > canopy over the seats a center area of boat would be less
> > obstructed
> > > > by sail than a cattermaran.
> > > >
> > > > The proa does have the problem of how to deal with going in both
> > > > directions with the electric drive. You could point one in each
> > > > direction and only use one in open water and lower both for
> > > > maneuvering in harbor or for extra power when needed. You could
> > use a
> > > > prop designed for both directions but I do not know it it would
> > be as
> > > > efficient as one designed for one direction.
> > > >
> > > > I would like to hear any sugjestions and comments one this ?
> > > >
> > > > One other concern would be the added weight of a battery pack
> > which
> > > > could be as much as 1000lbs or more. I am hoping that newer
> > battery
> > > > types will bring down the weight in the next few years to less
> > than
> > > > 600 lbs.
> > > > Valence Technology Lithium batteries would be great but the
> > current
> > > > price is prohibitive. Firerfly batteries (a new lighter type of
> > lead
> > > > acit battery) sound like a good bet but are not yet available. It
> > > > may be necessary to start with current lead acid and switch to
> > > > lighter batteries in the future. After Lithium batteries get
> > > > established in electric cars that will start coming out in the
> > next
> > > > few years I expect availability and price to improve. I spoke with
> > > > Bob Lutz vic chairman of General motors at a special event a the
> > New
> > > > York Auto show a week or two ago and he claims that they will have
> > > > the Chevy Volt in production by the end of 2010 ! It will run on
> > > > lithium batteries.
> > > >
> > > > Thanks for any imput on this topic,
> > > >
> > > > George Kuck
> > > > Chestertown, MD
> > > >
> > > >
> > > >
> > >
> >
> >
> >
> >
> >
> >
> > ------------
> > You rock. That's why Blockbuster'
Access,
> No Cost.
> >
>
>
>
>
>
>
> ------------
> You rock. That's why Blockbuster'
No Cost.
>
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