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tesla motors idea for a boat Options
John Edward Mercier
#1 Posted : Thursday, August 28, 2008 5:07:47 PM
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Not sure. If your suggesting a perpetual motion machine? No. If your suggesting an electric boat? Yes. They already exist.

 

LaserBillA
#2 Posted : Sunday, August 31, 2008 1:04:24 AM
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The electric motor for the Tesla car is more than 70hp. I would look at the 2008 Prius motor at about 60hp.

The only way to charge the batteries using the prop(or any prop anywhere on the boat) would be to anchor the boat in a river.

FYI: I remember back when I was in first grade. I wanted to use water flowing down a slide to power a pump that would pump the water back up to the top... Luckily it did not take me long to to figure out that perpetual motion machines don't work.

Edit: A anchored Boat for river traffic might be a useful design in that you could use the same motor/generator and prop to charge the battery while docked and then use the battery to move up the river.
savoy special
#3 Posted : Monday, September 01, 2008 4:39:24 PM
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The motor is around 70 pounds, not horsepower. This motor is the size of a watermelon. I can't get the tesla website up right now but I know the horsepower of the motor was much higher than 70hp. I thought it was closer to 200hp. The battery lasted somewhere around 200 miles and the car traveled over 100mph.

To charge the batteries while on water, I meant for the prop while in motion would turn and send a charge back to the batteries. Or, while the boat was moving, there could be some type of turning wheel on the transom that would generate a recharge. These methods of charge could be a quick charge on the water like a cell phone quick charge. When you came into port, you could simply plug in for a deeper charge.

I understand that there are other electric boat motors but I haven't found any that travel at any decent speed. If this motor can push a car over 100mph, I can't see why it can't push a boat 50 or 60mph.

 

John Edward Mercier
#4 Posted : Monday, September 01, 2008 10:56:45 PM
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If the prop is propelling the boat through the water, it can not be used to recharge the batteries.

And if a secondary prop is used, the increased frictional drag will further hinder the original prop propulsion. No closed loop of this nature would work... frictional losses make it impossible.

 

savoy special
#5 Posted : Tuesday, September 02, 2008 4:07:55 PM
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Does anyone know where I can get my hands on a motor like this and batteries? I would like to give this a try.
walton2010
#6 Posted : Wednesday, September 03, 2008 9:20:49 PM
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You can always build your own motor (you will find that current models are quite forcibly controlled even in the used market place--hence, you will only find what you find). Another way is to buy a Tesla and rip the motor out???!!!! 

Batteries, you can find on the used market, but here too is an opportunity to build your own--the more people working on battery technology, hopefully, the better. 

 

Now, if you can build a wind turbine or solar powered  boat that cruises at a consitent 70 knots (and on demand) THAT would be impressive. 

 

Walton

davisonh
#7 Posted : Saturday, September 06, 2008 1:36:48 AM
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If someone can make a motor(dc or ac)that weighs 70# and develops 200 horsepower I'd like to know about it because I don't think its technically possible without some sort of superconducting going on.I think some math has to happen here because 200 x 746 =149200 watts or 149.2 kW.Suffice to say since the 100 ampere service of a house can only deliver 10-18 kW I'd say you're talking some pretty hefty power.

LaserBillA
#8 Posted : Saturday, September 06, 2008 2:43:00 AM
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I've seen a 20Hp motor the size of a car starter.

And the 60Hp Prius motor is not very large.

I don't know about 200HP motor the size of a watermelon since the power electronics alone would be larger than that right now. (give it a few years)

1. The Weight increases with the cube of the size.
2. The power increases slightly more than the cube of the size.
3. The power increases with the AC frequency.

On the other hand the motor itself could be quite small since the trend is High frequency Rare earth Magnet AC Sync motors. A ferrite armature with a
Rare earth Magnet core could be quite compact and powerful with AC frequency in the 10Khz range and a switching frequency in the 100Khz range.

To put that in perspective the weight of the motor's core will shrink with frequency. This means that at 10Khz the motor's core will be ~150 times lighter than a 60 Hz motor. Another factor to look at is that the power output per pound/size increases with size.


The other thing they are doing is using higher voltages. It's common to 500 to 600 volts DC now days. For example the Prius uses a boost converter to increase the battery voltage from ~190 volts DC to 500 volts DC. This cuts the current needed by the voltage ratio (600Volts/200Volts) or three times less current.

The one problem with all this is that the cost/price increases with the square of the power density. This means that these motors will be VERY expensive.
davisonh
#9 Posted : Saturday, September 06, 2008 10:30:46 PM
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On those issues I agree with you Bill,yes indeed a smaller motor's possible with those parameters but another problem is that hysteresis/eddy current losses must be enormous at that frequency range.I would also think that shielding the motor/controls would be of  importance because current load at those frequencies tends to impart electromagnetic fields in anything metal around it for a good 10-20 feet surrounding the device.An example of this are  MRI's.Seems to me a small 3 phase (or 6 phase,theres a way there to get over size issues also)synch.motor,possibly cooled with helium or using the vehicles A/C  would be the way to go to make smaller ac motors if ac is whats preferred.I agree, so much needs to be done on the issue of electrical storage.Whoever invents a battery that can efficiently deliver the current vehicle requirements is going to be a rich man.
LaserBillA
#10 Posted : Sunday, September 07, 2008 1:09:43 AM
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davisonh wrote:
On those issues I agree with you Bill,yes indeed a smaller motor's possible with those parameters but another problem is that hysteresis/eddy current losses must be enormous at that frequency range.I would also think that shielding the motor/controls would be of  importance

The normal steel lamination's limit most motors(AC or brush DC) to around 100hz.

There are some company that sell motors with really thin Steel lamination's that can work at 600Hz, but the future motors will probably use ferrite.

The wires from the Inverter to the motor have to be shielded for RF using a solid copper shield.

It won't radiate magnetic fields as long as the currents are balanced and the
armature magnetic design is balanced.

I also see the inverter having the air/"low ferrite" inductors needed to create a Sine wave to reduce skin effect and eddy currents in the motor.
John Edward Mercier
#11 Posted : Sunday, September 07, 2008 7:57:48 PM
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None of that matters.

The basic idea of using recharging the battery with the force initiated by the battery will not work.

Even if the electronics had no power depletion... the frictional losses of the hull and prop would be sufficient to drain away the battery.

 

LaserBillA
#12 Posted : Monday, September 08, 2008 12:39:17 PM
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John Edward Mercier wrote:
The basic idea of using recharging the battery with the force initiated by the battery will not work.

True, but there are two areas where you could charge the battery's
1. While anchored in a river.
2. While being blown by wind using sails.

I don't think either of these uses would be economic since the costs of the motor and battery's would be way too expensive compared to the cost of the fuel saved.
savoy special
#13 Posted : Wednesday, September 10, 2008 12:41:03 AM
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Sorry, this is a little long but this is what I was reading. I was also wrong about the weight of the motor. It was 115 lbs and not 70 lbs. If they can make all this work in a car, it will work in a boat. 

2009 Tesla Roadster

Technical Specifications*

Motor 375 volt AC induction air-cooled electric motor with variable frequency drive. Max Net Power 248 HP (185 kW) @ 4500-8500 rpm Max rpm 14,000 Efficiency 92% average, 85% at peak power Torque 276 ft/lb (375 Nm) @ 0-4500 rpm Transmission Single speed fixed gear with electrically-actuated parking lock mechanism and mechanical lubrication pump Overall Final Drive 8.28:1 Reverse Reverse direction of motor, limited to 15 mph Final Drive Ratio 3.12:1 Acceleration 0 to 60 mph in under 4 seconds Top Speed 125 mph (electronically limited) Range About 220 miles
(based on EPA combined city/highway cycle) Battery Life Five years or 100,000 miles Battery Custom microprocessor-controlled lithium-ion battery with 6,831 individual cells. Weight 992 lbs. Full Charge About 3.5 hours using the Tesla Motors High Power Connector.

The Energy Storage System (ESS)

When we set out to build a high-performance electric car, the biggest challenge was obvious from the start: the battery. Its complexities are clear: it's heavy, expensive, and offers limited power and range. Yet it has one quality that eclipses these disadvantages and motivated us to keep working tirelessly: it's clean.

The Tesla Roadster's battery pack — the car's "fuel tank" — represents the biggest innovation in the Tesla Roadster and is one of the largest and most advanced battery packs in the world. We've combined basic proven lithium ion battery technology with our own unique battery pack design to provide multiple layers of safety. It's light, durable, recyclable, and it is capable of delivering enough power to accelerate the Tesla Roadster from 0 to 60 mph in under 4 seconds. Meanwhile, the battery stores enough energy for the vehicle to travel about 220 miles without recharging, something no other production electric vehicle in history can claim.

Motor

Some people find it hard to imagine our car's Lamborghini-beating acceleration comes from a motor about the size of a watermelon. And while most car engines have to be moved with winches or forklifts, ours weighs about 115 pounds — a strong person could carry it around in a backpack (although we don't recommend it). Compare that to the mass of machinery under the hood of $300,000 supercars that still can't accelerate as quickly as the Tesla Roadster.

But more important than the motor's size or weight is its efficency. Without proper efficiency, a motor will convert electrical energy into heat instead of rotational energy. So we designed our motor to have efficiencies of 85 to 95 percent; this way the precious stored energy of the battery pack ends up propelling you down the road instead of just heating up the trunk.

 

savoy special
#14 Posted : Wednesday, September 10, 2008 12:41:03 AM
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Any reasons why this wouldn't work? A light weight electric motor such as the Tesla motor (somewhere around 70#'s I think) could be placed on a boat along with the same type of batteries (Lithium Ion). You could use the prop as a generator or even a separate wheel placed half way in the water to produce a charge. I know the weight of the batteries would be great but you could discard the large fuel cell and make up the rest of the weight in the motors. A good size outboard weighs around 300 -500#'s. Any ideas???  By the way, I talked to an engineer at tesla for over 30 minutes and everything I asked was like pulling teeth.

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