Elon Musk's New System -- Good for Boats?

[jongleur]

Whatever happened to the idea of swapping out
a discharged battery for a charged one? Some
buses use this system. If there are going to be
loads of unused/unsold batteries, Tesla can give
them to gas stations/recharging stations who
could keep a supply of charged batteries on hand.
They could corner the market with proprietary
tech.

[transmitterdan]

The packs in the Tesla are heavy and they are liquid cooled. As long as that's the case swapping is a non-starter. Not to mention they are under the car in an inaccessible location to lower the center of gravity.

Also, if people had to pay the "filling station" the true cost for the electricity they burn the miles per dollar (or kilometers per Euro) would make them pretty unappetizing. Right now a lot of these cars are getting charged up but somebody else is paying for the electricity. A battery swap system at a for profit service center would change the economic equation. Then people could compare with fossil fuel on an even unit of measure. The electric car can't win in that contest.

Who is going to pay for the extra packs that have to be put in circulation? It would probably double or triple the number of packs needed. That capital cost has to be amortized out plus a profit.

[SV THIRD DAY]

Originally Posted by TacomaSailor

The batteries being discussed here are $3,500 for 10KwH so I would need 12 10KwH batteries at a cost of $42,000. Assume they weigh 310 pounds each – that is 3,700 pounds of batteries. ( A 300 amp hour 8-D LeFePO4 weighs 93 pounds and can deliver 3 KwH when discharged 80% so 10KwH would weigh about 310 pounds)

Now, how do you recharge that big battery bank?Tell me how electrical propulsion makes sense for a cruising sailboat.

What is wrong with my analysis based on 13,000 NM of cruising and 15-years of living with only solar power on the boat?

Tacoma....you just boiled it down and shows us (reminded us) why it doesn't work (yet). Look, we all want it to work so bad and we get all excited, but then you run the numbers and Sha-zam...you just can't make the physics work yet for a real cruising boat. You just can't beat the Btu's stored in that evil, dirty diesel tank and yanmar engine.

Oh it can work for a "get me in and out of the harbor boat", but are you going to take that down Baja to Mexico and South America where you only have a few hours of motoring before you have to "just wait for solar to recharge the bank"? Those of us that have actually been out cruising know what the dreamers don't...that is cruisers motor a heck of a lot. Oh I know I know...there is always the exception that uses 5 gallons of diesel fuel per season with 15hrs of diesel motor time...but come on, that ain't the norm and what does that mean? It means power...power to motor more than you can get from wind and solar and battery bank.

It's ok to dream.
It's ok to hope.
But cruising boats don't really run on dreams and hope, despite what the glossy magazines and marketing say.
Ducked back in hole...start the arrows.

[SV THIRD DAY]

Originally Posted by transmitterdan

Tesla can't move enough cars to justify the big plant thus they need more demand for batteries. That's what this press release is really about.

If the technology is so good and makes sense....
They why....why can't they or the other electric car's out there get people to buy them?

Hey don't get me wrong, I would buy a Tesla S if I had $80K laying around to play with, but that's what it is at the moment...PLAY, not commercial reality for the masses.

[hellosailor]

"Whatever happened to the idea of swapping out
a discharged battery for a charged one?"
Supposedly the Tesla battery packs are designed to be hot-swapped, but that has not been implemented yet because of the extra complications. You'd need to have "swap stations" with staff and inventory, not just charging posts. And then there's another problem: I've got a new Tesla with a new battery. You swap in a battery from a 2013 Tesla. Hey, I don't want that, I came in with a NEW battery, at some point, how will I get stuck with an old dying battery instead of the one I just bought?
Kinda like the propane bbq tank swaps, except you're not arguing about a $100 tank, it's a $25,000 "tank".


Tesla and the Nooze apparently are both complicating issues because there are two very different Tesla home units proposed. The wall pack will just be a wall pack, about 3kwh for around $3500 "to the trade" not the end user. Then there will be a "home" pack around 10kwh at $25,000, which includes an AC inverter all whatever else is needed to make it your "mains" voltage for the entire home, even off the grid long term. The home unit will have thermal management (heat and cool) built in, the wall unit....damfino. Given the fine attention to scientific and technical points in The Nooze these days, I'm surprised they haven't announced Musk is going to use hyperloops to send Teslas to Mars.

[Stumble]

Originally Posted by SV THIRD DAY

If the technology is so good and makes sense....
They why....why can't they or the other electric car's out there get people to buy them?

Hey don't get me wrong, I would buy a Tesla S if I had $80K laying around to play with, but that's what it is at the moment...PLAY, not commercial reality for the masses.

Keep in mind the Tesla 3 is supposed to hit the market at $35,000 with a 200 mile range. Or right where the BMW 3 series starts. Who knows if they will hit the target price, but battery supply is dependent on the Gigafactory being up and running. And the price is likely as well.

So far Tesla hasn't been very good at hitting production deadlines. So I wouldn't bet that it hits the market on time.

[med]

Originally Posted by jongleur

Whatever happened to the idea of swapping out
a discharged battery for a charged one?

This was implemented in Israel for a Renault electric car

http://en.wikipedia.org/wiki/Renault_Fluence_Z.E.

The company doing the battery swaps rapidly went out of business. I do not know if the swap stations are still operating or if you are limited to charging your car at home.

The real world mileage was about 60 miles for these cars before you needed to do the swap.

[hellosailor]

Med, Israel was chosen because it is a very small country. Think of it like New Jersey: You simply CAN'T take a six hour drive without needing your passport.


Now, if Mr. Musk were to make a deal with Uber, perhaps? You know, drive 200 miles, abandon your Tesla to be charged, and some Uber guy will take you to your destination while that's happening, and pick you up again, so there's no range anxiety?


Solution in plain sight! Throw in a car wash and a pine freshener on the mirror....

[med]

Originally Posted by hellosailor

Med, Israel was chosen because it is a very small country. Think of it like New Jersey: You simply CAN'T take a six hour drive without needing your passport.


Now, if Mr. Musk were to make a deal with Uber, perhaps? You know, drive 200 miles, abandon your Tesla to be charged, and some Uber guy will take you to your destination while that's happening, and pick you up again, so there's no range anxiety?


Solution in plain sight! Throw in a car wash and a pine freshener on the mirror....

Correct - and there are not many different main routes either.
They could not get it to work there - with a big investment.

So not much chance of getting it to work anywhere else either.

[Aargau]

Wow, the misinformation in this thread is strong.

• Batteries are internal/external and sealed but, yes, not currently stated as designed for marine use.
• Cost is ~$300 per kWh, but in CA there is also a 60% tax rebate. This will likely go away soonish.
• People worrying about battery fires while running internal combustion engines haven't learned what "combustion" means, or they've read stories without understanding the Dreamliner 787 fire design issues and how it relates to Tesla.
• The Tesla car batteries since 2014 are designed to be swappable in 90 seconds. There is a battery changer in King City, CA that currently swaps them out in 3 minutes.
• You don't need to keep 50% charge. That's for lead acid or AGM.
• The car is expensive, but the Model 3 will be $35,000 with 250 mile range.
• There are thousands of places to plug in if you don't own a home. Plugshare.com shows quite a few of them.
• If you go with an all electric yacht drivetrain, you'll be able to reverse charge with the props as well as solar, so no, you don't need every inch covered.
• The stock is highly valued, precisely because it is disruptive technology. Elon has said Tesla is a battery company, not a car company. Driving prices down on batteries is disruptive. Building gigafactories to build more gigafactories is really the story. Not only will battery production scale, but so will battery factory production. That's what might be hard to intuit.
• The Tesla cars see about 20 hardware changes per month, including 5 improvements to batteries in the last 2 years. I just got a software update that took my car 0-60mph from 3.1 seconds to 2.97 seconds.
• Elon also runs SpaceX, that NASA depends on to resupply the International Space Station. He's recently nearly perfected rocket systems that re-land on their launchpad after going into space. Never doubt his ability to execute.

I've driven my Tesla P85D from Silicon Valley to Seattle and back, all for free, and in 16 hours by stopping at the supercharger network. It charges at 360V and up to 350A, and surprisingly no one has died with such voltages and amperes (at least that's the reply I'd expect from some people on this thread).

The wonderful thing is technology is moving forward, with missteps here and there, but it's moving forward. Without even knowing the science behind it, and to poo-poo it, is the mark of a Luddite. Google is your friend, there's simply no point in posting "I don't know what this does, but I bet it doesn't work". However, I'm always up for changing my mind based on evidence. We all should be. The great thing is you get to choose whatever path you want, as do all of us, and history will determine who was correct.

[Aargau]

On a personal note, my entire family almost died from carbon monoxide poisoning. I had to fireman carry them all out unconscious to fresh air. I know a few friends who have lost loved ones from CO. It's the #1 poisoning both in homes and on boats. I will be very happy to build a non-diesel system even though the energy density isn't there yet for solar/battery/electric drivetrain.

Did you know even low level chronic exposure to CO is bad for you? The kind where you're in a marina berth and the guy next to you's pollution is drifting right through your space.

Here's a somewhat old report on CO and boating, but I believe it is still the case as the #1 killer in live-aboard boating.

http://www.cdc.gov/niosh/topics/cobo...aselisting.pdf

Finally, it's so weird to be a sailor and hear people defending diesel motors on sailboats as old-school. It's entirely possible to go everywhere by sail, everything else is a modern convenience.

[hellosailor]

" but the Model 3 will be $35,000 with 250 mile range."
Speaking of misinformation, they have said they are anticipating a 200 mile range, not 250. And a price of $35,000 in 2017, based on the gigabattery factory coming online in time, and at full capacity. ll quite nebulous and speculative right now.


Tesla is also the company that sued the NYTimes and one of their reporters, after the reporter published an article about his trip in a Tesla and the repeatedly bad advice as to range and recharging that the company and car gave him. Apparently because Tesla doesn't understand the concept of "winter". It is now two or three years since the incident, and the reporter and the Times cannot discuss anything because it still has not gone to court, or been settled.


Not that newspapers never mis-state facts, but they had no axe to grind. The range and direction errors are typical for "nav" systems and range changes that every other car company has found in winter.


Tesla has changed their range calculations since then, but of course, that's just an improvement, not a correction.


No thanks. I've done 400-600 mile legs with only a ten minute fuel and pee break. In a Tesla? Stopping every 200 miles for maybe a half hour? Nah. I could lose an extra 25% roadtime on a trip if everything went "right". If it works for you, and you never need to push the envelope, great.


Let the rest of us know when it can work for everyone, everywhere, every time. At $35k actual price, not "anticipated".

[TacomaSailor]

"Wow, the misinformation in this thread is strong. "

As is the mis-understanding of the propulsion demands of a long distance cruising boat.

All this excitement about the new “Tesla Wall Battery” has led me to do some number crunching. I wanted to understand how a boater might recharge those very nice BIG batteries. I wanted to compare fuel consumption per nautical mile for my old Yanmar diesel to a state of the art diesel electric boat.

I want to share the detailed calculations to see if someone from the electrical propulsion proponent group can tell me what I’ve calculated incorrectly.

Lets assume we motor 140 hours per year at 6 knots, which is pretty typical of my engine use for the last 20 years. My Yanmar 4JH2E needs 11 HP to the prop at 2100 RPM to move Mirador, a 12 tons 40’ cutter, at 6 knots.

A brief summary of my results when comparing the diesel electric boat to my Yanmar boat:

If we can use a small diesel AC generator that recharges the batteries at 1/3 the rate we discharge them –we use 12 gallons less diesel than does the Yanmar. That number changes to 26 more gallons than the Yanmar if we recharge batteries at twice the rate we consume battery power to move the boat.

During the 20-years I’ve owned Mirador I would have used 240 fewer gallons of diesel if a 48-volt traction motor with lots of batteries powered it. That would have saved me about $1,000 at current diesel fuel prices.

And, I would have put 7,800 hours on the generator.

The new Tesla batteries may be a break through in battery technology but the charging mechanism needs a lot of improvement before it is economical or practical to use them in a cruising sailboat.

Here is a more detailed summary based on Brake Specific Fuel Consumption (BSFC). The following is the pounds of #2 diesel burned to deliver 1 KwH to the Propeller.

NextGen 3.5 Kw BSFC 0.55
Northern Lights 10 Kw BSFC 0.87
Norhtern Lights 20 kw BSFC 0.81
Yanmar 4JH2E 7.5Kw BSFC 0.63

The NextGen is 11% more efficient than is the next best energy source, which is the Yanmar diesel directly driving the propeller. The NextGen diesel is sized and geared to run at its most efficient speed, and therefore has a relatively low BSFC. My Yanmar, at 2100 RPM, is running 1000 RPM below its minimum BSFC, which would be 18% lower than achieved at the 6-knot speed.

The NOISY problem with the NextGen 3.5 Kw is that it needs 3 hours run time to replace one hour of energy used while cruising at 6-knots. If we motor 8-hours to get to the next anchorage then we run must the generator 24 hours to recharge the batteries.

Here is a more detailed analysis with lots of numbers.

My boat cruises very nicely at 6 knots/2100 RPM while burning 0.64 GPH diesel fuel. The propeller curve in the Yanmar 4JH2E manual shows that to be 11 HP at the prop as does the much more complicated required propulsive power formulas from Bebe’s handbook on cruising under power.

The Yanmar BSFC is 0.474 pounds/hour/HP while running at 2100 RPM (best BSFC is 2800 to 3300 RPM but is still .40 pounds/Hour/HP ‘cause it is an old mechanical injection engine). That converts to 0.63 BSFC for pounds / KwH DELIVERED TO THE PROPELLOR.

For oceanic passages I assume that we must be able to motor at 6-knots for up to a continuous 24-hours (196kWh). What kind of a generator would be needed to replace 180 KwH consumed while motoring? (The REAL question is “where I can find room on the boat for 20 10kwH Tesla Wall Batteries discharged to 100% or 30 discharged to 33%?”)

Lets assume the generator is 100% efficient because the manufacturer gives us measured GPH to deliver the rated Kilo-Watts. However, modern battery chargers for 48V / 100 amp golf cart or traction devices are only 85% efficient at converting the 120V AC power into 48V DC power to apply to the batteries.

And, modern high efficiency traction 48V traction motors are only 90% efficient at using the power supplied by the batteries while spinning the propeller.

Therefore, the recharging system needs to return 1.31 KwH to the batteries for each KwH used to power the boat [ 1 / (.85 x .90) ].

The 2nd determinant of recharge system is “how fast to I need to recharge the batteries?”

I have used rounded numbers below to approximate within a couple percent the exact numbers.

To recharge at the same rate we use power then we need a 11 Kw AC generator. ( Northern Lights 10 Kw Lugger generator is 16.5 HP, weighs 700 pounds wet and burns .9 GPH at rated Kw )

If we are more optimistic, i.e. we sail three times as much as we motor, then we can recharge at 1/3 the rate we consume power, which leads to a 3.5 Kw generator. ( NextGen 3.5Kw is 7 HP, weighs 210 pounds wet with sound shield and burns 0.2 GPH at rated Kw)

If, in the interest of safety we want to recharge at twice the rate we consume Kilo-Watts then we need a 21 Kw generator. ( Northern Lights 20 Kw Lugger generator is 32 HP, weighs 1000 pounds wet and burns 1.7 GPH at rated Kw )

Let’s now calculate the BSFC for each generator and compare it to the BSFC for my normal Yanmar propulsion diesel (pounds diesel / KwH )

NextGen 3.5 BSFC 0.42
NL 10 Kw BSFC 0.66
NL 20 kw BSFC 0.62
Yanmar BSFC 0.63

BUT, we need to make 1.33 KwH at the generator to have 1 KwH available at the prop so each BSFC needs to be increased by 1.31.

NextGen 3.5 BSFC 0.55 & run time of 298 hours
NL 10 Kw BSFC 0.88 & run time of 104 hours
NL 20 kw BSFC 0.83 & run time of 52 hours
Yanmar BSFC 0.63 & motoring time of 140 hours

Assume we motor 140 hours (840 NM) a year at the specified 6-knots. The extra diesel fuel used by each generator, compared to the Yanmar, is:

NextGen 3.5 -12 gallons
NL 10 Kw +34 gallons
NL 20Kw + 26 gallons

The new Tesla batteries may be a break through in battery technology but the charging mechanism needs a lot of improvement before it is economical or practical to use them in a cruising sailboat.

[hellosailor]

"http://www.cdc.gov/niosh/topics/cobo...aselisting.pdf"
An incredible number of HOUSEBOATS and vacationers, not sailors on sailboats. You've only found the reason why WalMart doesn't sell heavy construction equipment: The average idiot should not be allowed to buy it. Plenty of common things kill plenty of people each year, there's no scathing report on CO to be found there. Better to ban beds and couches, because cigarette fires kill so many people sleeping in them every year.


And how pray tell did your family get attacked by who's CO?


The Tesla predictions for volume of scale and price for the Gigafactory ouput, all are based on a 15x increase in the number of Tesla cars (35,000 now, 500,000 then) by 2020.


That's a terribly speculative figure. And still using thousands of 18650 cells for each pack, which is also a lot of labor and material that larger prismatic cells don't have.

[TacomaSailor]

"If you go with an all electric yacht drivetrain, you'll be able to reverse charge with the props as well as solar, so no, you don't need every inch covered."

How does that work? The really BIG question is:

Is there a mechanism to make the propulsion motor produce less electrical power when being used as a generator while being spun by the prop?

If I install a electric motor big enough to power at 7-knots, 20 Kw, then how do I keep that motor, when recharging the batteries, from exerting so much drag that I can’t get the boat to sail?

20 Kw is the power needed to move the boat at 6.9 knots. If there is less wind than would move the boat at 6.9 knots, about 15 knots apparent on a close reach, then will the boat move at all?

If we can control the drag the electric motor places on the prop then how much will the boat slow down when charging the batteries?

Assume I want to recharge at 1/4 the rate I take power out of the battery.
That would be roughly 2 Kw drag at the prop. and would allow 6.2 Kw of power for propelling the boat forward.

6 Kw propulsive effort will move the boat at 4.6 knots so a 25% recharge rate will slow the boat by 1.4 knots.

At 7.3 knots, a reasonable reaching speed for us in 18-knots wind, the boat needs 22 Kw power at the prop. If I want to replace the power used at 6-knot cruising speed the prop would impose 8 Kw of drag and slow the boat to 6.6 knots.

That does not seem practical to me. What have I misunderstood?