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post #71 of 84 Old 11-18-2015
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Re: Would anybody be interested in an electric outboard like this?

Does this new battery need a "solar stick"?
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post #72 of 84 Old 11-18-2015
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Re: Would anybody be interested in an electric outboard like this?

I remember, Hunter I think, came up with an Electric powerplant and used the keel as the Battery probably 15 years ago. I wonder what happened to that idea.
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post #73 of 84 Old 11-18-2015
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Re: Would anybody be interested in an electric outboard like this?

Quote:
Originally Posted by Captain Canuck View Post
If you watch the video, they use a contra-rotating prop design, which makes sense. Contra-rotating (two propellers spinning in opposite directions, but with opposing blades so they both pull in the same direction) are an old trick to get more thrust from the same power. Older (40s-50s) airplane designs could get ~20% or more power with them. The tradeoff is they are a bit heavier (not much of a problem on a boat) louder (again, underwater, so who cares) and mechanically much more complex. The complexity is what got them dropped from aircraft use, even though they could produce modern jet-like speed. The fastest contra-prop commercial airliner clocked in at 500mph, but was a maintenance nightmare. That was 50+ years ago, though, so maybe the mechanical issues are more easily overcome with modern materials.
Volvo penta patented the duo prop in 1982 The benefits of Duoprop - DPS Duoprop : Volvo Penta so its not a new technology BT the patent may have run out allowing this company to finally use it.

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post #74 of 84 Old 11-23-2015
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Re: Would anybody be interested in an electric outboard like this?

For anybody interested, here is a link to their facebook page with several videos and images of the battery packs on the boat.

https://www.facebook.com/PureWC/?fref=ts
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post #75 of 84 Old 12-06-2015
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Re: Would anybody be interested in an electric outboard like this?

I have a 20' 2500# sailboat that I strictly daysail on Lake Michigan. The system you describe would be completely overkill for my boat. I get by with a 30# Torqeedo 1003 (20# motor, 10# battery). I can go in and out of the slip (about 15-20 minutes each way) and come back with 75% battery power. It does push me somewhat slow...3-4 knots, but I don't have to deal with smelly gas, ethanol fuel problems, and it is virtually maintenance free. It also has GPS and tells you you range. It's easy to bring the 10# battery home to charge. I'm on a slip, but if you were on a mooring you could use the motor on a dingy to get you out to the boat, and switch it to the sailboat. The cost was not bad...$1600 on sale. It was completely trouble free the 1st season.
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post #76 of 84 Old 12-12-2015
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Re: Would anybody be interested in an electric outboard like this?

Let me clarify a few points. I started Pure Watercraft, the company that the OP was studying. This project was for a UW entrepreneurship class, and the students came here to this forum to find out what the market thought. This was not posted by Pure Watercraft or anyone working on our behalf. Our system is in engineering prototype stage, not yet in production.

Some of the details they posted were right, and some were not. I want to make sure we leave this forum with the right info, directly from the source.

POWER
Our motor is rated at 20 kW continuous power. That translates directly to 26.8 HP; however, our prop is indeed more efficient than existing props, so it gets more propulsion than a gas motor of the same power. (Reasons: gas outboards run ~ 3000 RPM, while we run ~ 1500 RPM, with larger diameter prop, and we have full torque starting at 0 RPM, while gas motors have very narrow RPM zones in which they reach rated torque. Proof: we consistently outrun boats with 30 HP gas outboards, both from a dead stop and at top continuous speed. Gas motors would use more efficient props, too, if they would work well at both low and high speed, but they would not, because of the very low torque gas motors produce at low RPMs.)

We will market our outboard at different power levels, because there are distinct markets for them; however, it will be the same motor inside. So if you get the 9.9 HP version, you can run on lakes that limit power to < 10 HP and be legal, but get more propulsion than others with 9.9 HP gas outboards.

RANGE
Our outboard does not go full throttle for 3 hours (without an inordinate volume of batteries). With a single battery pack it can go 27 minutes at 12 kW, and with two battery packs it can go 33 minutes at 20 kW.

If you use two battery packs, and go for 3 hours at constant power, using the full usable capacity, you'll be using about 3.7 kW, which is about 5 HP, and the propulsion would be equivalent to about 6-7 HP from a gas outboard. With a low-wake launch, we go about 10 mph at that power. So our range with that hull is about 30 miles with 2 battery packs running at 3.7 kW. Your speed at that power would depend on your hull, of course, and I'm sure nearly everyone on this forum knows exactly how fast they would go at that power.

BATTERY PACKS
Our motor works exclusively with our own battery packs. We focus exclusively on high performance systems; there is no sense in combining our very high power density motor with very low energy density batteries (especially because our voltage would drive an impractical setup of 12V batteries). Our packs can be combined for larger capacity. Using our own packs exclusively allows us to run more safely, as we can ensure affirmative communication between battery pack and motor in every case, and prevent running under adverse battery pack conditions.

Our battery packs have nominal capacity of 6 kWh and usable capacity of about 5.5 kWh. Voltage is 350V, which allows us to achieve much higher power density than other electric outboards (more than double that of the lower-voltage Torqeedos, for example). In prototype, our battery packs weigh 99 lbs, but we expect that the production version should weigh less (maybe 85 lbs?).

For those who compare our energy density to that of LiFePo4, ours is better, because Li-NMC is an inherently more energy dense chemistry. We include a thermal limiting material in our battery packs to ensure they keep at a healthy temperature.

CHARGING
We have two chargers: 120V 1 kW, and 240V 10 kW. The math on charging times is pretty straightforward; if you use 2/3 of a 12 kWh system (two battery packs), then using our 1 kW charger, it will take about 8 hours to nearly fully recharge (there is some additional time at the end to balance the cells). Our packs have a charging speed limit of 1/2 of their capacity per hour (to preserve battery health and cycle life), so even with our 10 kW charger, you could only charge at 6 kW if you were using two of our battery packs. The chargers can each charge multiple boats and battery packs at once.

OUTBOARD MOTOR
It weighs 91.8 lbs in prototype, and should weigh about 15 lbs less in production. The motor is in-line with the 8:1 gear set and the prop, underwater, so the noise is very low. Its efficiency is very high, partly due to the high voltage, which leads to lower current and lower heat losses.

TOTAL SYSTEM WEIGHT
Our minimum total system weight in prototype is 190 lbs, and in production we expect it to be about 160 lbs. With two battery packs (which is the minimum configuration to get our total rated power of 20 kW), our system weight is 289 lbs in prototype, or expected weight of about 245 lbs in production.

For comparison, an equivalent power gas motor to our minimum configuration is 15 HP. The Honda 15 HP weighs 104 lbs. Add a 33 lb starter battery and filled 3 gallon gas tank (20 lbs) and you get a total system weight of about 157 lbs. So our production system is at virtual weight parity (albeit shorter range).

An equivalent gas motor to our 2-pack configuration is 30-40 HP. The Honda 30 HP weighs 160 lbs. Add a 33 lb starter battery and filled 6 gallon tank (40 lbs) and you get a total system weight of about 233 lbs. So our production system is about 12 lbs more (but again, lower range).

In each case, it's important to note that our weight comes mainly from the battery packs, so the transom weight is much less than with a gas outboard.

HULL
It's true that we use a low-wake, efficient hull for testing. Batteries are expensive, so investing in an efficient hull makes a lot of sense when it reduces the capital cost and weight of the power train. It's a realistic hull for many of our customers. We've also tested our system on a 15' rigid inflatable (RIB), and it worked very well.

APPLICATION
It's a great motor for regular use, and for low to moderate range. As some pointed out, lakes are great, because there is a well-known limit to how far you'd need to go. This is not the best motor for going long distances infrequently (unless you place a very high premium on quiet operation or zero emissions, such as on bodies of water that prohibit internal combustion engines). For those who nearly always run at low to moderate range, but have to go a long distance once a year, it might be worth switching to a gas outboard for that one outing, and keeping the vast majority of outings quiet and clean.

Daily boaters who use outboards often experience hearing loss. Rowing coaches, for example, experience very high rates of hearing loss due to prolonged exposure to outboard motor noise over a number of years. Some tell us they've lost 20-50% of their hearing. They crave a system that will allow them to be on the water every day and focus on what they do, without losing their hearing in the process.

This is not for every application, but for some, it will be just right. As batteries improve (about 7% improvement per year in energy density and cost), the range of appropriate applications will grow.

PRICE
We have not announced a price; however, we have said our battery packs should cost around $1/Wh (about the same cost per Wh as the Torqeedo battery pack), and that our outboard should cost a little more than a conventional gas outboard (which means more, but less than double). I'm sorry I can't be more precise at this time.

PRE-ORDER
A few on this forum have remarked that they would not pre-order without knowing a final price. That's a valid point, and not everyone should pre-order. Like Tesla, we take pre-orders before we know the final cost of our production system. (Tesla took thousands of pre-orders for the Model S before announcing a price, and before having produced a volume car.) The deposits are fully refundable for any reason (or no reason). Pre-orders help us gauge volume, which is a key input into cost. We can get more conventional financing, and make more rational purchases of parts, when we have a good idea of volume. So with pre-orders, our costs are reduced, which allows us to sell a better product at a lower price.

Thanks!

Andy Rebele
Founder
Pure Watercraft
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post #77 of 84 Old 12-12-2015
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Re: Would anybody be interested in an electric outboard like this?

Quote:
Originally Posted by newhaul View Post
Volvo penta patented the duo prop in 1982 The benefits of Duoprop - DPS Duoprop : Volvo Penta so its not a new technology BT the patent may have run out allowing this company to finally use it.
The boat to which you're referring is an early (2012) learning project of ours in which we converted a Cobalt. The duo prop is indeed a Volvo Penta. Our outboard motor (which is our own product) does not use a dual prop; it uses a large diameter, low RPM (1500) prop.
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post #78 of 84 Old 12-12-2015
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Re: Would anybody be interested in an electric outboard like this?

Andy,

Thank you very much for joining us and correcting this. I really do think there is a market for what you are doing, and hope you guys have a lot of success. Quality electric installs at a reasonable price point are difficult to find.

I do have a couple of questions/comments for you however.

1) you may want to look into lifepo batteries as well. I appreciate you want the energy density of cobalt, but there are a lot of boaters who simply will not install the cobalt chemistry (I am one of them). The risk of fire is simply too high. I would be willing to trade maximum power density for eliminating the risk of thermal runaway.

2) voltages as high as you are using do not have approved standards in the marine industry. What star darts are you using to ensure safety?

3) has any consideration been given to a hybrid system? With a smaller, say 4kw generator acting as a range extended? How would this work with your chargers?

4) knowing the pre-order is fully refundable is critical and changes my view of the situation substantially.

Again, thank you for your time, and coming here to correct some poor information.

Greg
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post #79 of 84 Old 12-12-2015
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Re: Would anybody be interested in an electric outboard like this?

Quote:
Originally Posted by Stumble View Post
Andy,

Thank you very much for joining us and correcting this. I really do think there is a market for what you are doing, and hope you guys have a lot of success. Quality electric installs at a reasonable price point are difficult to find.

I do have a couple of questions/comments for you however.

1) you may want to look into lifepo batteries as well. I appreciate you want the energy density of cobalt, but there are a lot of boaters who simply will not install the cobalt chemistry (I am one of them). The risk of fire is simply too high. I would be willing to trade maximum power density for eliminating the risk of thermal runaway.

2) voltages as high as you are using do not have approved standards in the marine industry. What star darts are you using to ensure safety?

3) has any consideration been given to a hybrid system? With a smaller, say 4kw generator acting as a range extended? How would this work with your chargers?

4) knowing the pre-order is fully refundable is critical and changes my view of the situation substantially.

Again, thank you for your time, and coming here to correct some poor information.
LFP vs NMC
We've used LFP batteries before, too, and agree that it's the most stable chemistry; but as you said, the energy density of NMC is far superior (~50% higher). Tesla uses an even less stable (but very high energy density and low cost) chemistry, and even chooses cells that omit the internal fusing, but builds a well-engineered pack that makes the pack-level safety very high. We took the same general approach, investing in the engineering to make a safe, long-lasting, energy dense, cost-effective pack. We use 18650 form factor cells, so they're small, and the energy discharged by a single-cell failure is low. We also encase our cells in a phase-change material that can absorb the heat of a cell failure, without propagation to neighboring cells. This material also keeps our pack temperatures healthy for the cells, so we can take higher discharge rates than we could otherwise, while keeping cycle life on the higher end of the range. Our BMS monitors cell temperatures so that they remain safe, and we slow down discharge or shut down the pack if the temperatures ever exceed our standards. We encase our battery pack in an aluminum box that is IP67 rated, for safety in a marine environment. (You seem like you have enough experience to know that many vendors do much less than this.) In the end, I think it's safer to use NMC in a well-engineered pack than LFP in a hacked-together pack.

SAFETY
I think you meant "standards". We have CAN, low-voltage, and high-voltage lines between our outboard and battery packs. High-voltage connectors are kept open at all times unless there is affirmative communication (on the CAN line) that shows good battery pack health and good conditions on the outboard side.

HYBRID
Hybrids work well for cars because the power needs at top speed are much lower than during acceleration, so you can size the gas motor for the average power, and use a much smaller gas motor than you would need for a gas powered car of the same caliber. Boats use top power at top speed, so you'd need the same size motor as you'd need for a simple gas-powered boat (or you'd need to have restrictions on usage, like "don't go full power for longer than 10 minutes") The result in any case would be a very heavy power train, and weight is a bigger issue in boats than cars. There are certainly good applications where weight is not very important, but that's not our market. We add the most value where energy density and power density are desired.

And the motivations behind people who want our system often include that they boat on a restricted waterway, or they crave the silence of an electric system. It's really eye-opening when you boat fast with a nearly silent system. Even those who have seen videos and charts of our system are very surprised by the feeling when they have a test drive. I'm sure you'd feel the same way, and I'd invite you to come out with us any time you happen to be in the Seattle area, or we take our system through Louisiana.

Thanks for the thoughtful response.

Andy
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post #80 of 84 Old 12-13-2015
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Re: Would anybody be interested in an electric outboard like this?

First, thank you for taking the time to explain yourself and the product on here, after having been questioned. And without getting into any of the rest of it, I wanted to bring up this part:

Quote:
Originally Posted by PureWatercraft View Post
HULL
It's true that we use a low-wake, efficient hull for testing. Batteries are expensive, so investing in an efficient hull makes a lot of sense when it reduces the capital cost and weight of the power train. It's a realistic hull for many of our customers. We've also tested our system on a 15' rigid inflatable (RIB), and it worked very well.
While this may very well be true, the only thing I can say is that this being a sailing forum, it's understandably going to be a different boat, no pun intended. To play devil's advocate (and believe me, I know that MANY companies are the same, I'm not saying this directed at you and your company alone), but that's saying "We're going to use the method that gives us the ability to claim the best possible numbers that we can show, even if it means a drastic reduction if someone uses something else instead". Would be like saying I've made a gas motor that gives 1000 miles per gallon, with fine print saying it was achieved using a child's bicycle being ridden by a 40lb toddler going downhill with a tailwind.

I'm not taking away from the potential of your system, or the objective of the OP's goal of gathering opinions. However, it's obviously going to be something not nearly as well-received on a a forum where users are using displacement hulls weighing far more than your test rig, or ideal hull design to achieve the performance claimed. Once you start factoring that in, it's very likely to severely impact performance, and distance/range figures of the system, which is why many of us are questioning it's feasibility in our real-world examples. I do understand that it's not something that you may have immediate chances to test, but I know that for myself, unless I had something that I could compare apples-to-apples with something similar to what I'm using, it's one of those things where I say it's nice for people that are better suited for it, but there's just no way I could justify the expense with too much unknown for me.

Best of luck though, and perhaps we'll get a test soon that's more representative of our usage to gauge it by.

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