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Announcing the Lean Green Machine Challenge

3K views 27 replies 12 participants last post by  braidmike 
#1 · (Edited)
Here's the throw-down on this hoe-down:

Build an electric propulsion system that works as well as, if not better, than my diesel engine.

Here's the low-down:

I have an aging Yanmar 1GM-10 engine powering my Georgian 23. I have a 10 gallon fuel tank. My engine puts out a raging 9 hp and 13 ft/lbs of torque. It burns 1/3 gallon/hour at cruise (3000 rpm) At that engine speed, it pushes my boat comfortably at hull speed (5.5 knots, roughly). Based on the numbers, under power I have a 30 hour range. Total weight of the propulsion package including full fuel tank is under 320 lbs. it also has an alternator which handles charging my starting battery and house battery. My slip is on an unserviced dock which means that shorepower charging is not an option so we are already running pretty lean and mean with our electrical usage. I don't have much room for a big solar array, although I am installing 30 watts worth of panels on my new davits. because this is a small cruiser, there is not a lot of spare space aboard, so it's nice to have a compact propulsion system that hides under the cockpit sole.



Sadly, I need to freshen my engine this year. Compression is getting lowish, so I see new rings and a freshened head in my future. Likely gonna cost me about $1000 and a weekend of my time (I do my own wrenching.) I am contemplating whether it makes more sense to pull the engine out and install a new one, which would be in the $5k range.

So, the discussion about electric propulsion got me thinking...


If a new engine would set me back $5k, then:

**I will offer $1000 to anyone who can build and demonstrate a reliable system that will do what my Yanmar does for the same money, weight and space. Furthermore I will BUY the system that meets the parameters outlined below:**

30 hour range at hull speed*. (*New! Revised! Proof that I really really want somebody to succeeed! The range requirement is now 50% LOWER!!!!!!!! 15, FIFTEEN, ONE FIVE hours!!)
Charging onboard electrical systems.
Total weight under 320 lbs.
Must fit under cockpit. 74" long x 24" wide x 20" high.
Total cost under $5000.


This is a small cruiser, 20' at waterline, displacing 4350 lbs.


So all of you inventors, dreamers, clean/green propulsion proponents, this is your change to convert me, and earn some cold hard cash at the same time.
 
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#2 ·
BL,

The 30-hour criteria is a bust. It's not going to happen, not even if you dropped the extra coin for Li4Pho batteries.

At the very least, it would take more space and more weight than your old system did by a considerable margin.

All other criteria are do-able.
 
#3 · (Edited)
I'd point out that the charging onboard electrical systems is also a bust... unless the system is a hybrid electric with some sort of fossil-fuel burning component... it will need a separate source to charge the system itself...

BTW, there's no way you'd get enough stored electricity to power the boat for 30 hours at cruising speed with a weight limit of 320 lbs. Just ain't gonna happen. Four T105 golf cart batteries are almost 300 lbs... and they only supply 450 amp-hours at 12 VDC.... or 225 @ 24 VDC, at a 20 hour discharge rate.
 
#6 ·
30 hour range at hull speed*. (*New! Revised! Proof that I really really want somebody to succeeed! The range requirement is now 50% LOWER!!!!!!!! 15, FIFTEEN, ONE FIVE hours!!)
Charging onboard electrical systems.
Total weight under 320 lbs.
Must fit under cockpit. 74" long x 24" wide x 20" high.
Total cost under $5000.
I'll build your system for $1G (maybe per day).

Remove two numbers, like the $!G total labour, and $5G total cost and you could have your drive train and a better boat in the process.

But clearly that was your point. An old POS gas engine is always going to be cheaper, hence the reason I use them.
 
#9 ·
Well sure, if we remove the total cost, then OF COURSE I could have a better boat, because money would be no object... but it is. I do not have an unlimited budget. Most sailors i know don't have an unlimited budget. Even Larry starts to hesitate writing cheques after the first 10 mill.

Where are you getting "POS gas engine" from? let's compare apples to apples- I wouldn't put a gas engine in, or take the hack approach of simply strapping a 9.9 hp longshaft outboard on the transom- THAT would be significantly cheaper and easier, but unsuitable.
 
#10 ·
To get us in the ballpark, I will assume that 5hp will push you to hull speed(this might be low depending on the boat) which is 3.7KW. To run 30 hours, you need to store 111kWhrs of electricity. The storage required for this would not come even close to your weight or space requirements. It is also way too big of a system to charge without an enormous solar array which is not possible in this case.

To recharge this, if you do it over 10 hours (this is quite a while if you can't charge at your own slip), you would be charging at 50A @ 220V not accounting for any inefficiencies. This is impractical so you would probably have to double the charge time.

If there is a solution to this, it is going to have to be out of the box. I am not a fan at all of hybrid electric propulsion systems for boats unless they are used to extend range in rare circumstances on a truly electric system. These systems are less efficient, have more stuff to go wrong, etc. The reason why hydrogen was hyped for so long is that it is a reasonable media in which to transfer energy quickly. Too bad it is not in the realm of practical for a project like this.
 
#12 ·
Hydrogen is actually a horrible fuel. The fuel in its natural state is far too volatile to use safely in most applications. To use it safely in an automotive or marine application, it would probably have to be converted to a metal hydride form. The problem with this is that the fuel is now much lower in energy density than it is in its natural form. Also, there is no way to quickly re-fuel a metal hydride cell short of swapping it out. To support swapping it out, you'd need to have a large infrastructure of stations that have the charged metal hydride cells available to swap.

Currently, the easiest and safest high-energy density fuel is liquid hydrocarbons-namely diesel or gasoline... this is why they are used in 99.9999% of the mobile transportation applications.

If there is a solution to this, it is going to have to be out of the box. I am not a fan at all of hybrid electric propulsion systems for boats unless they are used to extend range in rare circumstances on a truly electric system. These systems are less efficient, have more stuff to go wrong, etc. The reason why hydrogen was hyped for so long is that it is a reasonable media in which to transfer energy quickly. Too bad it is not in the realm of practical for a project like this.
 
#16 ·
Your answer is not a pure electric system, but rather a hybrid system. After all, you're willing to put up with running an engine while underway, so why not run a genset to power your electric motor.


Epod 2000 36Amp electric motor from re-e-power.com $2,750
Honda 2000i generator $1150
Xantrex 60C 60 amp charger $250
3x group 27 deep cycle batteries $300 (or less)
2.5gal gas can from gas station (with gas!) $10 Honda genset runs 15hr on 1.1gal of gas.

Total cost <$3000. Weight, is much MUCH less than your yanmar with tank and you get a high torque, quiet, reliable system. There is also some cool features such as the genset which you can use to charge your house bank (like your alternator). There is redundancy, so if your charger packs up you can still charge DC directly off the Honda. If the honda packs up you still have some range in the batteries themselves. Also, you now have 3 more 12v batteres which you can integrate into your house system if you so choose.

The re-e-power website appears to be not functioning to full capacity but rest assured that the motor is up to the task.

Medsailor

PS No need to send $1000. If you really like my suggestion or a variation thereof you could send me $100 and I would promise to squander it on wine, women and boats.... but not necessarily in that order.
 
#19 ·
Umm... 2750 + 1150 + 300 + 250 is a bit more than $3000 last I checked. Weight wise, this is also going to be more than the 320 lbs. of the Yanmar. The three batteries are probably close to 210 lbs. and the generator is probably another 100 and you haven't even gotten to the Xantrex or the Epod motor or fuel tank.

Your math sucks...:laugher :laugher

Your answer is not a pure electric system, but rather a hybrid system. After all, you're willing to put up with running an engine while underway, so why not run a genset to power your electric motor.

Epod 2000 36Amp electric motor from re-e-power.com $2,750
Honda 2000i generator $1150
Xantrex 60C 60 amp charger $250
3x group 27 deep cycle batteries $300 (or less)
2.5gal gas can from gas station (with gas!) $10 Honda genset runs 15hr on 1.1gal of gas.

Total cost <$3000. Weight, is much MUCH less than your yanmar with tank and you get a high t
 
#18 ·
Med, thanks for laying out the shopping list. That's the kind of thinking I like. There are a couple of stumbling blocks.
1) There is no way that the generator is going to be able to power the motor for 15 hours.
2) Fitting the batteries, controller, and generator into the available space.


Not perfect, but the best idea I have seen yet.
 
#22 · (Edited)
Med, even running full time, the generator's output would not keep up with the power demands of the motor. The 12 volt output is only 8 amps., less than 25% of the motor's rating, and the power still has to be stepped up to 36 volts. A generator any larger would definitely not fit in the available space.

I also have some concern with the re-e-power approach of hanging the motor in a pod under the hull. Unfortunately, it maybe a tough fit with my hull, and would present some structural issues.
 
#23 · (Edited)
BLJ, the direct DC output of the honda is indeed too small. That's the point of using the Xantrex charger and 3 x 12volt batteries is to use the full 120volt output of the genset and step it up to 36volts. If you don't like the outside EPOD approach there are some companies that use direct to your existing shaft type installs.

Another thought is that instead of using top shelf parts (like the honda and Xantrex) you could do the ghetto-DIY option as listed here:
Building your own generator.
You could still use a brand new honda OHV engine, a bomar high capacity alternator and a fancy regulator and you'd be doing everthing in DC voltage and come out cheaper than the original system I reccomended.

Another thought still is to use a DC power supply instead of the xantrex and the batteries.

MedSailor
 
#24 ·
As with the 3 million fuel savers "invented" for automotive use over the years, I ask the question: If a motor manufacturer could save 40% on the fuel consumption (as claimed by most fuelsaver inventors) they would slaughter the car market - it would be worth billions of $. But even with their annual $200m R&D budget, they can't come up with a working solution. So how does the inventor in his suburban garage do it? Well, in truth he doesn't - they're all scams.

It's the same with your challenge. If a wealthy yacht-builder with a substantial R&D budget could provide silent endless propulsion they would also slaughter the market.

But have they?

No.

Why not?

Because it can't be done with the technology available today.

Like I said in another thread - get over it - fix your diesel.
 
#25 ·
Omato, I am not looking to get out of rebuilding my diesel. My intention here was to see if there was a viable alternative, maybe prompt some backyard tinkerer/lurker here to come forward and say, "hey, here's what I did," start a dialogue a little more focused than the usual blue sky electric boat threads by presenting a specific problem, and an incentive to solve that problem.
 
#26 ·
Omato, I am not looking to get out of rebuilding my diesel. My intention here was to see if there was a viable alternative, maybe prompt some backyard tinkerer/lurker here to come forward and say, "hey, here's what I did," start a dialogue a little more focused than the usual blue sky electric boat threads by presenting a specific problem, and an incentive to solve that problem.
I suppose I should have put some smilies and stuff in my post to indicate that I'm not on the attack - just offering an opinion.

The reason why the other posts on this subject are of "blue sky" quality is that with the technology available now, that's all it can be.

And like I said - a tinkerer is not likely to achieve something that the best engineering genius in the world with an almost unlimited budget can't.

Like some earlier posts alluded to - putting the kind of tech required into a 24 foot boat is a contradiction in terms - you'd have to use the electric boat to tow the one you're travelling in because there wouldn't be enough space for you in the electric boat. :D (see, there's the smilie)
 
#27 ·
MedSailor,

The question that I have with the system that you outline is whether it meets the power output requirement. The batteries that you included have so little storage, it is essentially negligeable over 30 hours. That means that the generator needs to power the motor directly. The generator is rated at 2kw feeding a charger (~90% efficient), powering a motor controller (~95% efficient for a really good one) giving you power to the motor of 1.7kw to the motor best case scenario. This is 2.3hp which is very unlikely to push the OP's boat at hull speed. You might well get to 1/2 of hull speed in calm conditions but it doesn't meet the spec of maintaining hull speed. What you are proposing would most likely work if you went to a 4kw generator and the associated increase in charger size but this would significantly increase the cost and size of the system. Of the options posted, yours is the closest to meeting the specs but it still doesn't come close to meeting them in my book.

My issue with hybrids in boats is a separate issue. Their overall efficiency is lower because of all of the energy conversions and you really violate KISS. I have built 3 electric cars and 1 hybrid racecar and a hybrid is a real nightmare from the standpoint of what can go wrong. The reason that hybrids get better fuel economy in cars in the city is that they are parallel hybrids and the vehicle keeps accelerating and decelerating. In a boat, a parallel hybrid just doesn't make sense since we run constant rpm. The two applications are completely different (continuous versus intermittant).
 
#28 ·
FWIW:
I'm a pretty good tinkerer, and have an electric drive. My suggestion when you need to scale back on the requirements to match 2010's physical realities is to drop the requirement for hull speed. That's where you'll get the biggest bang for the buck. My system uses about 1.2KW to push the boat at 3kn in a calm protected harbor. Hull speed can be reached, but at a cost of 7.2KW. If my math is correct, that is a six fold increase. To do that for just a few minutes makes me weep for the batteries.
Sidenote: story on NPR the other day saying there will be a manufacturing glut for Lithium Ion batteries in 2012! Maybe by then the charging algorithms and systems can be marinized and come down in price, too.:laugher
Yeah, I'm not holding my breath...

And if someone does design the system your looking for, let me know! I'll buy stock in that one!:)
 
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