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Old 11-05-2014, 12:43 PM   #21
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Originally Posted by Ski in NC View Post
I think in both cars and boats there are some applications where electric and electric/hybrid makes sense. A boat doing picnic cruises can be charged with solar over several nice days of non use.

In my area, a typical day has over 50% of the electric supply coming from nuclear, most of the balance from natgas combined cycle where thermal efficiency bumps into 60%. Almost none from coal.

So in my area, a car for local trips charged off the grid really does work on many if not all levels. Folks are even running around in golf carts!! True that there are transport and conversion losses, but considering the efficiency of the suppy, these losses can be absorbed in the calc without taking it net negative.

For my boat and car, no way. Both are expected to make and do make long trips. Liquid fuel is the only practical way for these.
...set up properly and properly used hybrids can be great.

Like many systems.... such as split air or marine air in the other thread...either can be more efficient depending on variables....

But back to the OP...yes there are things called electric generators but they usually are getting power from somewhere and converting it...they are not usually storage units such as batteries.

The portable gasoline genset is you easiest option for now in my eyes.
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Old 11-05-2014, 12:53 PM   #22
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Originally Posted by Ski in NC View Post
I think in both cars and boats there are some applications where electric and electric/hybrid makes sense. A boat doing picnic cruises can be charged with solar over several nice days of non use.

In my area, a typical day has over 50% of the electric supply coming from nuclear, most of the balance from natgas combined cycle where thermal efficiency bumps into 60%. Almost none from coal.

So in my area, a car for local trips charged off the grid really does work on many if not all levels. Folks are even running around in golf carts!! True that there are transport and conversion losses, but considering the efficiency of the suppy, these losses can be absorbed in the calc without taking it net negative.

For my boat and car, no way. Both are expected to make and do make long trips. Liquid fuel is the only practical way for these.
If electricity came from nuclear (there are issues with this) solar, wind or hydroelectric), electric cars might make sense. In many parts of the country, electricity is generated by burning coal. This generates as much or more pollution as burning gasoline or diesel directly in vehicles. The advantage is, the pollution is far away in poor people's neighborhoods.

The one thing electric vehicles have that's efficient is regeneration from slowing down and braking. Instead of generating heat, braking generates electricity to recharge the batteries.

If electric cars were such a great idea, people would be buying them without government subsidies.
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Old 11-05-2014, 01:47 PM   #23
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A 2000 watt generator produces 2.6 hp under ideal conditions if you can move your boat with 2.6 hp go for it.
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Old 11-05-2014, 03:17 PM   #24
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My motor is the Elco motor w 6 deka 8D AGM glass matte wet cell batteries.

Here's the vision: I'm cruising in choppy swells & I'm 30 minutes away from my destination but my batteries are low cuz of rough seas. The portable generator will charge my batteries as I'm cruising to avoid running out of power before I can get to my destination. It's just an extra charge, just in case I run low.

If you're not too far into it... you might investigate a big bank of 6V deep cycle golf cart batteries, instead of 12V 8D batteries.

A single Lifeline 8D (for example) will give you approx. 255 Ah. A bank of 6 will give you approx. 1530 Ah. (Many manufacturers spec that at closer to 245 Ah for an 8D, or 1470 Ah for a bank of 6.)

A pair of 6V GCs will give you at least 220 Ah, but taller versions can get you to 300 or even 400 Ah per pair. You should be able to fit at least 6 pairs of GCs in the same space as 6 8Ds... so with taller GCs you could get to 1800 or 2400 Ah in the same footprint.

Two additional advantages: each individual 6V battery weighs less than an 8D, so you can dispense with some of the labor (maybe one less hulk, and you won't need the mule and the small boy)... and golf cart batteries are a true deep cycle design, unlike many of the 8Ds (although I think the Lifeline 8Ds are spec'd as "deep cycle").

Check here for comparisons: Lifeline Batteries - Marine & RV Deep Cycle Batteries

The golf cart batteries are the GPL-4CT (220 Ah/pair), 6CT (300 Ah), and L16T (400 Ah).

The portable generator is a fair enough idea, although as far as I know the only manageable portable products -- for your purposes -- are like the small Honda and Yamaha gasoline models. (Refilling a small-ish gasoline tank while sloshing around in rough seas could be an issue... There is a way to run these on propane, should that interest you.)

Anyway, they convert energy from gas to electricity. Unlike a battery pack as used for emergency auto starting; those simply bring some additional pre-stored electricity to the scene.

You may eventually want some solar, but probably can't get enough energy from that fast enough to make much difference in your "choppy seas" scenario. Might be very nice for recharging batteries at anchor, though.

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Old 11-05-2014, 03:27 PM   #25
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Maybe you can get some ideas from these guys: Duffy Electric Boat Company - America's Electric Boat Since 1970
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Old 11-05-2014, 04:17 PM   #26
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yes and no. A portable gasoline generator such a Honda 2000 inverter series and a large capacity charger may work. An electric powered electric generator won't work unless you have a really long extension cord!
If you are going to plug anything in, plug in a charger. That's what they are made for.
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Old 11-05-2014, 04:24 PM   #27
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Not so fast. I saw and worked around one of those many, many years ago.

It was part of an uninterruptable power supply for a large main frame computer system. This was back in the 1970s or so before much of the technology we take for granted today was available.

There was an electric motor turning a generator and a large heavy flywheel. There was also a natural gas powered engine connected through a clutch. The mainframe was powered by the generator's output 24/7, not the power coming into the campus.

The way this worked was,, if the power went out, the inertia of the flywheel kept the generator spinning long enough for the engine to start and reach speed. At that point the clutch would engage and the generator would continue running powered by the gas engine. A power glitch would shut down the computer system and that was a big deal.

Why was I there? The system was in a dedicated brick building and was overheating. Some dufus took a brick saw and cut a window into the wall without covering the smoke detector. The smoke detector mistook the brick dust for smoke and shut the entire system down and emptied the building as well. One part of my job was repairing fire alarm systems.

True, this wasn't efficient energy wise but it's the best they could do at the time.
Yes, I didn't say it couldn't be done, and what you describe is a valid though crude by today's standards, way to bridge a power transition.

My point is that the electric power going into the motor/generator will always be less than the power coming out. So using batteries to power the motor and the attached generator to charge the batteries is a losing proposition. Operating such a device will drain the batteries fast than leaving it turned off.

Now I might be misunderstanding what the OP was contemplating, so my comments may not be relevant.
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Old 11-05-2014, 05:07 PM   #28
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Sorry I am late to this fascinating discussion.

So the OP has six 8D AGMs (so that is approximately 1500 amp hours at 12V) and he discharges them in 4 hours during normal operation. He wants a back up system to extend his time if he gets in trouble. Sounds like the Chevy Volt or similar.

So he needs a power source that will put at least the power draw of his motor back in, which is presumably 1/4 of 1500 or about 375 amps which at 12 V is 4,500 watts. That is a good sized generator. Or he could just start a smaller generator, say 1,500 watts when he leaves the dock and after 3 hours that would have put enough energy in the battery bank to run for another hour. But that kind of defeats the point of an electric boat, doesn't it.

A permanently installed diesel generator of that size is going to cost $10 to $15,000 so that is probably out.

He could gang up two Honda or Yamaha 3,000 watt EU generators and make it. These will cost about $3-4,000. And it will probably take a 400 amp DC charger to go with either generator scheme at a couple of grand.

So what does he want to do? Start and run the generator from the moment he leaves the dock? Or does he want to just replace the battery power when it poops out 30 minutes from the dock. Does he want permanently installed diesel at $15,000 or does he want a couple of portable Hondas at $4,000.

Those are the choices it seems. And that is the nature of electric propulsion. It works fine for carefully selected mission profiles. But when something goes wrong, unless you have a fully installed internal combustion backup system like the Volt, you are in trouble.

My advice is to pick your days and mission profile on the water carefully, so you can make it home on the internal batteries only. Enjoy the peace and quiet when you go because you aren't going to like the expense or the noise of an "electric generator".

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Old 11-05-2014, 06:34 PM   #29
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My point is that the electric power going into the motor/generator will always be less than the power coming out. So using batteries to power the motor and the attached generator to charge the batteries is a losing proposition. Operating such a device will drain the batteries fast than leaving it turned off.
Oops, said it backwards. I meant that the power going in is always MORE than the power coming out, i.e. the hypothetical generator would consume more power than it produces.
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Old 11-05-2014, 08:31 PM   #30
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If you are trying to explain why the perpetual motion machine wont work you need a new audience. Electric driven conveyance is a nice novelty but until we get the super conductor perfected its just not practical. Energy storage and replenishment is not even close to what is required. As of now, on boats anyway, direct drive diesel is the most efficient.
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Old 11-05-2014, 11:01 PM   #31
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Thanks for all of this information and for such a good discussion!

I wanted to address some of the questions, just for clarification.

FYI, the motor I'm installing is the Elco EP-1200 (12 h.p., up to 7 hours range, 33 nm, 106 amps) - and I already mentioned I'm installing 6 batteries, which Elco and my yard agree will give me ample range and power. (My boat's 27' and this motor has specs to 35'). For more info, check out Elco's website (search "Elco electric motor" and you'll get their site & technical specs).

That said, solar panels are NOT recommended because it won't be able to charge sufficiently if I do get into trouble.

My yard is recommending going with the gas generator, and I think I'll take that advice for now. I like the idea of an electric generator, but I think after reading everyone's comments here, the gas generator would be the most reliable.

Regarding adding more batteries, it's being discussed. My funds are tight with the conversion, so if I go with more batteries, it will have to be done later. My fuel tank would need to be removed to accomodate the extra batteries, and that's a big cost...

A large part of this will be trial and error. I will have a panel that will keep me informed of my range, but I was really just concerned about choppy seas and getting stuck in the middle of the Chesapeake Bay without a marina around. The good news is that I am a small picnic boat and will mostly hug the shoreline, so I don't expect to run into problems -- but we all know that things happen out there, so the gas generator is probably the best back-up.

Next season, I'll be able to test the performance of this motor. That's the real issue -- no one knows, but next summer, I suspect I'll know what there is to know about the conversion and can then adjust my power needs after I've gained the experience.

Meanwhile, thanks for this discussion! I learned a lot and just by reading everyone's comments and concerns, it seems like the gas generator is the best choice. Next season, though, I should be an expert on this...
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Old 11-06-2014, 06:34 AM   #32
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Thanks for all of this information and for such a good discussion!

I wanted to address some of the questions, just for clarification.

FYI, the motor I'm installing is the Elco EP-1200 (12 h.p., up to 7 hours range, 33 nm, 106 amps) - and I already mentioned I'm installing 6 batteries, which Elco and my yard agree will give me ample range and power. (My boat's 27' and this motor has specs to 35'). For more info, check out Elco's website (search "Elco electric motor" and you'll get their site & technical specs).

That said, solar panels are NOT recommended because it won't be able to charge sufficiently if I do get into trouble.

My yard is recommending going with the gas generator, and I think I'll take that advice for now. I like the idea of an electric generator, but I think after reading everyone's comments here, the gas generator would be the most reliable.

Regarding adding more batteries, it's being discussed. My funds are tight with the conversion, so if I go with more batteries, it will have to be done later. My fuel tank would need to be removed to accomodate the extra batteries, and that's a big cost...

A large part of this will be trial and error. I will have a panel that will keep me informed of my range, but I was really just concerned about choppy seas and getting stuck in the middle of the Chesapeake Bay without a marina around. The good news is that I am a small picnic boat and will mostly hug the shoreline, so I don't expect to run into problems -- but we all know that things happen out there, so the gas generator is probably the best back-up.

Next season, I'll be able to test the performance of this motor. That's the real issue -- no one knows, but next summer, I suspect I'll know what there is to know about the conversion and can then adjust my power needs after I've gained the experience.

Meanwhile, thanks for this discussion! I learned a lot and just by reading everyone's comments and concerns, it seems like the gas generator is the best choice. Next season, though, I should be an expert on this...
l would also make sure I was a member of Sea Tow or BoatUS......
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Old 11-06-2014, 06:54 AM   #33
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Certainly interested in how you project works out. Given what your intended use is, who knows it may be the perfect fit. I looked very seriously into this when I owned a 40 foot sailboat. It would work for that because under sail you were regenerating to charge the batteries. DC Gen to run the house with a large inverter. The gen would run the engine without pulling from the batteries if you needed to do that. Numerous examples of this working on sailboats. Since you can't use the regeneration in the MY it may be more of a challenge. Please keep us informed on how it goes.
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Old 11-06-2014, 08:02 AM   #34
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Even though it may be ugly, maybe a simple backup outboard? A 10hp is still somewhat managable by yourself. A small above deck fuel tank and a transom mount to drop it in the water when you need it.
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Old 11-06-2014, 08:41 AM   #35
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Is that 106 Amps going to be at more than 12V ???
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Old 11-06-2014, 08:50 AM   #36
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............. I like the idea of an electric generator, .............
Please - What do you mean when you speak of an "electric generator"?
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Old 11-06-2014, 08:53 AM   #37
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l would also make sure I was a member of Sea Tow or BoatUS......
Yes, so they can bring you a couple jugs of electricity when you run out.

Seriously, I would recommend a towing membership for anyone boating on anything bigger than a farm pond. Regardless of the means of propulsion.
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Old 11-06-2014, 10:30 AM   #38
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Starside:

Your latest post has me really confused. In my earlier post I deduced from your first post that you have a 4,500 watt motor (375 amps at 12V) which is about 6 theoretical horsepower which seems about right to push a small boat around the harbor.

Your latest post says that you have a 12 hp motor that pulls 106 amps.

May I make a suggestion. Before you finish your design, beg or borrow a similar size boat with a small outboard on it, about 3 hp. See how fast the outboard pushes your boat at wide open throttle. If that works then use 3 hp for your design or more or less depending how the boat drives.

You can still use your 12 hp motor if that is what you have, but you need a control system to limit it to 3 or whatever hp works. Then figure that the motor is about 75% efficient and figure the amperage draw and therefore the battery capacity you need to cruise for 4 hours. You may be surprised.

BTW this is a straightforward electrical engineering exercise. If the boatyard guys advising you do not have that kind of knowledge, find someone who does.

David

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Old 11-06-2014, 11:10 AM   #39
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Hi DJ, the Elco EP-1200 is what was recommended for my boat by Elco & my yard, so I have to assume it's the right engine. They assure me I'll have ample range at 6-7 knots for 4 hours.

I'm not an electrician so I don't know the tech stuff, but this project has a lot of yard crew on hand, including electricians, engineers, carpenters etc.

As the owner & a lay person, it could be Im not relaying the info correctly but Elco has a good website if you want to review the specs. I personally am trusting the experts. Elco has done these conversions before, so I'm following their lead. My yard is also a fine crew & I trust their advice.
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Old 11-06-2014, 11:15 AM   #40
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Skinny, an outboard is a good idea but it may not work cosmetically. One reason I got an antique is for her beauty but they do make small electric engines that are sleek - just not sure re powerful enough but it gives me more options.
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