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Old 11-05-2014, 10:01 AM   #1
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Electric generator/charger?

Is there such a thing as an electric generator?

I'm converting my Elco to an electric motor but my range is 4 hours under perfect conditions, so I'm hoping to get a generator for extended trips.

That said, my yard is recommending a portable gas generator that can be hauled around but I'm just wondering if there's a portable electric one.

I think with the constant innovation w these electric motors that maybe there is an electric generator out there so thought I'd ask.

Does anyone have experience with this?
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Old 11-05-2014, 10:11 AM   #2
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If you mean a generator powered by an electric motor, the answer is no since it fundamentally violates the laws of conservation of energy (those are laws of physics, not human behavior laws).

The issue is that the amount of electricity that goes into such a generator to run it is more than the electricity that you get out, so all the device does is waste energy.

If I understand your boat setup, you have an electric boat that runs off batteries, correct? This theoretical electric powered generator would also run off the batteries, and return generated power to the batteries, right? But since it takes more power to run the generator than it produces, it would just drain your batteries faster, not charge them.
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Old 11-05-2014, 10:22 AM   #3
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I was thinking a portable generator, one that I charge before the trip so if my batteries are running low during the trip, I can charge her enroute. That's what the portable gas generator is used for.

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.

Does that make sense?
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Old 11-05-2014, 10:32 AM   #4
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I was looking at a boat on Yachtworld the other day that had an electric wing engine that could be powered by a diesel generator when the batteries started running low. I can't remember the boat but I think it was a Nordhavn. The question I had was how efficient that setup was versus a diesel wing engine.
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Old 11-05-2014, 10:38 AM   #5
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Yeah, I need to do some research. I like the idea of something portable but I want it to be small & not too heavy for me to lug around. :-) I thought an electric generator would be smaller but I'm not sure they make it yet. The electric motors in boats are still rather new, I think. Cars are more advanced -I think Tesla may have a portable charger, now that I think about it...

I need to do more research...
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Old 11-05-2014, 10:39 AM   #6
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Quote:
Originally Posted by Starside View Post
I was thinking a portable generator, one that I charge before the trip so if my batteries are running low during the trip, I can charge her enroute. That's what the portable gas generator is used for.

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.

Does that make sense?

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!
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Old 11-05-2014, 10:41 AM   #7
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I think you are trying to take a very simple approach to a hybrid propulsion system...totally dig it.

Do you have any specs on the motor and current draw while cruising?

I think realistically you are either going to supplement your cruise range by adding power through some means (solar, gas generator) or put on a small outboard in case something bad happens like you run out of charge.

If you know what you draw or power under cruise, a generator of equal size will let you run as long as you feed the thing gasoline. Something smaller will extend your range but eventually you run out of steam or have to stop propulsion and wait for your batts to charge up again.

You would probably be better off with a DC generator and not some off the shelf Home Depot generator. You'll lose effeciency going from AC to DC. Depending on your needs, maybe a used marine diesel genset would do the trick.
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Old 11-05-2014, 10:41 AM   #8
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Too funny, Highwire! I better research this some more.
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Old 11-05-2014, 10:45 AM   #9
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If you mean a generator powered by an electric motor, the answer is no since it fundamentally violates the laws of conservation of energy.
Nonsense! You've been reading too much of this website

"Power Companies Hate This!" = Scam
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Old 11-05-2014, 10:46 AM   #10
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Thanks Skinny.
Let me look at the specs on the motor & I'll get back to you here. It's a complicated system but I do think a portable generator is needed for added range. I'll also ask my yard for the name of the rec generator. That may give us a direction.

Later...
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Old 11-05-2014, 11:01 AM   #11
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If you mean a generator powered by an electric motor, the answer is no since it fundamentally violates the laws of conservation of energy (those are laws of physics, not human behavior laws)..........
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.
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Old 11-05-2014, 11:02 AM   #12
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All "generators" and alternators produce alternating current. So called D.C. generators just change it inhouse. You could do as well with an efficiently sized diesel gen and the biggest charger it can handle. What you are really looking for is a "jump box" type of unit, which would be a carry on battery of some type that you charge at home or at the dock. How about making your battery bank bigger and just holding some in reserve, not used until needed.
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Old 11-05-2014, 11:04 AM   #13
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I was thinking a portable generator, one that I charge before the trip so if my batteries are running low during the trip, I can charge her enroute.
You just described a battery pack or a battery. Battery packs are available but not big enough for you purpose. They're good for jump-starting engines.
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Old 11-05-2014, 11:14 AM   #14
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All "generators" and alternators produce alternating current. So called D.C. generators just change it inhouse.
Agreed, I was getting to the point of an off the shelf generator will need a battery charger to go with it. I'm assuming a wattage loss depending on how nice the charger is plus the weight, expense, wiring, etc. of having to buy another component.

How low buck are you planning on keeping this? Are we talking lawn mower engine turning a junkyard car alternator?
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Old 11-05-2014, 11:18 AM   #15
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You just described a battery pack or a battery. Battery packs are available but not big enough for you purpose. They're good for jump-starting engines.
That's what is sounds like. There's no difference between that and just installing more batteries in the first place. Actually, installing more batteries in the first place is better because the can be installed close to the motor and with larger cables to reduce loss.

Designing an electrical powered boat (not a dinghy, a relatively large boat) is pretty complicated and not for the person without a lot of knowledge about electric motors, batteries and charging systems. There are only a few on the market and the results aren't in yet.

One big problem with electric power is, when you run out of electricity you can't just call Sea Tow or TowBoatUS and ask them to bring you a jug of it like you can with gas or diesel.

Another problem - you can fill a gas or diesel tank in just a few minutes and be on your way. Recharging a large battery bank will take hours.
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Old 11-05-2014, 11:25 AM   #16
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Starside- the only energy storage system that is going to give you the "energy density" necessary to propel a boat at considerable distance is going to be a liquid fuel such as diesel or gasoline. Nothing else that you can carry will do the job. The equivalent energy stored in a battery involves something many many times heavier.

So you need either a gas or diesel genset. Charge the batts on longer trips. Preferably the genset kW rating should be slightly higher than the kW draw of the motor and other systems. You need to decide whether you want something permanently installed or something portable. Solar can help, but cannot provide the kW needed for continuous operation.

And take solace that you are not the only one in Washington, DC that needs some help understanding energy systems!! There are apparently many more up there that need some help in this regard.
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Old 11-05-2014, 11:29 AM   #17
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Fun topic, good luck with your project. Is what you are looking for a Dynamo? Fun reading: Dynamo - Wikipedia, the free encyclopedia
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Old 11-05-2014, 11:32 AM   #18
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Out of curiosity, have you considered adding solar panels?
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Old 11-05-2014, 11:35 AM   #19
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Starside- the only energy storage system that is going to give you the "energy density" necessary to propel a boat at considerable distance is going to be a liquid fuel such as diesel or gasoline. Nothing else that you can carry will do the job. The equivalent energy stored in a battery involves something many many times heavier.

So you need either a gas or diesel genset. Charge the batts on longer trips. Preferably the genset kW rating should be slightly higher than the kW draw of the motor and other systems. You need to decide whether you want something permanently installed or something portable. Solar can help, but cannot provide the kW needed for continuous operation.
And now you've introduced the inefficiencies of converting a diesel or gas engine's rotation to electricity, storing it in a battery bank and then converting it to rotation again, this time with an electric motor. It's more efficient to eliminate the batteries and electric motor and just connect the engine to the prop directly (through a transmission of course). Of wait, we've just "invented" a normal boat.

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And take solace that you are not the only one in Washington, DC that needs some help understanding energy systems!! There are apparently many more up there that need some help in this regard.
Agreed! Burn coal to make heat to make steam to turn a turbine to make electricity, transport it long distances, convert it to DC, store it in a battery, then use it to turn a motor to power a vehicle vs. burn gasoline or diesel to produce rotation to power the vehicle directly. Which is more efficient?
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Old 11-05-2014, 12:41 PM   #20
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And now you've introduced the inefficiencies of converting a diesel or gas engine's rotation to electricity, storing it in a battery bank and then converting it to rotation again, this time with an electric motor. It's more efficient to eliminate the batteries and electric motor and just connect the engine to the prop directly (through a transmission of course). Of wait, we've just "invented" a normal boat.

Agreed! Burn coal to make heat to make steam to turn a turbine to make electricity, transport it long distances, convert it to DC, store it in a battery, then use it to turn a motor to power a vehicle vs. burn gasoline or diesel to produce rotation to power the vehicle directly. Which is more efficient?
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.
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