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Old 26-05-2016, 18:56   #1
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Once you've gone electric ....

Is there ever a real urge to go back to an IC engine ...?
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Old 26-05-2016, 19:57   #2
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Re: Once you've gone electric ....

Yes. Our friends switched from electric to internal combustion after about a year.


AFAIK most of the electric Lagoons are now diesel powered.
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Old 26-05-2016, 20:02   #3
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Re: Once you've gone electric ....

Depends on what you are doing...

You simply will not have the ability to go as far as fast with electric as is possible with gas or diesel.
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Old 26-05-2016, 20:34   #4
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Re: Once you've gone electric ....

Yes you can go back to diesel or (yock). Gasoline. Now the hard part what boat are you converting back to usable if engine?
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Old 26-05-2016, 20:40   #5
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Re: Once you've gone electric ....

Electric makes great sense for entering and exiting a marina.

It can't compete with the energy density of diesel for cruising. Electric also makes little sense at high latitudes.

We carry 165 gallons of diesel. I haven't done the math but the equivalent energy in batteries would be many times greater than our entire weight.

Its also difficult to keep large banks charged with solar arrays that will fit on a boat.

Sailing Uma are off cruising. They are electric and having fun. They have shown the simplicity of electric.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
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Old 26-05-2016, 20:44   #6
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Re: Once you've gone electric ....

I am still thinking/hoping that a hybrid could be the wave of the future with an engine like this to charge up the batteries/drive the motor, and that could run on diesel or cooking oil...Prototype
much more efficient use of fuel... Toyota has a prototype in the works too...
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Old 26-05-2016, 21:54   #7
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Re: Once you've gone electric ....

Quote:
Originally Posted by leftbrainstuff View Post
We carry 165 gallons of diesel. I haven't done the math but the equivalent energy in batteries would be many times greater than our entire weight.
Ooooh, math problems. I love them.

If my calculations are correct:
165 gallons of diesel will generate about 170,000 Amp hours @ 12V
(Based on a commonly accepted consumption rate of 0.06 gallons per hour per HP. 1HP = 745.7 Watts)

That is about 850 x 200Ah batteries.

Figure on about 160lbs per battery (LA - Lithium will be half that weight)
That's 136,000 lbs or 68 tons

Double that it you only want to take your LA batteries down to 50% SOC

Of course it would only be around 35 tons if you went with Lithium, and they would only cost you around $2 mllion at $2,500 each
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Old 26-05-2016, 22:34   #8
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Re: Once you've gone electric ....

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Ooooh, math problems. I love them.

If my calculations are correct:
165 gallons of diesel will generate about 170,000 Amp hours @ 12V
(Based on a commonly accepted consumption rate of 0.06 gallons per hour per HP. 1HP = 745.7 Watts)

That is about 850 x 200Ah batteries.

Figure on about 160lbs per battery (LA - Lithium will be half that weight)
That's 136,000 lbs or 68 tons

Double that it you only want to take your LA batteries down to 50% SOC

Of course it would only be around 35 tons if you went with Lithium, and they would only cost you around $2 mllion at $2,500 each
Ah, math...science... who needs 'em? Such downers.
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Old 26-05-2016, 22:38   #9
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Re: Once you've gone electric ....

Quote:
Originally Posted by Don C L View Post
I am still thinking/hoping that a hybrid could be the wave of the future with an engine like this to charge up the batteries/drive the motor, and that could run on diesel or cooking oil...Prototype
much more efficient use of fuel... Toyota has a prototype in the works too...
The problem with hybrid is the use case is far different from a car in city driving.

Car in city driving: Average speed maybe 35mph but needs strong bursts of power for 10-20seconds followed by modest power output for 60-120 seconds followed by zero power output waiting at the next light. Repeat this pattern over and over. A pure ICE can't maintain peak efficiency in all three conditions. A hybrid can set the ICE to generate power at the long term average and optimize it for peak efficiency. Then it can use the battery for those short bursts of power.

Cruising boat:
- If you just need to get in and out of the marina, you probably won't burn 5gal per year, so there is no savings to gain.
- If you do motor regularly, let's take a 5hr run...once you get up to cruising speed, you typically never touch the throttle until you reach your destination. Assuming the drivetrain is properly sized, the engine is already running right around peak efficiency. You don't have those peaks and valleys in power demand to take advantage of so you actually wind up losing efficiency because the conversion to electric and back to mechanical energy is not 100% efficient. At best you can match the pure ICE with a hybrid system but at additional cost.
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Old 26-05-2016, 22:51   #10
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Re: Once you've gone electric ....

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Originally Posted by valhalla360 View Post
The problem with hybrid is the use case is far different from a car in city driving.

Car in city driving: Average speed maybe 35mph but needs strong bursts of power for 10-20seconds followed by modest power output for 60-120 seconds followed by zero power output waiting at the next light. Repeat this pattern over and over. A pure ICE can't maintain peak efficiency in all three conditions. A hybrid can set the ICE to generate power at the long term average and optimize it for peak efficiency. Then it can use the battery for those short bursts of power.

Cruising boat:
- If you just need to get in and out of the marina, you probably won't burn 5gal per year, so there is no savings to gain.
- If you do motor regularly, let's take a 5hr run...once you get up to cruising speed, you typically never touch the throttle until you reach your destination. Assuming the drivetrain is properly sized, the engine is already running right around peak efficiency. You don't have those peaks and valleys in power demand to take advantage of so you actually wind up losing efficiency because the conversion to electric and back to mechanical energy is not 100% efficient. At best you can match the pure ICE with a hybrid system but at additional cost.
True, but I am thinking that the efficiency of that particular type of IC engine would make up for the difference. I am not considering a typical IC generator, no point in that. That's just a Rube Goldberg way of powering a boat, I agree. But maybe Stu, or you, can help me with the math of using that particular kind of engine with no crank shaft, valves, or drive shaft to generate only the Watts...
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Old 26-05-2016, 23:41   #11
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Re: Once you've gone electric ....

Quote:
Originally Posted by Don C L View Post
True, but I am thinking that the efficiency of that particular type of IC engine would make up for the difference. I am not considering a typical IC generator, no point in that. That's just a Rube Goldberg way of powering a boat, I agree. But maybe Stu, or you, can help me with the math of using that particular kind of engine with no crank shaft, valves, or drive shaft to generate only the Watts...
May as well say you will use food scraps in your Mister Fusion nuclear generator to power your boat.

If this prototype really is 30-40% more power per gallon of fuel, we will see them quickly take over. Since it's not a new idea, I'm not counting on it.
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Old 27-05-2016, 00:35   #12
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Re: Once you've gone electric ....

Quote:
Originally Posted by Don C L View Post
True, but I am thinking that the efficiency of that particular type of IC engine would make up for the difference. I am not considering a typical IC generator, no point in that. That's just a Rube Goldberg way of powering a boat, I agree. But maybe Stu, or you, can help me with the math of using that particular kind of engine with no crank shaft, valves, or drive shaft to generate only the Watts...

They claim "over 40% electrical efficiency". A diesel ICE generator is typically around 30%, so yes, if they bring it to market and it performs as claimed, you are looking at 30% fuel saving. But at this stage, they are very light on details.
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Old 27-05-2016, 00:47   #13
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Re: Once you've gone electric ....

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Originally Posted by StuM View Post
They claim "over 40% electrical efficiency". A diesel ICE generator is typically around 30%, so yes, if they bring it to market and it performs as claimed, you are looking at 30% fuel saving. But at this stage, they are very light on details.
Eh, I'm sure you're probably right. It just seemed like such a neat, simple, efficient way to make a generator that it had to be better.
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