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Old 18-10-2013, 08:44   #76
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Re: Longest time/distance you've had to motor?

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Originally Posted by bryguy67 View Post
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On ocean passages we will have a longer range when under power than a cat with only diesels as our battery bank will be refilled while motoring under diesel power allowing us to shut it off and power under electric again....then repeat the cycle.
...
This seems problematic. I think you will burn more excess diesel charging the batteries (and then using the batteries to power the electric drives), than you would use to just motor under diesel power. Unless of course your prop is not well-matched to your engine? Battery charging doesn't come for free.
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Old 18-10-2013, 08:48   #77
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This seems problematic. I think you will burn more excess diesel charging the batteries (and then using the batteries to power the electric drives), than you would use to just motor under diesel power. Unless of course your prop is not well-matched to your engine? Battery charging doesn't come for free.
Not all the energy created by a Diesel engine is converted into propulsion. I would assume the excess energy is captured and stored, like hybrid cars.
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Old 18-10-2013, 15:23   #78
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Re: Longest time/distance you've had to motor?

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Originally Posted by Paul Elliott View Post
This seems problematic. I think you will burn more excess diesel charging the batteries (and then using the batteries to power the electric drives), than you would use to just motor under diesel power. Unless of course your prop is not well-matched to your engine? Battery charging doesn't come for free.
Yep, that electric power has to come from somewhere. And there ARE losses.
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Old 18-10-2013, 15:24   #79
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Re: Longest time/distance you've had to motor?

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Not all the energy created by a Diesel engine is converted into propulsion. I would assume the excess energy is captured and stored, like hybrid cars.
It's about time somebody started capturing and storing those hybrid cars!
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Old 18-10-2013, 15:37   #80
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Re: Longest time/distance you've had to motor?

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Originally Posted by Paul Elliott View Post
This seems problematic. I think you will burn more excess diesel charging the batteries (and then using the batteries to power the electric drives), than you would use to just motor under diesel power. Unless of course your prop is not well-matched to your engine? Battery charging doesn't come for free.
A guy buys a half-million dollar catamaran and you are concerned he might use an extra $100 of diesel fuel so he can motor quietly when he wants to,
like maybe when the crew is sleeping and doesn't want to hear 'thump-thump-thump-thump'.

Charging the batteries to run your radio and autopilot, you know that takes more diesel than just motoring...

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Old 19-10-2013, 02:05   #81
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Storing the energy will be the major issue. And the cost (if it matters to you). Batteries are so much heavier than tanks, and they do not get lighter as you empty them either ...


It seems the set up you want (solar aided diesel drive) will be perfect in a cat. You can use a Vetus electric drives in between the props and the diesel engines and thus be able to use a cross-linked either-or drive on each hull.

Now diesel fuel cells are just behind the bend and they may be the next big thing. I have read they are 3x more efficient than a diesel combustion engine.

b.
So, why not use capacitor banks, as they are lighter and smaller, recharge and discharge rate is better...
Heavy discharge and frequency of recharge are higher. "Longer Service Life." Just sayin...
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Old 19-10-2013, 04:23   #82
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6 days (only 700 miles, bringing the boat from St augustine to north of Tampa not.once was the wind in our favor
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Old 19-10-2013, 04:40   #83
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6 days (only during daylight though)700 miles, bringing the boat from St augustine to north of Tampa not.once was the wind in our favor and several times we had 1-2 knots of current against us. It would have been near impossible in an electric boat without recharging via a generator
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Old 19-10-2013, 07:11   #84
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Re: Longest time/distance you've had to motor?

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So, why not use capacitor banks, as they are lighter and smaller, recharge and discharge rate is better...
Heavy discharge and frequency of recharge are higher. "Longer Service Life." Just sayin...
Link to any commercially available ones that could be employed in our aspect?

b.
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Old 19-10-2013, 07:35   #85
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Re: Longest time/distance you've had to motor?

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Originally Posted by lonesoldier0408 View Post
So, why not use capacitor banks, as they are lighter and smaller, recharge and discharge rate is better...
For a given volume, a typical battery can store as much as several hundred times as much energy as can a capacitor.
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Old 19-10-2013, 08:04   #86
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Link to any commercially available ones that could be employed in our aspect?

b.
I've only seen thier use in starting cars. However, the wieght savings are great... It's on youtube.com...
It may require additional power management electronics, but again, it would take a lot of that to eat up the gains achieved in wieght lost and amp out put...
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Old 19-10-2013, 08:32   #87
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Re: Longest time/distance you've had to motor?

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Not all the energy created by a Diesel engine is converted into propulsion. I would assume the excess energy is captured and stored, like hybrid cars.
The batteries in a hybrid car are charged via braking, not the engine though.
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Old 19-10-2013, 11:10   #88
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Re: Longest time/distance you've had to motor?

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For a given volume, a typical battery can store as much as several hundred times as much energy as can a capacitor.
Yep, and Super/Ultra Caps are very very expensive. But they have massive POWER vs capacity compared to a battery. Power == high rate discharge.
So they do have potential for a hybrid battery system, where you can use high-density storage batteries with high power caps. For example, the ZInc-air batteries have 4x capacity over lithium, but little power, i.e. they can dribble it out only slowly. Same goes for diesel fuel cells, they can't produce high power, but have very high capacity.
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Old 19-10-2013, 14:23   #89
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This seems problematic. I think you will burn more excess diesel charging the batteries (and then using the batteries to power the electric drives), than you would use to just motor under diesel power. Unless of course your prop is not well-matched to your engine? Battery charging doesn't come for free.
Perhaps you misunderstood. If I'm already propelling the boat under diesel power its not costing me more to load up the diesel with the duty of charging the batteries at the same time. The electric motor that is tied in to the diesel acts as a generator as well (picture your alternator on steroids). Once the batteries are full I can power under electric alone and I'm confident that diesel engines use less power when turned off :-)
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Old 19-10-2013, 14:40   #90
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Re: Longest time/distance you've had to motor?

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Perhaps you misunderstood. If I'm already propelling the boat under diesel power its not costing me more to load up the diesel with the duty of charging the batteries at the same time.
Incorrect.
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