Hi you guys,
I appreciate all of the energy you have expended during this process of my education. I get what you are saying about net benefit being zero. No configuration of pulleys or type of alternator/generator will generate enough juice to warrant the expense. It would be better spent on solar panels, or wind, right?
William A. Garrison
--- On Thu, 2/10/11, GNHBus@aol.com <GNHBus@aol.com> wrote:
From: GNHBus@aol.com <GNHBus@aol.com>
Subject: Re: [Electric Boats] Cruising with EP
To: electricboats@yahoogroups.com
Date: Thursday, February 10, 2011, 1:07 PM
sure thing, thanks for the input, ending note, from the internet, another rule of thumb It takes power to make power, and for every 25 amps that an alternator produces, it saps about one horsepower from the engine to drive it., In a message dated 2/10/2011 2:43:41 P.M. Eastern Standard Time, matwete@comcast.net writes: "Have you seen a picture/diagram of the concept ? The Propeller & Alternator are both turned by the electric motor. The motor will need "X" from the Battery while rotating both, for "Y" Time. The Alternator cannot put "X" back, but perhaps a portion of "X", to be supported by solar also maybe".
I haven't seen a picture offered here. But trust me, I've seen plenty of golf carts and I get the picture completely. Key words to understand here are yours "perhaps a portion" of the energy delivered can be returned to the battery. It's exactly as I noted earlier—you will be lucky if the overall efficiency from power OUT of battery to power IN to the battery is 50% or better.
"So, if both the propeller & alternator on the same shaft, are both turned by an electric motor,(at 3600 rpm?) will the alternator put any energy back to extend the range of the battery?"
Yes, but it's pointless. The net effect is to consume more, not less energy in doing so. How about some numbers as a hypothetical, eh?
First case---holding Power OUT as constant:
Batt Power Out Generated Power Power for Propulsion Speed Economy 4kw 0kw 4kw 5 n-mi/hr 1.25 n-mi/kwh 4kw 0.5kw 3kw 4.5 1.12 4kw 1kw 2kw 4 1.0 4kw 1.5kw 1kw 3 0.75 4kw 2kw 0kw 0 0.0
Second case---holding Speed Constant:
Batt Power Out Generated Power Power for Propulsion Speed Economy 4kw 0kw 4kw 5 n-mi/hr 1.25 n-mi/kwh 5kw 0.5kw 4kw 5 1.0 6kw 1kw 4kw 5 0.84 7kw 1.5kw 4kw 5 0.72 8kw 2kw 4kw 5 0.63
In either case above, SURE, you can see that you can generate power and send it back to the batteries. But in either case, look at the economy---as soon as you start doing this, the economy suffers badly. Even if you were able to develop and demonstrate a 99.9% efficient generator, a 100% efficient drivetrain and a 99.9% efficient motor/controller, you still lose power by doing this. It only makes sense for those who have some external energy regen source---either wind-, water-, or a steam or ICE engine.
Please, email me offline if this doesn't make sense to you--- let's end this thread.
-Myles Twete, Portland, Or.
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of GNHBus@aol.com
Sent: Thursday, February 10, 2011 11:06 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Cruising with EP I never suggested anyone spend any money on anything, I find it important for people that have ideas to understand the idea, where it works, and where it doesn't. Understanding comes from asking questions, more importantly not being afraid to ask a question. Have you seen a picture/diagram of the concept ? The Propeller & Alternator are both turned by the electric motor. The motor will need "X" from the Battery while rotating both, for "Y" Time. The Alternator can not put "X" back, but perhaps a portion of "X", to be supported by solar also maybe. It was understood to be a propulsion & regen situation, and as many people may think when first thinking, it could be possible to create a never ending loop of energy, (perpetual energy)BUT, as you have pointed out, there are inefficiencies that need to be understood that leads to a degenerating circumstance, or no free lunch as they say. So, if both the propeller & alternator on the same shaft, are both turned by an electric motor,(at 3600 rpm?) will the alternator put any energy back to extend the range of the battery? I believe that was the original intent. In a message dated 2/10/2011 1:32:23 P.M. Eastern Standard Time, matwete@comcast.net writes: My brain is melting…on one hand you indicated that you thought the other gentleman was getting our message and at the same time you posted comments and suggestions that would help him waste his money and shoot himself in the foot by adding a useless generator. This isn't a regen situation and so these suggestions don't help. But you're right---we need to teach folks "how to fish". And that's what I tried to do with my last post on the futility of doing what you are suggesting now. Let's look at your numbers in the hypothetical: · 400ah battery bank · 200amps being drawn from it · 100amps being delivered back to the bank from a high output alternator Q: "will it extend the capacity of the battery and range of the boat" A: No. Explanation: There's no free lunch. As explained earlier, at best, you can expect about 50% efficiency in converting electricity to motion (motor and controller losses of about 20%), then thru a drivetrain (5% loss) and then back to electricity via a generator (25% loss). Assuming you indeed deliver 100amps to your battery bank, this means that the battery is delivering 200amps of current to the controller just to drive the generator that delivers the 100amps. With only 200amps being drawn from the battery thru the controller total (your scenario), this leads ZERO AMPS for drive current. NET RESULT: ALL the Battery Power going is used to generate power, leaving nothing to drive the boat. Worse, the NET current from the battery is 100amps OUT…the battery bank will be out of power in 4hours or less and you haven't gone anywhere. -Myles Twete, Portland, Or. It takes a loud Lemming to stem the tendency of the other Lemmings to jump off the cliff. From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of GNHBus@aol.com
Sent: Thursday, February 10, 2011 9:29 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Cruising with EP How about a 420Ah Battery discharging at 200 amps/hr, with 100 amps being
returned by the high output alternator, will it extend the capacity of the
battery and range of the boat ?
In a message dated 2/10/2011 11:52:10 A.M. Eastern Standard Time,
matwete@comcast.net writes:
GNH offered: "You're last question about recharging the battery is the
best one."
And then also: "_http://www.pkys.com/alternator_installation.htm_
(http://www.pkys.com/alternator_installation.htm) Contact Peter Kennedy, he'll be
able to explain the In's & Outs."
I don't think these comments help.
Let's look back at what Mr. Garrison asked: "Will I be able to produce
enough DC from the alternator to charge the bank?"
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