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Re: [a-w-h] Automotive alternators-don't throw out the idea just yet

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  • Hugh Piggott
    ... YOu only needed the high gearing to get it to self excite. So it might have been better to use lower gearing and to use a warning light circuit, or even a
    Message 1 of 5 , Mar 29, 2005
      At 11:41 AM -0500 29/3/05, David Simms wrote:
      > I would estimate the step-up to be around 12 to 1 including a bit
      >of fudging for slippage.
      >
      >With the field connected directly to the alternator output the
      >alternator would self-excite but, when the magnetic flux reached
      >full strength, it would almost stall the bike rider.

      YOu only needed the high gearing to get it to self excite. So it
      might have been better to use lower gearing and to use a warning
      light circuit, or even a direct connection of battery to field so as
      to get your excitation. A current through the field via the warning
      light does help to bring down the self-excitation rpm quite a bit.
      --
      Hugh

      Scoraig Wind Electric
      http://www.scoraigwind.co.uk/
    • kckclass
      Ok, glad this topic is finally hanging in there. If answered, we have cheap wind with manny/mo/jack/junkyard parts AutoZone store recently wrote and are
      Message 2 of 5 , Mar 30, 2005
        Ok, glad this topic is finally hanging in there. If answered, we have
        cheap wind with 'manny/mo/jack/junkyard parts'

        AutoZone store recently wrote and are interested. They are going to
        figure out which alternator (they have hundreds) will start at the
        lowest RPM and require the lowest field current/loss. I think that
        helps. We don't need 200 amp alternators here to get started-a 40 amp
        alternator at 500 watts is plenty for small 4 ft. blades.

        A 746 watt 50 amp alternator at 1 hp would work well with 6 ft. blades
        (at least in winter here in S.F.)

        A 1.5 kw alternator would probably work well with a 7 ft. blade.

        If a blade starts up at 200-400 RPM and can quickly accelerate to 500
        (600 - 1000 in really good wind), and a if most alternators I have seen
        are putting out 40 - 60 amps at 2000 RPM, a 3 to 1 or 4 to 1 pulley
        system would work.

        And as Hugh said, at the low RPMs there would be very little left for
        charging after exciting that field. This is it's second big drawback.

        Buy Kiwi I know with a sailboat does get a few amps at 14 knots with
        his lil 4 ft. blade and a simple 2 to 1 pulley system. Not too bad.

        I think I would first try a 3 to 1 or 4 to 1 pulley to focus on the low
        RPM aspects of the blade and use a deep angle of attack etc. in
        anticipation of the torque required and the low end speed limits.

        The trick with the pulleys is to minimize friction losses. Besides the
        belt method, we are exploring those silly minibike gear/tranny
        connectors to see what sort of losses they have. We'll see.

        In the meantime, we also found that while the ametek's are now almost
        extinct (everyone shed a tear) and becoming rare on eBay, there are
        alternatives - we found a 3/4 HP PM DC 3 PHASE 220/440 motor with a fat
        7/8 shaft - great for a 6-8 foot blade. AND it has a totally
        weatherproof/made for outdoors case - wonderful stuff.

        Ameteks were good, but these are decidedly better and still pretty darn
        cheap in dollars per watt. - about the same as the old ameteks.


        So...we'll explore both routes and if anyone has any fancy
        pulley/gearmotor ideas they'd like to share, as soon as I get
        a reply from the autozone folks I'll be a-testing something
        soon.

        Thank you for the ideas.
      • Frank Leslie
        This is an exceptionally good idea. News today was of a group trying to make millions of low grade notebook computers at a $100 price. These would be sold to
        Message 3 of 5 , Apr 4, 2005
          This is an exceptionally good idea. News today was of a group trying to make
          millions of low grade notebook computers at a $100 price. These would be
          sold to governments for distribution to children in third-world countries.
          They've signed on some large companies and there is a high chance of
          success. Here's a hint, but not the $100 story, at
          http://www.post-gazette.com/pg/05094/480909.stm

          Imagine the same approach to small wind turbines.

          Frank Leslie
          -----Original Message-----
          From: kckclass [mailto:kckclass@...]
          Sent: Thursday, March 31, 2005 12:21 AM
          To: awea-wind-home@yahoogroups.com
          Subject: [a-w-h] Automotive alternators-don't throw out the idea just yet




          Ok, glad this topic is finally hanging in there. If answered, we have
          cheap wind with 'manny/mo/jack/junkyard parts'

          AutoZone store recently wrote and are interested. They are going to
          figure out which alternator (they have hundreds) will start at the
          lowest RPM and require the lowest field current/loss. I think that
          helps. We don't need 200 amp alternators here to get started-a 40 amp
          alternator at 500 watts is plenty for small 4 ft. blades.

          A 746 watt 50 amp alternator at 1 hp would work well with 6 ft. blades
          (at least in winter here in S.F.)

          A 1.5 kw alternator would probably work well with a 7 ft. blade.

          If a blade starts up at 200-400 RPM and can quickly accelerate to 500
          (600 - 1000 in really good wind), and a if most alternators I have seen
          are putting out 40 - 60 amps at 2000 RPM, a 3 to 1 or 4 to 1 pulley
          system would work.

          And as Hugh said, at the low RPMs there would be very little left for
          charging after exciting that field. This is it's second big drawback.

          Buy Kiwi I know with a sailboat does get a few amps at 14 knots with
          his lil 4 ft. blade and a simple 2 to 1 pulley system. Not too bad.

          I think I would first try a 3 to 1 or 4 to 1 pulley to focus on the low
          RPM aspects of the blade and use a deep angle of attack etc. in
          anticipation of the torque required and the low end speed limits.

          The trick with the pulleys is to minimize friction losses. Besides the
          belt method, we are exploring those silly minibike gear/tranny
          connectors to see what sort of losses they have. We'll see.

          In the meantime, we also found that while the ametek's are now almost
          extinct (everyone shed a tear) and becoming rare on eBay, there are
          alternatives - we found a 3/4 HP PM DC 3 PHASE 220/440 motor with a fat
          7/8 shaft - great for a 6-8 foot blade. AND it has a totally
          weatherproof/made for outdoors case - wonderful stuff.

          Ameteks were good, but these are decidedly better and still pretty darn
          cheap in dollars per watt. - about the same as the old ameteks.


          So...we'll explore both routes and if anyone has any fancy
          pulley/gearmotor ideas they'd like to share, as soon as I get
          a reply from the autozone folks I'll be a-testing something
          soon.

          Thank you for the ideas.








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