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steveb1475
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Joined: 11/08/2015
Location: United States
Posts: 1

Posted: 02:14pm 11 Aug 2015

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Hi all,

This forum seems to be a great source of information! I'm totally new to wind turbines but I am quite fascinated and have been looking for an excuse to build one.

I would like to build a portable turbine to charge the batteries (2 - 12v marine/rv) on my tent trailer when camping. I have a couple of servo motors that seem like they may be good as a turbine generator and was hoping to get some thoughts and suggestions from this community.

I've tested with a cordless drill but do not have a tachometer to be able to give good numbers. Using a three phase rectifier, I'm getting up to 120 vdc at the max speed of my drill (again, have no clue of the rpms's) and with a 2 ohm load resistor I get about 2 amps before the motor tries to twist its self out of my hand.

Here is video of testing, hopefully the link works and sorry for the crappy cell phone video...

Servo open voltage and 2 ohm load test

My initial thoughts were for a VAWT just because it seems easier to setup for a mobile application but I'm starting to lean towards horizontal the more I research.

Do you think that I can direct drive this motor with something small enough to be portable?

I was also thinking of trying these for blades on the VAWT:

They are just heavy plastic pipe insulation shells grommeted together that I will reinforce.

My thought was to mount a piece of aluminum flatbar across to the hub on the motor connected to a tube down the inside edge of the blades. If I go HAWT then I will most likely fab the blades from PVC pipe.

Electronics is one of my hobbies and I do a lot with Arduinos, Raspberry PI, etc. So for a charge controller I will most likely go with a variant of this:

Arduino charge controller

Looking forward to your feedback

Thanks,
Steve

Gizmo

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Joined: 05/06/2004
Location: Australia
Posts: 5078

Posted: 05:09pm 11 Aug 2015

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Hi Steve

Had a look at the video and the servo might be OK. It looks like it was making about 9VAC at about 60rpm, looking at the white mark on the drill chuck. So at a guess, you would have a cut in speed around 60 to 80 rpm to start charging 12v. Thats OK, maybe a bit low. Depending on how adventurous you want to get, if you were to pull the servo motor apart, you could reconfigure the windings as delta ( chances are its wired as star ), and that would increase the cut in speed and amps.

The blades should really have a near flat side, like a air craft wing, to give lift. You can buy blade extrusions, they cost money but have a proven record and save a lot of work. See http://www.thebackshed.com/windmill/Kits.asp

Yeah stick with HAWT if you can. VAWT's initially seam easier, but in the end we all turn to HAWT's.

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ

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