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bigtk
Newbie

Joined: 28/04/2008
Location: Australia
Posts: 4

Posted: 10:24am 22 Sep 2008

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I have a 24 volt 100 watt 6 amp scooter motor. If I connect a 4.5 volt globe to it and spin the shaft by hand it lights the globe. If I attach a 12 volt festoon globe it just gets a glow in the filament. I then mounted it up geared it to around 4-1 and attached a 1.2 metre prop. The prop was spinning extremely fast and I connected a 12 volt globe to the motor and the prop almost stopped dead. I then tried a 3 blade prop with 500mm blades and the same thing happened. Any ideas as to how I can make this work. I have made wind/gens with printer motors and have attached 26 LED's (21 white and 5 flashing red) they work like a charm. I am a newbie so any help would be greatly appreciated.

Marcus20VT
Regular Member

Joined: 02/09/2008
Location: Wales
Posts: 49

Posted: 11:16am 22 Sep 2008

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Hi Bigtk - I have that same motor I think.
I attached my makita cordless and on full throttle, I recorded 7 volts DC. I'm guessing that that is at about 800-1000 RPM, so I'm guessing at 2000 RPM we should get enough to charge a 12 volt battery.
Didn't get a chance to measure current, but hoping for 3/4 amps?
Next puzzler is how to get the wind to turn it at 2000 RPM, or do you electronically double the voltage?

bigtk
Newbie

Joined: 28/04/2008
Location: Australia
Posts: 4

Posted: 01:17pm 22 Sep 2008

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Hi Marcus - Looking at your picture it is the same motor. The problem I am having is being able to get enough power from the wind to turn the shaft under load. I guess I will have to work out the correct gear ratio to do this, 4-1 ratio wasn't enough. I don't know much at all regarding the electronic side of it, if I can put a prop on it and it lights up a few lights I'm happy,lol.
The pic is of a couple of small gen I have made using printer motors which are 24 volt and put out around 5 volts.

absinthe
Newbie

Joined: 07/09/2008
Location:
Posts: 10

Posted: 11:07am 23 Sep 2008

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you might need to rewind the motor..

not to hard just time consuming and a lil annoying at times..

i just finished one :P

http://www.thebackshed.com/Windmill/FORUM1/forum_posts.asp?T ID=1317&PN=1&TPN=1

Marcus20VT
Regular Member

Joined: 02/09/2008
Location: Wales
Posts: 49

Posted: 09:13pm 23 Sep 2008

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Yeah - I might re-wind one of mine too.
Is there an idiot's guide anywhere?

bigtk
Newbie

Joined: 28/04/2008
Location: Australia
Posts: 4

Posted: 04:47am 24 Sep 2008

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Let me know if you find an Idiots Guide Marcus, I certainly need one, lol.

absinthe
Newbie

Joined: 07/09/2008
Location:
Posts: 10

Posted: 06:17am 24 Sep 2008

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it might just be that i have found one :P

http://visforvoltage.org/forum/motors-and-drives/1694

as for working out the number of windings.. if you spin it as is at the rpm you want it to "cut in" at and record the voltage (and the short circuit amps if you like)

then count the number of turns in the rotor before rewinding (probably 24) and then divide the voltage (probably about 5)by the number of turns.. then divide this answer buy your desired voltage= number of turns

5/24=0.2083

15/0.2083=72

so if i had 5 volt at 300 rpm with 24 turns i need 72 turns for 15 volt at 300 rpm

(at least i think this is right.. there will be changes from this because of resistance changes etc)

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