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Micro windmill charger
By Parameter, Section Controls Posted on Sun Feb 26, 2006 at 07:35:06 PM MST
Got the windmill, need basic charger diagram

Hi guys, I built a very small windmill doing more than 500mA at 12v using a small stepper motor and box fan blade. Works beautifully but will wander between 3v and 15v and then above 30 mph winds, it just put itself out off the wind.
I want to charge the equivalent of 4 AA, C or D Cells with it, which seems a fine fit for emergency led lighting for the shack and the handheld CB's we have.
Now, I think trying to charge 6v battery bank at 3v is wrong... So I guess a simple zenner there would work all right. But I was thinking more of a small charger using mosfet to switch charging ON or OFF designed around a small zenner diode (6v)activating the base of the mosfet when voltage goes above the diode threshold.
Also, when the battery voltage goes above another zenner (8v), it would activate a relay (standard 6v relay)to switch from charging to load. I don't mind a mechanical relay here as it will be easyer to find, cheaper and will act as a load itself (tough quite small) but mosfets would be fine too.
It all seems pretty simple to me, but I wonder if one of you has done the same or could direct me to a simple shematic?
Thanks a lot
Parameter

Micro windmill charger | 2 comments (2 topical)

Re: Micro windmill charger (3.00 / 0) (#1)
by asheets on Mon Feb 27, 2006 at 03:50:31 PM MST

I'm doing something a little like this now. Here's my approach:

from my generator, go to a rectifier or diode bank (to make good pulsating DC with as little negative inrush as possible). A series/parallel set of zener diodes does the job for me.
from there, go to a variable voltage regulator set at just over 6 volts under load. I like something like the LM317 9http://imagehost.vendio.com/bin/viewimage.x/00000000/vakits/LM317TApplicationTO220.JPG?allow_mailing

_list=1&owner_id=886054&allow_track_link=1&track=0232fe2e7a-d8526&sp=0) but with a TO-5 metal case.

3) I charge multiple groups of 4 AAs (6V packs) to spread out the amperage. In my setup, I use 5 packs of four batteries. My VOC is something like 7.5 V, my (each pack is seperated by more diodes) I try to keep VCC between 5.8 and 6.5V (adjusting R2 and having a digital VOM at the battery terminals), depending on the condition of the batteries, and the amperage from the gen just after the regulator is 300mA. I haven't blown anything up yet when I have all 5 packs in the circuit, though I occasionally burst an older cell if I just have 1 or 2 packs hooked up.
_____________________________

Alan Sheets

Re: Micro windmill charger (3.00 / 0) (#2)
by Vince on Mon Feb 27, 2006 at 08:42:32 PM MST

You should be able to utilize a solar battery charger. Check out some of these:

http://www.discovercircuits.com/B/batt-chrg.htm

Micro windmill charger | 2 comments (2 topical)

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