Please Help Design A 100W +/- Wind Generator

[ChrisPilot]

I am a model airplane enthusiast.  Radio Control airplanes.  They are glow fuel or gasoline powered, depending on the size and style of aircraft.

I am using a small 285ah lawn and garden tractor battery to charge my niCd and niMH batteries in the airplanes.  I am disabled, and would like to design a way to keep this lawn tractor battery charged all the time.  I don't want to have to lift the battery out of my truck bed and place it on an A/C battery charger.  I'm looking for a self contained system that can be used to charge this small 12V battery with minimal maintenance.  

The battery is in the back of my covered pick up truck bed.  I can't charge it froom the vehicle alternator, because it's not the same capacity as the vehicle battery.  It would continually boil over and cook the battery in short order.

I only need a 2amp (absolute max 4amp) charging system to maintain the battery after using it to charge my smaller 6V niCD and niMH batteries for a couple days.

Is it possible to build a very small wind generator that will produce this kind of power?

I can come up with a tape drive motor, or I have a small DC motor (1/2HP) in my garage if this can be converted to a generator.

I'd like to mount this wind generator on a small pole/bracket and slip the pole into a mount on my truck bumper or even mount a stand on top of the  camper shell.  Pull a pin and disconnect the wires for traveling purposes.  Toss it in the truck and drive away.

Thanks very much for any help or advise you can provide.

[Titantornado]

I'm definitely not the person to ask about motor conversions, but I'm sure they could be used.  Have you considered a small solar panel instead? Say 35 watts minimum, 50 watts better.

[Countryboy]

You may want to consider getting a second 6V battery.  Hook the 2 6V batteries in series, and let your truck alternator charge them.

Disconnect the 6V batteries when you need 6V, and use the batteries one at a time.

That may be your easiest solution.

[craig110]

One suggestion would be to wire a small car inverter into your truck's electrical system and just plug a small battery charger into it.  You can get small (<100 watt) car inverters for around $30.

[whatsnext]

This is far and away your easiest option.

[ghurd]

Maybe a box fan conversion?

Cheap to try and not a whole lot of work. Though 2 amps is kind of a stretch in most wind conditions.

G-

[pickerol]

I think anyone interested in aerodynamics should have a micro mill in their bag of tricks. i'm trying to develop a small system yhat can put out about the same as a 10 amp car bat charger. Environmental conditions dictate what air power can provide...panel combinations rock!

[dinges]

There are plenty of reasons for going for windpower. I've seen no good ones in your post.

The easiest (thus: best) solution would be to charge that 6V battery from your car battery. It's how we used to do things when I was still flying R/C planes. If you connect them directly however, you will destroy the 6V battery ('boil' it, if you prefer). The 2nd best solution would IMO be the PV panel, not the windgenny.

You should be looking for a good charge-regulator that works on 12V input and can charge a 6V battery. Even a series-resistor might do the trick, if you carefully monitor the setup and know what you are doing.

Not wanting to be blunt, but the way and how you ask the question to me indicates you don't really know what you are getting into; building a windgenerator is several orders of magnitude more difficult/bigger undertaking than building a simple batterycharger or even buying one. Then again, if you build model a/c, you probably have some valuable experience when it comes to building things.

All this may be a bit direct, so ignore me if I'm wrong.

Peter.

[johnlm]

I agree with the last reply.  I think I would try using an LM350K adjustable voltage regulator running off your vehicle battery system regulating down to charging voltage for your 6 V battery.  The LM 350 is good for 3Amps.  Add a couple of resistors to set the output voltage, mount it to a heatsink and you are ready to go for maybe $10.  Lots easier  faster and simpler than trying to build a bumper mounted windmill and then driving around to get wind if its not blowing.

Johnlm

[ChrisPilot]

I must not have been clear in my original post.

I have a 12V lawn and garden tractor battery in the back of the truck.  It's 285 cold cranking amps.  My charging equipment for the planes relies on 12V input and then steps it down to 6V for the airplane battery.

I cannot hook the truck charging system to the smaller tractor battery, because the battery is of such small capacity when compared to the main battery under the hood of the truck.  In that situation, cross-charging will occur and boil the smaller tractor battery in short order.

The idea of using the inverter won't work.  If I'm going to invert my 900 amp battery in the truck and run it into a standard AC battery charger to charge the tractor battery, might as well just run an extension cord outside and do it that way.

Solar was my first choice, but having trouble finding a 35-50W panel that doesn't cost $500.  I can find 5w up to 18w panels all day long, but those won't actually charge the battery.  They are designed to trickle and maintain a stored battery so that it's ready to go after a long period of inactivity.

For right now, I'm using a standard a/c charger to charge the tractor battery.  Have to run an extension cord out the garage every couple days and plug it in.  Pain in the butt.

I really have NO IDEA how to build a wind generator.  So the comments about me not knowing what I'm doing are right on target.  I admit my ignorance.  Was hoping some of you might be able to point me to a wind generator or even a solar panel that more resonably priced.  Solar would be my preference, but my searches aren't yielding economical panels for my purpose.  

Thanks for the help

[commanda]

The charger which charges your 6 volt batteries; is 12 volt input because you are connecting it to the 12 volt battery you carry around; yes?

Put a cigarette lighter plug on it & plug it into the dashboard of the truck. This assumes you can park the truck close enough to where you actually fly the planes to be useful. I don't think you specifically said that you carry the battery in the trunk to where you fly the planes.

Second alternative; fit a second alternator to the truck wired to the battery in the trunk.

Third alternative; I know I've seen "black boxes" specifically designed to charge a second battery carried in a vehicle, seperate to the main battery. 4wd enthusiasts use them, I believe. Sorry I can't offer more info on them, never had to use one.

Amanda

[coldspot]

" "black boxes" specifically designed to charge a second battery carried in a vehicle, seperate to the main battery"

Battery isolater

Any Marine (Boat) store would have them

Also other black box type things that would work

"low voltage disconect" ect,ect.

"Battery switch"

Lots of options

[ghurd]

I disassembled a cheap 'black box'. It was a diode and resistor.

G-

[Jerry]

Chris.

The garden tractor battery charges at the same voltage as the car battery 14.4 volts.

Since the cars alternater has a voltage regulater it will never exceed this charging voltage.

The small battery is a fluded lead acid battery just as the car battery is and 12 volt lead acid batteries charge at 2.4 volts per cell no matter what there phisical size or amp capacity. 2.4 volts times 6 cells 14.4 volts.

This is the voltage of all new cars and trucks that come through our shop no matter if its a Honda civic witch has a batter not much larger then a garden tractor battery to a big Ford power strock diesel with 2 big group 31 truck batteries under the hood (14.4 volts fluded lead acid all the same.

The only way the small battery can be harmed is if the voltage goes higher then 14.4v but the regulater won't allow that.

                              JK TAS Jerry

[elvin1949]

Get a battery isolator for your truck charging system.It will charge the tractor battery seperate

from the truck battery and will NOT overcharge it.

later

elvin