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Solar Or Wind To Charge Field Box Battery?

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Old 03-11-2006, 11:10 AM
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Rcpilot
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Default Solar Or Wind To Charge Field Box Battery?

Anybody out there using a solar or wind generator to charge your 12V field battery?

I have a 285ah lawn & garden tractor battery in the back of my truck. I use it to power my field chargers. I thought it would be kinda neat to charge it with solar cells or a wind generator. Solar cells are looking pretty expensive. Wind generators can be home-made if you have the parts and the knowledge.

Anybody have any knowledge in these two areas?

Thanks
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Old 03-11-2006, 11:19 AM
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britbrat
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Default RE: Solar Or Wind To Charge Field Box Battery?

Anything can be done, but is it practical? Solar-electric @ ~ $10/watt capital cost, is wildly expensive unless you only want a smidgen of power. That's why you don't see any solar-electric generating stations. Wind is much cheaper, it can be as little as ~ $1.50/watt (about the same as nuclear generation) & even cheaper with junk-yard bits & pieces, but are you gonna lug that mess around with you?
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Old 03-11-2006, 12:26 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?

I don't want to get into a discussion of WHY I'm trying to do this. I have my reasons. Unless you really want to know about my personal problems and physical limitations, I'll just leave it at that.

Trust me, for my condition, it's practical to have a built in charging system on the truck. Be it a solar panel, or a small wind generator that can easily be removed from a base plate and tossed in the back of the truck when I'm driving.

I've checked into a solar panel, but most of them are simply a battery maintainer. They will keep a stored battery topped off and ready for use--but they won't charge a low battery in the amount of time I want. I'd like to be able to charge this battery overnight--or maybe in an afternoon.

There is lots of info about wind generators, but it's all large scale. Used for powering homes and farms in rural areas or off-grid locations.

Kinda looking for something that would use a 30" +/- propeller and a small DC generator for the wind generator. Or a solar panel that will put out 50-100 watts and have a reasonable cost. The only solar panels that I can find are up in the $700-$1000 range for this amount of power output.

My ideal charging system would deliver about 100W of power.

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Old 03-11-2006, 03:21 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?

RCPilet,
You could easily use wind to charge the battery while driving down the road.
But you could also use the truck charger to do the same thing.

That said, any DC motor connected to the prop will charge the battery.
The problems you must deal with are regulating the speed of the prop so as to not destroy the motor.
Then you have to regulate the voltage so you don't burn up the battery.
The electronics to regulate the voltage would be a minor problem.
Regulating the speed a whole different world for my puny brain (I used to be an electronics technician).
You need to talk to a mechanical engineer or technician for that.

Is the battery really 285 ampere hours? That sounds really big.

Good Luck,
KW_Counter
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Old 03-11-2006, 04:11 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?

How about a small gas genset mounted in the bed of your truck ?? ENJOY !!! RED
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Old 03-11-2006, 07:44 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?


ORIGINAL: KW_Counter

RCPilet,
You could easily use wind to charge the battery while driving down the road.
But you could also use the truck charger to do the same thing.

That said, any DC motor connected to the prop will charge the battery.
The problems you must deal with are regulating the speed of the prop so as to not destroy the motor.
Then you have to regulate the voltage so you don't burn up the battery.
The electronics to regulate the voltage would be a minor problem.
Regulating the speed a whole different world for my puny brain (I used to be an electronics technician).
You need to talk to a mechanical engineer or technician for that.

Is the battery really 285 ampere hours? That sounds really big.

Good Luck,
KW_Counter
It says 285 cold cranking amps on the sticker. Typical lawn and garden tractor battery. The battery in the truck is 875 cold cranking amps.

Can't use the truck to charge it unless I do some really fancy wiring and voltage regulating. The larger truck battery will cross charge into the smaller tractor battery all the time. It will boil the smaller battery to death in short order.

I have a 1/2HP DC motor in the shop, but it weighs a ton. If I'm gonna lug that thing around, might as well just take the tractor battery out of the truck and put it on a battery charger in the shop. Maybe could get away with a little bitty 1/4HP or 1/5HP DC motor.

I like the idea of the small gas generator. 2-stroke Tecumseh engine on a little package generator. I'm looking into that right now.
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Old 03-11-2006, 11:10 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?

Try this to eliminate some of the complexity of the situation. Use a voltage inverter to convert your truck DC into AC current, and then plug a standard battery quick charger in to charge the smaller 12v battery.

I run a setup like this all the time to charge all of my test equipment and gel cells in my work truck. It's next to impossible to take out my test equipment and charge in inside, so I just hook them to an inverter and charge them while I'm on the road.

Ken
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Old 03-13-2006, 12:57 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?

Well, all I know is, if I built a wind powered charger, it would tear a hole in the time-space continuim or something. Nature wouldn't be able to figure out how best to screw me, because if I didn't have the charger, the wind would blow like crazy. With the charger, it would be dead calm. I may have to build one just to seewhat happens!
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Old 03-13-2006, 02:20 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?

I’ve been thru almost this exact same decision. I have a deep cycle marine battery in my plane trailer I use to run lights, a stereo, power inverters for 120VAC, and of course 12VDC for my chargers. Wanted some way to keep the battery charged at the field. I looked at solar… Any solar panel that will deliver 100W at 12V will be very expensive. I only lightly considered wind. Like solar, a wind generator will work, but obtaining the 100W of power will not be easy, and you'll probably need extra stuff like DC/DC converters to adjust voltage for low/high wind situations.

What I finally decided to do is to charge the battery in the trailer from the truck. Unlike your situation, my batteries are basically the same size. I use a fused line, with a relay triggered from ignition. This way, the trailer and truck are isolated when the truck is off, idea being I can't discharge the truck battery at the field. I also have a solar panel on the trailer. I can't remember the exact size, but it will completely recharge the battery in the trailer in about 7 days, assuming good sun. I got wholesale pricing on the panel via an business account I have with Interstate Batteries, but it was still pricey. This setup seems to work. Been three years, no fried batteries in the truck or trailer, alternator is fine, trailer battery stays charged up, etc. Cheers.
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Old 03-14-2006, 08:46 AM
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Default RE: Solar Or Wind To Charge Field Box Battery?

Try this link as a start: http://www.otherpower.com/otherpower_wind.html

There is alot of info there and one particular link for the science fair wind generators leads to other interesting sites for small generators. Hope this helps.

Steve
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Old 03-14-2006, 02:31 PM
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Default RE: Solar Or Wind To Charge Field Box Battery?

Use a voltage inverter to convert your truck DC into AC current, and then plug a standard battery quick charger in to charge the smaller 12v battery.

Thats what I do too...
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