I have a trailer camper.  Everything in it will work off of 12v or propane except the air conditioner.  I can live without AC.

I am in the thinking about it stage, and need input.  I have access to an old fashioned windmill (think The Real McCoy’s) that is used to fill a stock tank.  I’m thinking of disconnecting it at the ground and running a shaft with 2 V-belt pullies driving 2 Ford alternators, connected to deep cycle batteries connected in parallel.  Those would be connected to my camper battery with jumper cables.

Does this sound feasible?

depends on how fast it will spin the alternator, they need  1800 at least to work best. Look for a 400 W marine plant, I have seen them for $400, use some steel tubing to get it high enough and you have one you can take with you

You only need to spin one alternator, and I would go with the smallest one you can source for free. It takes a fair amount of power to turn one, and the larger, the more it takes. You have to get fairly high to get into steady, strong breezes..

Do you have more wind then sun where you live?

$250 will get you a good 100watt solar setup. We have stayed off grid in our pod for 3 weeks straight. Dual Group 27 batteries. The solar panels we have are 100watts total, foldable, with the charge controller built in. We could have stayed longer we just ran out of her vacation time.

Check out this thread, there's a lot of data in it, and also in the link to Part 1 in the first post.


Charging with alternators

What do you need to power?  LED lights will run for weeks on a 12V marine battery.  That's what I use on my cabin.

The sun shines every day (even when obscured by clouds).

How often do you get wind strong enough to give a windmill a good workout?

Unless you happen to live in an exceptionally windy location, you're probably going to discover that your batteries are dead a lot of the time.

Aside from producing more predictable power, a solar system is also much easier to keep running - No belts, bearings, alternator brushes or other moving parts to fail.

Quieter, too.

1 horsepower = 745 watts

Just putting that out there for reference. As others have stated you need to be at least 1800rpm or better.

I think solar is a better option in most parts of the southeast US.

I thought that automotive alternators produced AC power where the OP said he was currently using 12 volt DA. He would need to "convert.' the current to store and use. Also why a Ford alternator. I thought that most projects using an automobile alternator tried to use GM alternators due to built in voltage regulators. Thoughts?

Thanks for all the comments.  The windmill has kept the stock tank full for 30-40 years, so the wind must be pretty strong.  I was just thinking I could take advantage of an existing windmill (on the cheap).

It if only blows once ever several weeks, you'll still need one hell of a large battery bank to tide you over.

That's one the nice things about solar systems - The sun shows up every 24 hours - and supplies steady power for 4-6 hours per day - so you don't need much battery capacity to supply power the rest of the time.

Mike, I was watching a modern windmill today, with lots of blades and turning relatively slowly. There wasn't much wind.

It was located at some large ponds and I couldn't tell what is was doing besides pumping water.

When you think about RV pumps and the relatively low current at 12 vdc and the impressive amount water they can transfer, with relatively low head, this suggests that the type of windmill we're talking about -low RPM, high torque, small horse power, would likely not be able to generate a lot of watts for battery charging.

There are specialty alternators, 3 phase usually like auto alternators, but using permanent magnets for the field, [see Google or ebay] that might make useful output if you can use a gear or belt transmission to step up your windmill's RPM to run them.


This is just a guess, I'd say the windmill I looked at today, good sized and nice condition, would have ~1/3 of a HP available [after losses] to drive a specialty PM alternator.


If you reviewed the link I posted above, you'd see I get about 100 amps at 14 vdc from a truck alternator driven with abt 3 HP.


If you look at the lift [feet] the water is raised, and the volume of water pumped, you can easily calculate the work being done by your windmill.


I think it is feasible to generate a SMALL amount of power with your windmill, and considering it doesn't cost anything to do it, and if the wind is reasonably constant, you will probably have a useful means for a small amt of juice.

The trick will be the gearing and using the correct permanent magnet alternator.

A windmill to pump water is different that one for Electricity. It is for torque. to lift the water. to run an alternator, you need RPMS. if you have to add too much in belts and pulleys or gears... you won't be able to spin the alternator fast enough with the torque it needs.  When you spin an altenator it is easy, butenergize the fields and it takes some torque. A car alternator could take  1 to 3 HP to reach full power with it. Get a 400 watt Marine wind plant or solar panels or both to do what you want.

Looking at the threads, I have no idea what most of what you posted but you must have miles of wire in your shop Looks neat to me and I wish I was technically proficient to do such a setup. Well done. I just hope it's all safe and works well.

Solar power is a viable option  across most of North America.

 

Thanks everyone.  I'll go with solar.

Cool

I want to do something similar using a RV and a steel building.

Paul, can you describe your battery bank setup and post pictures? How do you feed it into the house? EDIT: also what are some good batteries?