Does this seem to be the best answer,.....

Free Spirit Energy Windwalker wind generator systems and it is under $500.00

http://www.freespiritenergy.com/

article review:
http://www.truckcampermagazine...alker-wind-generator

I'd get a small solar controller to limit voltage to the batteries.

From the site:

Think of the Windwalker generator as a “trickle charger” for your battery or battery bank.
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That makes me think it is pretty low output.

I would suggest solar. It seems adequate sun is more likely than adequate wind. If one panel isn't enough to charge up after overnight usage, you can add another panel.

I guess it depends on where you go. I haven't seen the sun around here for a while. Meanwhile, WIND chill is -30...!

According to the site:

The windmill is rated 250 watts, 8.5 amps max, 30 volts (but at 12 volts, 250 watts/12 volts = ~20 amps... more like 12 volts x 8.5 amps = ~100 watts max) Max output would be at 30 mph wind.

It is rated from 8mph up to 30mph, I'd like to see the output at 8 mph where it will normally be running. (It does have the advantage at night, though)

For the solar gurus: How many watts of solar panels can we buy for $400?

I guess on calm days we could just drive around with it at 30 mph! Just watch out for those low overpasses. (Dang there goes another antenna and a generator too!)

I keep a small solar panel on the dash of my plow truck ahd the Barth then keep the battery up since the truck/ Barth are used only so often. -14 Mon -10 today (heat wave). About $10.00 from Harbor Freigth, still working after 10 years. All who wander are not lost.

quote:

For the solar gurus: How many watts of solar panels can we buy for $400?

90 W Harbor Freight

I have been watching the wind generators evolution for a long time. This unit is VERY small for the claimed output of 8 amps. Yes Steve I also would like to see the output curve vs. wind MPH. PVC propeller blades are nice, light but very fragile.

So far I have not found a suitable unit that would do more than a small trickle charge. By suitable I mean light, easy to assemble, mount, and store-able.

Lots of DIY sites for wind and solar that discuss various designs. There is no free lunch for power generation.

Physics says the energy of wind increases/decreases with the square of velocity...

At 15 mph (1/2 speed) the output (at 100% efficiency) would be about 1/4 of full speed,(~2 amps)

Drop it to 7.5 mph it would be 1/16 of full speed, maybe 1/2 amp or so.

So at normal wind speeds we're talking about 1/2 amp x 12 volts = 6 watts...

Like ED says, TANSTAAFL! (There Ain't No Such Thing As A Free Lunch!)

Solar cells are closer to linear with respect to intensity... 1/2 as bright ~ 1/2 output. (still no good at night, though!)

quote:

Originally posted by MWrench:
There is no free lunch for power generation.

Not free, but the cost of solar can be offset by the savings associated with solar. And, the price of the panels keeps dropping, pushed by the entry of Chinese panels. And, once you've bought the solar, you no longer consume fuel to charge batteries. And, there is a convenience and perhaps a saving of battery life with the automatic charging of solar. This is particularly useful if the RV is stored away from a charging source.

Smaller controllers can be bought used from folks who have added more panels and need a larger capacity controller. Sometimes 12V panels can be bought from a user who wants to upgrade to a set of matched panels for the advantages of MPPT, or wants a 24 volt system.