It's really really windy tonight!

Hi guys, its 25-35 mph winds here and here's my update... The multimeter at the end of my 100' "too skinny" cord is reading 13.4 volts with it being connected to the 2 deep cycle 12volt batteries connected together as a 12 volt system. The charge controller reading is at 12.52. This is under really strong winds tonight. The blades are a churnin' away. This seems to be about as fast as they will go while connected to my batteries.

My questions tonight are as follows: If the volts are around 13 going into the 12 volt batteries, are they indeed being charged? And will the volts on the charge controller rise as time goes on if the winds keep up for say the next 12- 20 hours? Aside from the cord being not thick enough, is the tiny a** diode an issue with my setup? The diode is small with a skinny solid wire on each end. One end is to the + of my too skinny cord and the other is to the + of one of the two batteries. Even if/when I go with a shorter and thicker cord, will this diode be an issue to the battery charging progress? I feel that something is wrong with my setup, as the wind is good and the multimeter is up in the 12- 13 volt range, but the batteries aren't going in to the 13 or 14 volt range. My charge controller has not once had to dump the load from the batteries getting too fully charged. I know my system is close to working 'properly' but I'm not sure it is working to it's potential, any ideas? suggestions? Always, THANKS!!! Terry

A battery holds a lot of wind power.
It takes a while.
Bigger batteries, and batteries that are low charged, take longer.

A tiny diode is not very descriptive.
Diodes are rated in amps, and you supplied no amp reading.
I like to use a bridge rectifier for a sizable wind system.

12.52V is not full voltage, so the dump load controller should not be dumping!

"This seems to be about as fast as they will go while connected to my batteries".
Do not make that assumption.
Cube square law.
Not a lot more wind will make them go a LOT faster.
Things can go from boring to frightening in a couple MPH difference.
G-

Thanks Ghurd- I remember the cube square wind stuff from initial research... And it was even windier yesterday than the day before! My multimeter got up into the 14's and glad to report my setup seems quite secure in respect to safety with tower/height.. I have also noticed the windmill makes a noise as it turns, a 'tick' noise with each revolution. So in these past windy days, it 'ticks' as fast as I can verbally say ticktickticktickticktickticktick, maybe even faster.
An unscientific calculation equates to 5 ticks per second, x60 seconds =300 rpm's... interesting... Looks like it's going much faster than that... But I digress...

The small diode description is all I can offer as I don't know the rating of it. Nothing is labeled on it. I don't know what a bridge rectifier is or where to get one to use instead of a blocking diode...

I know the batteries are not fully charged at 12.5 volts. What I don't know is if for instance the windmill is sending around 13 volts consistantly for lets say 12 or more hours, won't this charge the batteries to full, even slowly? How long would it take to fully charge 2 deep cycle batteries from 12.5 volts to full with windmill sending 13 volts to batteries? Is there a mathematical formula to make decent estimations of time to fully charge batteries? P.S. My batteries say 125 amp hours on the labels... Does this mean anything to me? Terry

Lastly for this morning, I am using the wind produced power to my electric garage door opener. This current system seems only capable of occasional use, versus constant use as the batteries seem to draw down too fast for constant use, even at constant use of 75 watts. So this all seem to be a very expensive way to have infrequent use of wind power...although it is really really cool IMHO... Terry

Yes, 125Ah means something Far more than "tiny diode", "skinny wire" etc Assuming you want to prevent damage to your batteries, you should limit their draw-down to < 50% of their rating. Connected in parallel your maximum storage is 250Ah, and your nominal usable storage is .5 * 250 = 125Ah. @ 12V a 125Ah = a nominal 1.5kWh output. Suggesting that you could draw 75W for up to 20 hours. If you are running an inverter from your batteries and a device rated @ 75W from the inverter you could get from 40% to 75% of that run time, or 8 to 15 hours. (Assuming the batteries were at full capacity when you began.) In comparison, 1.5kWh from the grid should cost you between $0.10 and $0.30 depending on your local rates.

Power generation is an economy of scale phenomena. The larger the scale, the more economical. IMHO a sub 25kW wind turbine located in an area that has less than 8m/s sustained winds is a hobby oriented pursuit. As such it is not likely to ever recoup the money spent on it. I know there are tons of people who would argue with that statement, but it is based purely on the numbers. Even large-scale commercial wind turbines require careful consideration of location and government subsidies to make them economically viable. Having said that, I think wind turbines offer the most promise for viable RE. I also think small-scale wind mills (<25kW) help people realize exactly how much power they waste, and creative ways to reduce their consumption. Small-scale wind turbines also offer a viable power source for remote locations where the grid is not available.

It is very difficult to determine your charging rate from the figures you have given. What we would really need is the Volts and the Amps. Your Batteries are "clamping" the voltage, so you could be inputting as little as a few milliamps, or you could be inputting 20A, though I suspect the former is more likely. The power stored in your batteries is measured in Amp-Hours, there is a semi-linear relationship between the stored power and the number of amps in and out. The charging/discharging processes incur losses which means that 10A in does not give you 10A out; and in the real world the batteries charge best at some input curve that has nothing to do with available wind

Using your "skinny wire" as mentioned above severely restricts your Amps to the charging system. Power Lost = Amps ^2 * Resistance. The thinner the wire the higher the resistance, hence if your "skinny wire" has a resistance of 1 ohm (.00473 * 100 * 2 = 0.946ohms) you are loosing power as per the following table:

  Code:

                                                 Wire Loss
                                        Power to  to Used   Wire Loss
Resistance Current         Wire Loss   Batteries  Power     System
   Ohms      Amps   Voltage   Watts       Watts    Ratio    Percentage
     1        1       12.5       1         12.5    8.00%      7.41%
     1        2       12.5       4         25     16.00%     13.79%
     1        4       12.5      16         50     32.00%     24.24%
     1        8       12.5      64        100     64.00%     39.02%
     1       16       12.5     256        200    128.00%     56.14%
     1       32       12.5    1024        400    256.00%     71.91%

Where:
Wire Loss Power Ratio = Wire Loss/Power To Battery
Wire System Percentage = (Wire Loss) / ((Wire Loss + Power To Battery)


Of course, if your diode is only rated @ 1A or less (as it likely is) then increasing your wire size may well destroy your diode

Anyway, it sounds like you are having fun and learning. Those are the important things; you aren't likely to impact your power bill much with your hobby regardless of how efficient your system becomes So enjoy it and learn!

Fish

Hi guys. I followed advise and cut the 100' cord in half and doubled it up to the windmill and down to the batteries. I also put 1 red and 1 black wire loom over the orange cord wire down the tower. Looks cool! I also added white electrical tape around the tips and centers of each of the six blades so it looks awesome when spinning. And I can see it better at night. I have re-read my charge controller instructions and got it set up properly for my 12volt system. And for testing, I charged batteries with battery charger and it does indeed dump the load at my set dump load point. All good news!
So I had a great run of 3 days strong winds, but now on 3rd day of almost no winds.... My hopes of saving $$$ with wind power are gone... meter running backwards, etc. etc... but I do have the greatest sense of accomplishment with my semi-homemade windmill! Thanks to all who helped on this forum! My cam corder will be back from repair soon, and you tube video will be coming! P.S. Anyone new to this like myself, please use extreme caution with windmill and especially erecting the tower and unit! I nearly killed myself or at least caused great bodily harm twice so far....

Thanks for sharing. Looking forward to your video.