Wind generator for 12v battery - no controller?

I am looking to power an arduino pro micro, a NRF24l01 transceiver module and a beam sensor for a driveway alert project. I am looking at this wind generator on ebay, its pretty cheap, but the shipping to my country is 5x the cost of the generator itself.

http://www.ebay.com/itm/Wind-Turbine-Generator-For-Clean-Energy-Production-by-Pacific-Sky-Power/131248561011?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20131003132420%26meid%3D8495052150999986688%26pid%3D100005%26prg%3D20131003132420%26rk%3D1%26rkt%3D6%26sd%3D141347277981&rt=nc

[u]It says that it doesn't need a charge controller[/u], that it can be connected to a 12v [u]deep cycle[/u] battery directly. I assume this is because the turbine cannot produce enough over voltage to fry the battery.

My question is does this sound plausible to use on say a PREDATOR 12V BATTERY 9.0AH lead-acid battery? Does the AH rating affect the charging of the battery?

Hi, that’s what they are saying, the output of the generator is not a lot, however, it does not have any weather proofing.
To me here in Australia they are quoting $35.00 for a $1 item, I’d forget it, its a ripoff.

It is only a DC motor with a propeller, if I was you I’d google for DIY or homebrew small wind generator, you would be better off in my opinion.

Tom… :slight_smile:
PS, in fact that supplier seems to have a very expensive post and pack department.

Just get a hobby motor or one out of a old disk drive, propeller and a blocking diode. Then make your own. These only work in strong wind for 12 Volts. Better for 3 to 6 volts. The blocking diode prevents the battery from driving the motor.

Watch the shipping on things like this. It's that way so if you return it, you only get the $1 back.

Thanks guys, Definitely glad that I didn't pay $40 for a $1 item. Now that I actually look at it, its just what you guys described a $1 motor and a prop.

I know battery charging can be complicated, with the different types of batteries and charging cycles etc. If anyone knows of any particularly informative websites please post them up. I'm interested in the research, but it seems too complicated for what I am trying to achieve.

If I can get away with just a 12v motor, a prop, and a diode and that will keep the battery charged enough to run my 3 relatively low powered devices then I'll take your word for it.

Have you measured the wind speed at the location where you want the power generated.
Small wind turbines or wind generators are usually almost useless for generating reliable power
as the wind speed never gets high enough to spin the generator fast enough.
You would be far better off with a small solar panel.

Well luckily I don't need a lot of power. And doesn't it depend on the motor rpm? For example I've heard car alternators don't work for wind generators because they require an RPM unachievable with wind speed. Isn't the size of the wind gens somewhat relative anyway?

Don't get much constant direct sunlight over here, wind and rain usually. I read that to trickle/float charge (which is what I need I think) you need somewhere around 14.7v. So I am guessing a 12v motor will not be enough and I'll have to go for 24v or something.

But now I have a question about charge controllers. I know they cut the power when the voltage exceeds the threshold voltage for the current charging cycle (14.7v?) and dump it into a dummy load. Does this mean when the speed is too high the battery is not charging at all? And so with trickle charge it will only work at a pretty specific wind speed? Or does it somehow limit the voltage to 14.7 when it is exceeded?

I just want to make a bloody driveway alarm :/

When a windmill is producing charge power its alternator/generator/etc. causes the windmill to slow down. If the attached batteries become full and the charge controller stops taking power from the windmill then that braking force will no longer be present and the windmill will spin much more quickly and potentially destroy itself. Thus a charge controller designed for windmills will employ a dummy load to keep that braking force present and prevent those overspeed conditions.

For the wind turbine you have linked (which I would not recommend) you would just need a diode to prevent the battery from discharging into the turbine. The windmill would spin freely below the battery + diode Vf and then slow down when it reaches the RPM that creates the voltage high enough to charge the battery.

The picture of the battery you have linked shows that its "standby" voltage is 13.5 to 13.8V. When trickle charging you would aim for 13.5V in hotter climates and 13.8V in colder climates.

You asked if the Ah rating of a battery affects how it should be charged -- yes it does. The general rule for all batteries is that, for the best lifetime, they should be charged at a 10 hour rate; e.g. a 10Ah battery would be charged at 1A for 10 hours.

Jose demonstrates a basic charge controller in the summary in this thread: http://forum.arduino.cc/index.php?topic=254591.0

Your best bet is going to be to use solar panels; windmills, at a small scale, are not practical. If you can provide more details on how much power your project is drawing then you'll get better answers as to what to do.

syphex: If anyone knows of any particularly informative websites please post them up. I'm interested in the research, but it seems too complicated for what I am trying to achieve.

If I can get away with just a 12v motor, a prop, and a diode and that will keep the battery charged enough to run my 3 relatively low powered devices then I'll take your word for it.

Airizona Wind and Sun has a forum here http://forum.solar-electric.com/forum.php that has good info. That forum, like many forums, has a few strong opinions (their way and the wrong way) but there is also good info there.

I built one of the generators in Hugh Piggott's book. Or one of H.Piggott's books. His site here: http://scoraigwind.com/. Good clear directions and also an open mind about the possibilities.

YOU HAVE TO GET THE GENERATOR UP HIGH IN CLEAN STRONG WIND. (Does it sound like my way or the wrong way? Sorry about that.) A rule of thumb that I have heard and believe is: if it's windy enough to be annoying then it's windy enough to generate electricity.

Even though I had modest expectations for my wind turbine, I was still underwhelmed. Solar is simpler, more reliable, and produces more energy for less cost almost everywhere. My latitude is high enough for short winter days, which is why I wanted to add wind. But the solar really works far better.

I never put a regulator or controller on my wind generator -- simply rectify and put into the batteries. (The generator is 3-phase AC.) H. Piggott's turbine designs all have "tilt-up" designs to swing the blades out of the wind to prevent over-reving the blades.

EDIT: Your pic looks like a sealed battery. Look at the mfr's spec sheet. Sealed batteries usually have less tolerance for high voltage -- i.e. at 14.4 volts the water electroloyses into hydrogen and oxygen. With my flooded batteries I simply replace with distilled water 4 times a year. A small, sealed battery will respond more quickly to high voltage and may not tolerate high voltage.

Also forgot OtherPower site and message board http://www.otherpower.com/. The site and forum has changed since I last looked.

The turbine can supply peaks higher than 14.5v but the current is lacking to do any real damage. Since the motors rated for lead acid it will produce aroind 14-18v with a light load, but the battery will suck up the current and not go over, unless it happens to produce stupid amounts for current/voltage…

People use 240vdc rectified and fed into 12v batteries to “regenerate” them… as long as it does not boil and run out of water/acid it’s practically happy

But sticking a 14.5v switching regulator on the output is the best way for a lead acid.

It is not actually a $1 item until the end of the auction.

mauried: Have you measured the wind speed at the location where you want the power generated. Small wind turbines or wind generators are usually almost useless for generating reliable power as the wind speed never gets high enough to spin the generator fast enough. You would be far better off with a small solar panel.

Could you use a Joule Thief boost converter to get it to charge during smaller wind times?

The smallest solar panel I can find has these characteristics:

Voltage (max): 18V- Current (max): Up to 70mA

1.26Watts

Panel Size: 159 x 175 x 17mm

Is this good enough or pushing it? The small size is attractive.

Here is some information on the equipment I will be powering:

NRF24L01 Basic characteristics:

  1. 2 Mbit / s rate of the peak current of 12.5mA received
  2. In the 2Mbit / s rate @ 0dBm output peak current of 11mA
  3. 400nA power down mode
  4. 32uA standby mode power consumption
    5.130us fast switching and wake-up time
  5. With on-chip voltage regulator oltage regulators
  6. In the 1.9 to 3.6V low voltage operation
  7. MultiCeiverMT hardware provides simultaneous six receiver functions, 2Mbit / s high-quality VOIP makes it possible to
  8. 130 us quickly switch and wake time
  9. Has the on-chip voltage regulator oltage regulators
  10. Can work at 1.9 to 3.6 V low voltage

PRO micro

Features:

ATMega 32U4 running at 5V/16MHz
Supported under ARDUINO IDE v1.0.1
On-Board micro-USB connector for programming
4 x 10-bit ADC pins
12 x Digital I/Os (5 are PWM capable)
Rx and Tx Hardware Serial Connections
Our Smallest Arduino-Compatible Board Yet!

IR BEAM SENSORS

Technology:Infrared
Receiver range : <20m,Maybe range can be reduced to 30% in bad weather conditions:fog,rain,dust,etc
Infra-red frequency:1.92KHZ
POWER SUPPLY:12V DC
Wavelength:940nm
Input:RX 15mA-TX 30mA
Operating temperature:-20-70 °C
Relay output:1A max 30V

So I guess thats about 50mA or 0.6 watts. 1.26 watts probably won’t be enough then considering theres no sun at night?? What happens if the battery voltage drops below the float charge?

syphex:
The smallest solar panel I can find has these characteristics:
Voltage (max): 18V- Current (max): Up to 70mA
1.26Watts
Panel Size: 159 x 175 x 17mm
Is this good enough or pushing it? The small size is attractive.

. . .

So I guess thats about 50mA or 0.6 watts. 1.26 watts probably won’t be enough then considering theres no sun at night?? What happens if the battery voltage drops below the float charge?

That’s too small unless you need this only during the day. But even on a cloudy day it may generate enough to work.

It may be helpful to think of your electronics being powered only by the battery and having PV there only to charge the battery. You can find maps online telling the average daily hours of sun. If you can find that figure for winter or your rainy season, use that. From there you can find out how many amps of PV you need to charge the battery.

Float charge is usually only a little higher than resting voltage. For a 12V battery, the resting voltage should be 12.6 or 12.7. Float charge is about 13.2. The higher voltages in your earlier post would be for “bulk” or “acceptance” charging.

You ask about “if the battery voltage drops below the float charge?”. In the evening the PV will put out less and less voltage and the battery will charge less. Eventually the PV will put out only a few volts and the electronics will run on battery power and the PV will just do nothing until morning. Most PV panels come with a blocking diode so the battery doesn’t send current through the PV cells. It is possible to find a panel without a diode if you try hard enough – you’d then have to add a diode.

While the PVs running my house are pretty big, I have a smaller panel running just the electric fence controller for some fruit trees. The panel on that is 30cm by 9cm – about the same area as the one you describe. Max voltage (open circuit) 16.x volts. Max amps about .1A or 100mA. I suspect you’ll need something a bit bigger than this – the fence is a very low amp draw although it provides bursts of 4,000V. This little panel, though, has rehabilitated the “dead” motorcycle battery that I use for the fence.

There is another one at 4.5w, here is the advertisement:

This is a great little unit for keeping your batttery topped up, when not in use. Charging rate is small enough not to REQUIRE a regulator.. Simply clip directly onto your battery terminal.

These solar panels are ideal for charging SEALED LEAD ACID BATTERIES. Supplied with mounting brackets, blocking diode, 2m output lead cable with alligator clips. Mounted in a plastic weatherproof case. They are ideal for marine use. They can be mounted on their brackets, and moved to follow the sun, or can be mounted flat on a surface. They are tough, and can be walked on if mounted flat (on a yacht or boat). Ideal for charging batteries: in cars used infrequently, for lighting etc, etc. 1 Year Warranty

VOLTAGE (max): 18V - Current (max): Up to 250mA - Panel Size: 187 x 255 x 17mm

It says doesn't require a regulator, but I still need a charge controller? 18V is higher than 13.8V. What does this mean?

Info about a charge controller:

Solar controller for use with SOLAR PANELS up to a maximum of 144W. Stops your battery from overcharging and helps maintain a floating charge to keep the battery in a fully charged state and ready for use. 12/24 volts 12A.

Do l need this to allow the board etc as a load on the battery aswell? Wont connecting to the same terminals exceed the 9-12v supply to the arduino board? Since 13.8 is also higher than 12v?

You dont need a charge controller with a tiny Solar panel, as the battery will simply clamp the Solar panels output to whatever the battery voltage is. If the Solar panel can only make 250 ma , then as long as the battery is at least 2.5 ah or more , it will never be overcharged. You only need charge controllers with large solar panels that can make 100s of watts, or if you have a tiny battery.

mauried is correct, but I'd like to expand a bit on his comment.

Photovoltaic panels will generate very high voltage when not connected (open circuit or OC). As soon as you connect it to any load, a lightbulb or a battery, the voltage drops by about 20%. Connect your panel that generates 18V to a battery and it will only be able to generate 14.5V. Even then, it will only be able to generate 14.5V when the battery is mostly charged; when the battery is discharged it will accept amps so fast that the solar panel voltage will drop even more.

An empty battery will accept a charge easily while a full battery will require higher and higher voltages to keep charging.

When a battery and panel are approximately balanced, there is no need for a controller. It's not like they need to be matched to a gnat's wisker -- your 9Ah battery is big enough to balance the larger panel you posted above.

EDIT: If the battery and the drain on the battery are far too large for the panel, the battery would never be charged and would eventually not take a charge by any means. Or if the panel is far too large for the battery and load then the battery can be damaged and fail. But there's a pretty large middle ground when using PV panels and lead-acid batteries.