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Stage0 - a $20 wind turbine charging AA/AAA rechargeable batteries.

Discussion in 'Power Electronics' started by ChrisGreaves, Dec 30, 2020.

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  1. ChrisGreaves

    ChrisGreaves

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    Dec 29, 2020
    Thanks to Dave for pointing me here; if I have chosen the wrong forum I trust that a moderator will move the thread to where it should be.

    A introduction to me in the form of a fluid set of pages is at http://www.chrisgreaves.com/12vDC/

    My first of twenty-nine projects is to build a minimalist ("small cost") application of wind-power.

    (1) This Vertical Wind Turbine is available from Amazon. Rated Power: 0.55 W Output Voltage: 0.01V~5.5 V Output Current: 0.01mA~100mA. At under $20 the price is right; there are many different models. The voltage will not charge a 12vDC car battery – that comes later – but I thought that I could recharge some AA/AAA rechargeable cells. I have a dozen or so rechargeables tucked away somewhere.

    (2) A typical AA rechargeable cell is labeled 1400mAh, Nickel Hydride, 1.2v.

    (3) I have purchased an entry-level multi-meter from Canadian Tire

    (4) I have purchased a Reactor 28 + 4 LED Double Sided Work Light (model 3646-428). In theory at $4 I can cannibalize this for LED lights. (There are five more flashlights in stock just two hundred yards from my home!)

    At this point if I blow up everything except myself then my dollar losses can be borne! Air-borne even!

    I have not yet ordered the turbine but am ready to do so. The link above leads to several turbines under $20. I can/will buy the one best suited to my task.

    The product of this first application should be:-

    (1) A vertical-axis wind turbine mounted on the wooden rail of my porch.

    (2) Wire connecting the turbine to a hand-built recharger cradle.

    (3) The recharger cradle holds as many cells as I am allowed.

    (4) Wire leading from the rechargeable batteries to one or more LED bulbs.

    The effect of this application should be that people walking by 244/7 will exclaim "How brilliant is Chris!", and ask me about 12vDC power from wind power.

    Questions:-

    (1) Is this project doable once I work out voltages, amperages etc. Timing is not an issue. If I can recharge only one cell per day I can live with that. My aim is to have a little light burning 24/7 from the wind source. (Bonavista is Windy!)

    (2) Is this project doable with a vertical axis wind turbine under $20 – that is, the educational style of toy.

    (3) My vague understanding is that the voltage output by a wind turbine is a function of the wind speed. Is this so?

    (4) My understanding is that rechargeable batteries can be damaged by overcharging. I can cope with that by playing with my multi-meter on an hourly basis during the day.

    (5) 1,400mAh means in theory I can burn 1.4 amps current but only for an hour. It means too that in theory I can burn 100 milli-amps for fourteen hours – but there is probably a sine curve somewhere that tells me "after ten hours there will be too little light for your 74-year old eyes to detect"

    (6) If I have to separate charged batteries powering an LED light from batteries being recharged, I can live with that for now.

    This LED/1.2vDC project can be thought of as "Stage 0". My next step will be to move to a 12vDC car battery as a reservoir, a more powerful turbine, and a 12vDC light/lamp. Call that "Stage 1". I reasoned that I am better off burning up $20 while I grasp the concepts of voltage, amperage, wattage etc and play with my multi-meter on the toy turbine.

    Thank you in advance for just being here and, I hope, for a few pointers.

    Chris
     
  2. Audioguru

    Audioguru

    3,042
    678
    Sep 24, 2016
    The very cheap motors used as generators have simple brushes and simple bearings that will soon wear out.
    What circuit (a diode?) will you use to prevent the batteries from wastefully powering the motors and spinning the windmills when there is no wind? A simple electronic circuit like used in a cheap solar garden light can disconnect the LEDs when the battery is charging.

    I have seen many boats that use a high quality vertical windmill to charge their battery.

    The 1400mAh AA batteries are also probably cheap and half-full of rice and might leak soon. My Energizer AA Ni-MH batteries are 2300mAh and last for years.
     
  3. Bluejets

    Bluejets

    4,424
    938
    Oct 5, 2014
    Ditto Sanyo Eneloop
     
  4. Audioguru

    Audioguru

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    678
    Sep 24, 2016
    Panasonic now owns Sanyo and their Japanese Eneloop batteries have new chemistry that holds a charge for one year.
    Energizer Ni-MH batteries are also made in Japan with new chemistry that holds a charge for one year.
    Batteries from ebay leak and hold a charge for only a few minutes.
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
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    Jan 21, 2010
    *sigh*

    Your posts would hold more weight if you exaggerated less.
     
    Harald Kapp likes this.
  6. ChosunOne

    ChosunOne

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    102
    Jun 20, 2010
    What Steve said. Plus, you can buy Panasonic/Sanyo, Energizer, Duracell, and other reliable brand-name batteries off eBay. I've had good luck using eBay, but I generally know exactly what to look for there. I have learned to look for sellers that give specs, e.g., manufacture or expiration dates of the product. I've also learned never to buy cheap no-brand Chinese junk. If there were a way to filter my eBay search to eliminate "Made in China" products, I'd love to know it.
     
  7. Audioguru

    Audioguru

    3,042
    678
    Sep 24, 2016
    ebay and others sell "Super-Heavy-Duty" batteries cheaply that are old carbon-zinc garbage.

    Recently I bought Duracell Ni-MH batteries and a fast charger at a very low price at Costco.
    8 Batteries for the cost of 4 anywhere else plus a free charger. BUT the fine print says, "Made in China" and the batteries have half the capacity of older ones and the charger is fast only because it charges half the capacity of older batteries.
     
  8. Audioguru

    Audioguru

    3,042
    678
    Sep 24, 2016
    Here is one of many videos about ebay fake batteries:
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
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    Jan 21, 2010
    Dear Reader,

    @Audioguru has trouble distinguishing the concept of "x existing", and the concept of "nothing but x exists".

    His warnings are so shrill as to counter his message. If he were more measured in his delivery, concentrating on the risks of getting fake products rather than his apparent view of it as a certainty, the availability of genuine products would not be a trivial death knock to his argument.

    A more nuanced argument might focus on the elements that one should beware of in seeking to mitigate the risks, and possibly actions one could take in order to rectify the situation if one is taken in.

    But alas, even though we've tried, he's convinced that nothing good can come of eBay (and presumably China).
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
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    Jan 21, 2010
    Chris, you deserve a considered response to your post.

    I see nothing wrong with this for experimentation. However it's really more a toy than a useful product.

    For simple recharging, I would suggest you look at LIPO batteries. All they require is a current limited voltage source, and there are many very cheap modules that can be used to manage the charging.

    NiMH are not trivial to charge, less so if the source of incoming power is intermittent.

    That should be fine for what you're doing. If you've never used a multimeter before, be VERY careful with measuring current. It's a great way to destroy stuff if you don't do it the right way (and the apparently obvious way is the wrong way)

    Individual LEDs a re pretty cheap, but if you are able to cannibalize this, it should be fine. I wasn't able to see an image, so I'm assuming it isn't populated with surface mount LEDs.

    The "Starter Wind Turbine" would be a better option if you want to generate a useful amount of power, and be more suited to practical use. Although, because it's not a vertical turbine, you need to point it in the right direction.

    OK :)

    For a constant load, you need to be able to generate more power than is required for that load over a given period (determined by a number of issues including battery capacity and charge level).

    Maybe. In essence, it is perfectly doable as long as you are prepared to make your LED as dim as required to fit in with the constraints of available power.

    No, the power output is determined by the wind velocity. Power is Volts * amps. A load that increases the current (amps) will reduce the voltage output by the turbine.

    You might like to look up MPPT (Maximum Power Point Tracking). This is a technique used with solar panels and wind turbines (among other power sources) to extract the maximum amount of power. It's probably not necessary for the most basic of tests, but it would be for a practical design if it is to achieve useful efficiency.

    Measuring the voltage of NiMH cells won't tell you if they're overcharged :-( However this is exactly what you do for LIPO battteries. The modules I referred to earlier can be used to protect the cell against over charge, discharge, and charge current (and sometimes even discharge current)

    1400mAhr means that at some constant current load, the product of the load current in mA and the time in hours is equal to 1400. For some battery types this is often quoted for a 20 hour discharge -- but even this isn't constant! In almost all cases, a faster discharge (more amps) will result in a lower effective mAhr capacity, and a slower discharge in a greater mAhr capacity.

    Also, the capacity of a battery may decrease over time, AND some batteries are not designed to be discharged to zero (e.g. lead acid batteries)

    To make things even more complex, you need to put more energy into a battery to charge it than you got out of it while discharging. For NiMH, I think you need to put in about 40% more. While it varies for different battery chemistries, it's safe to assume something like this for most battery types.

    You shouldn't need to.

    That's probably a good approach.
     
  11. Audioguru

    Audioguru

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    Sep 24, 2016
    You said that your AA size Ni-MH batteries are only 1400mAh which is almost half as much as Energizer or other Name-Brand batteries. If you bought them from ebay then look online for battery tests that show some batteries from there are useless.

    Here is a You Tube test of some "crappy" Ni-MH batteries bought from ebay. Someone warned the guy that if they leak then don't worry, they leak sand.
     
  12. Harald Kapp

    Harald Kapp Moderator Moderator

    10,833
    2,442
    Nov 17, 2011
    Otoh this may be a honest rating, worth more than exaggerated 2000+ mAh of other no name batteries (I explicitly do not refer to the quality brand batteries you named).
     
  13. ChrisGreaves

    ChrisGreaves

    3
    0
    Dec 29, 2020
    Steve>> Chris, you deserve a considered response to your post.

    Steve, thank you for this response. You have provided the guidance that I need at this time. This is a short reply, but I will reply in depth once I have digested all your excellent remarks.

    Steve>> I see nothing wrong with this for experimentation. However it's really more a toy than a useful product.

    Quite so. A $10 turbine is a learning step for me AND an opportunity for anyone at my level to satisfy themselves that any one of the applications is doable. In the long term I need a reservoir, and 12vDC car batteries are available here in Bonavista.

    Steve>> For simple recharging, I would suggest you look at LIPO batteries. All they require is a current limited voltage source, and there are many very cheap modules that can be used to manage the charging.

    Following several references from www.electronicspoint.com I have begun attending Battery University, so I am sure that a five-year old NiMH battery is nit the best avenue for long-term use; it happened to be the first I grabbed at random from my box out in the shed. This "Stage0" step (AA battery and LED light) is supposed to be a proof-of-concept model to generate electricity by wind power, store it in a reservoir, and burn it in a visible light source. I am sure that if I collect car batteries from the three wrecking yards here in Bonavista and a source in St John's, that each 12vDC car battery will offer different capacities.

    Steve>> Individual LEDs are pretty cheap, but if you are able to cannibalize this, it should be fine. I wasn't able to see an image, so I'm assuming it isn't populated with surface mount LEDs.
    https://www.homehardware.ca/en/28-4...-hook/p/3646428?page=category page#ccode=8723
    upload_2021-1-4_6-40-39.jpeg
    [​IMG]
    A shoddy shot; 28 LEDs on the face and 4 LEDs (circled) as a flashlight on the end. I wanted to Get Started, and I figured that the multi-meter and a source of LED diodes(?) was a Start. At $cdn3.77+tax this was an affordable source, and was there to be taken home! (Delivery can be delayed out here on the tip of the peninsula)

    Steve>> The "Starter Wind Turbine" would be a better option if you want to generate a useful amount of power, and be more suited to practical use. Although, because it's not a vertical turbine, you need to point it in the right direction.

    I had dismissed the weather-vane-like propeller turbines as being unnecessarily complicated – more moving parts. The 15"-18" vertical axis types seemed better suited to being mounted on a shed/house ridge or in my case, mounted atop the two chimneys (no longer in use) with cables snaking down the chimneys Time will tell, and funds permitting I may buy and test several different types.

    Steve>> Questions:-

    And here we have my reason for time-to-digest! Many thanks for these observations.
    Cheers
    Chris
     
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