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How should I wire this all together? Answered

Hey guys, me again bugging ya's. I took some pictures today of some stuff I've put together and I want to know how I should wire it together to do something useful with it. Take a look at the pictures below, my questions are mostly in the yellow notes. I have another question though, I have this here 6v sealed lead acid battery and was wondering if it's possible to charge it using a current less than 6v?



wind project - i make a similar project using a computer fan. i face similar problems (intermittent wind and low voltage). when my inst will be ready ill try to include every possible hack how to make it work better (the capacitors and leds may be usefull) the solar panels sometimes output less power when they are exposed to too much sun. see if you get more volts when you tilt them with angle to the sun one panel is usefull for something compact but its tricky to charge 2 nimh / nicd batteries with (you need some active electronics to help). wiring 2 - 3 panels in series gives higher voltages which are easier to use the white led and blue leds look like any leds. you can use them for everything most leds can work at up to 20 mA. but blue and sometimes white leds have a distinct max efficiency point at about few mA. when you connect the led and go up with current it will go up amazingly well up to some amount of light (at very low current) and above it itll go up slower in light output. the point untill which it is very thankfull is the max efficiency point. its the best point to use a led in if you want to get the maximum out of your solar or wind project (amount of light vs time it works on one charge) and allows very long life of the led the motor can be used to generate power too. it will output pulsed dc and not ac. you still need 1 diode to charge batteries with it there are electrical wire clamps that are made of copper pipe and screws that go into it from the side. a small one should be ok to connect stuff to the motor you can insert a piece of isolation of electrical wire on the motor shaft and a thin pipe over the isolation. if you match things well it can go very accurate in any of the setups i think its better when the motor faces the wind (with its back) before the turbine blades and not the standard way. if you do it like that the wind will help stabilize the bledes on the shaft and not push them to the sides (usefull if your connection to the shaft is not very stable) the capacitors can be usefull with the wind turbine if you manage to get enough voltage to let yourself spend some on a diode (capacitors need diode) without a diode you can simply connect leds and resistor to the motor. it will flicker but work on lower speeds (than with diode)

To charge a SLA (Sealed Lead Acid) battery you need to create enough current at the correct voltage. The voltage is determined by the "cell voltage" (usually around 2.4v per cell.) A 6v battery should be made of 3 cells, or actually 7.2V. Check your particular battery specs to be sure of this.

So, now you have the voltage. You also need to know the capacity rating of your battery to design the charger.

From your description, you want to 'top off" the battery. This means you want to provide a "float charge." You do this by setting your charging voltage at 2.25v per cell (so 6.75v) with a current of about 10% of the capacity of your battery (4Ah battery would need 400mA) As the battery reaches full charge, it will draw less current, which you can use to monitor its charge.

SLA batteries are the simplest in terms of charging, but still require some math. The things working against you are that your charging sources are unlikely to generate enough current to charge the battery and the temperature conditions that you plan to use this in. Generating a higher voltage than you started with is not so difficult (boost regulator) but it lowers your available current even more. The voltage isn't going to be your problem, current is.

Anyway, you are essentially creating a "Uninterruptable Power Supply" and you should be able to find several circuits online.

Check out the "Battery Handbook" for more information: http://www.buchmann.ca/

Thanks RP! using an estimate of 2.2-2.4v per cell I believe is pretty dead-on. I think 7.6v is do-able but I'll need to add more wind generators (I need to wait till I can get some model plane props). I didn't think lead acid batteries ever completely died because they're sealed and can't oxidize inside the cells? >The things working against you are that your charging sources are unlikely to generate enough current to charge the battery and the temperature conditions that you plan to use this in. . Well I've tested both mini-windmills in shorted out conditions. It's safe to say that they can both make about 100-200ma of current each, although I've been dissapointed as it's been calmer than a deadbeat for the past 2 days since I installed them, and hence, I haven't been able to test them (I don't think it's my propellers, just lack of wind). As long as theres a diode in the output of the windmill, the current will slowly trickle into the battery won't it? Also, What do you think of using a couple motors from those tiny rc cars you charge up for 20-30 seconds and then drive for a few minutes. I have a couple that I am either missing the remotes for or the capacitors went bad or something. But that small of a motor, surely it would be easy to make a propeller that made it spin even in the lightest of winds? I'm really looking for a design that will spin in low winds, but also be able to make high current at high wind speeds, as we also have days where it will blow all day like there's no sign of stopping. I know it doesn't seem like much, but I think combined, I could make a useable amount of power, and if it's just from random motors that I'll never use anyways, why not??? One more quick question retroplayer, how can I connect the outputs together? Say I mount 5 of these little windmills outside (I plan to have multiple ones, all pointing in diff directions so I can always have one or two spinning, without having to make a windmill that turns to face the wind, making it maintenance free?) How would I connect them together? solder a diode to all the positives of the windmills? and connect all the negatives together??? Sorry for the dumb questions, but I'm more-less getting back into the electronics thing.

Do you already have the SLA battery? If so, the amount of current you will need depends directly on what the Ah rating is. "Spinning faster" will generate more voltage, not more current. A smaller DC motor will probably be capable of less current as the current capacity has more to do with the gauge of wiring, and total mass, I believe (not 100% sure.) As far as connecting all the sources together, hmm. The problem (which you probably already realize) is that if one of the sources are more positive than the other, current will flow into the lower voltage. Steering diodes would probably do the trick, but remember that a diode has a pretty hefty voltage drop. You could use schottkey diodes, which has a lower foward voltage (as low as .2V) I'm not really an expert when it comes to this sort of thing. I mainly work with digital electronics and am out of practice a little when it comes to power electronics, motors, generators, etc... So, hopefully someone will pop in that has experimented with this. I just thought I could help you out with the charging concepts.

I need to get to a shop somewhere that sells diodes and stuff like that, as well have nothing of the sort here. I pretty much figured as much, You've been great help to me and given me a few ideas for sure. I realize I really need to get somewhere that sells strips of components.

. I'm not sure about all the other stuff, but on mounting a prop (or whatever) to your motor shaft: . There are at least three methods used: press fit, set screw, and threaded. . Unless the shaft already has threads on it (doesn't look like it in the pics), that option is out (unless you have access to a lathe or other thread maker). . Press fit is usually for fairly low torque applications. Your small generator is a low torque application. You should be able to find a prop that will fit snugly enough. . Set screw is probably the best all-around option. It allows for some slop where the hub and shaft meet and will not wear out from repeated un/installation. . Check R/C airplane and boat sites for more info and other possible options.

Yes thank you nacho! I plan to make it to the local hobby store this week, and I'll see about picking up a whole bunch of props.

Come on guys! I want to hear some ideas of your own! Anything. I keep coming up with all sorts of ideas. Right now it's looking like I want to find some way to use multiple mini-wind gernerators, and some solar panels to keep a 6v lead acid battery topped up all the time, perhaps two if I can make enough power. Then I could regulate it at 5v and use it to charge my cell, mp3 player, I even have a usb AA recharger, why not? What about just running it mainly by charging from these mini turbines up in trees where you can't even see them. I suppose I'll have to be the first to find out!