Kinda off topic. I want to add led headlights and a ccfl or two to my pocket bike. I was thinking of a way to charge the battery as these engines are too small for an alternator. I was thinking for someway to generate current. Eureka it hit me, computer fans when spun generate electricity. My idea progressed to having the fan sit where air will hit it (rather then mount it to my sprockets lol) and when it spins, it will generate electricity to charge a small 12v battery. The only problem is, if I just throw the fans leads onto the battery, the battery will spin the fan. How can I limit the current so that it will charge the battery? I hope theres a way, thanks
the idea is good, but there is no point. The drag increase will put the same load on the engine as an alternator (actually more). The engine should be able to run an alternator as long as it's small enough Get a bike dynamo or something. Or buy batteries..
i got a pocketbike motor that has a alternatr on it. you could just get a small dc motor and attach it to the motor and that would work.
Its a fan, its just spinning blades moving air, I doubt it will add any more drag than me having on say... gloves. The second problem I have with an alternator is I dont know if its just as easy as running a belt from the motor (where would the belt go?) and wiring it to the battery. Ive never installed an alternator before so i have no idea. Sorry to sound stupid but what would a dc motor do for me?
if you spin the shaft of a dc motor it works as a generator. this would also work http://www.thebackshed.com/Windmill/assemblyMini1.asp but requires some diodes
Smilodon is right - there's no point. You'll get better efficiency by having a small alternator connected to your motor. The load the alternator places on the motor will depend on the current being drawn by your load. The same is true for any load connected to a fan, and the energy has to come from somewhere - in this case, your motor anyway...
Are you trying to make a windpowered recharger? I'm confused because it sounds like your saying one thing and the replies are about something else. Do you want to have a fan that spins because of the air moving throuhg it (generated by your bike going forward) and that spinning motion in turn creating enough energy to charge a battery? Sounds kinda complicated...
Are you sure? A few fans I've taken to bits have a rectifier diode in series with the supply so accidentally connecting reversed voltage to them doesn't damage the electronics; that means any generated power can't get out PC fans have brushless electronic commutation; again that means any power generated by spinning the rotor can't go the wrong way through the switching transistors. YMMV.
Well I hooked up 3 different fans to a multimeter and they all generated voltage and current. And hooking up one fan to another makes it so i can make the other fan move. Edit: I just took apart one of those fans and there is no rectifier diode. Some reistors, some type of small small square transistor, and a fan driver. Yes. Where would one find a small alternator?
At a small car parts store And as far as LED headlights go, some batterys would work great, as they dont draw much, you could even take an LED flashlight and tape it to the handle bars... I dont know what you want the CCFLs for though... As for your inquiry about using a dc motor to the drive belt, a dc motor spins the fan, therefore ising a dc motor to the drive belt is more efficient than a dc motor to propeller, relying on the air. Also, assuming the motor runs continuously, then the motor on the drivebelt will charge constantly, whereas if you are in stop and go traffic, then there wont be much air moving to spin the fan.
Yeah, Im definitly going to be using a small 12v battery. I just will need to charge it. Which either means I connect a battery charger to it overnight every couple weeks or I create some ingenious design to charge it while I ride. The problem with using a dc motor is theres no belt to attach it to. These things are basically chainsaw engines on a small bike frame. I want to use CCFLS because they light well while only using 5ma. (and led draws 20mA.
A bike dynamo from a bike store, Just put a small sprocket on it and put it inline with your drive chain. My brothers friend, has a mini chopper with a small engine like yours with an alternator, Look on ebay.
ehm.. what? I havent checked, but I'm pretty sure it draws way more than that. (think of the heat generated by at CCFL contra a LED) I would guess it draws more like 500ma.
