Step-by-Step DIY Rectifier Instructions

[Pilotgeek]

Be careful with what battery TYPE you're using. Lead acids, NiMH and NiCD are pretty tolerant to just connecting to a power supply. Lithium Ion are not. 3.6v sounds like it may be a lithium ion battery, which have a tendency to start on fire without very special charging circuits to limit the way they charge. If it is Lithium Ion, it may have the circuits in the battery itself, or the wall charger. The 6.5v off the wall unit may get regulated down elsewhere. It also may just be a 3.6v NiCD pack, not sure.

Why not do some Google searches so you understand how battery charging works a little more? Wikipedia has some nice information.

 

[bigbutterbean]

I dont know what lithium batteries look like, but I think this is a 3 cell nicad. It was out of an older power tool and the cells are wrapped in brown paper or cardboard. when I removed the battery, I could see the cells uncovered. The tool itself was the only casing that the battery had. I was able to remove the charging indicator light, so I am going to take the battery and connect it to the engine and see if the charging indicator lights up.

 

[Pilotgeek]

The tool itself probably would've made a big deal about it on the package if it were Lithium Ion. It's one of those advertising points, and it's a relatively new thing. It's probably just 3 cell NiCD.

 

[bigbutterbean]

So it appears that my white wire is acting as some sort of ground. With the engine off, I connected one terminal of the battery to my headlight and the other terminal of the battery to the rectified white wire, and the light comes on. If I start the engine and connect the battery terminals as mentioned above, it kills the engine. I do not understand what is going on here.

 

[Pilotgeek]

Are you connecting the + part of the battery to the white wire? Charge with positive to positive.

 

[bigbutterbean]

what Im saying is, with the engine off, the white wire acts as a ground. I tried the battery both ways, and either way it kills the engine at idle.

 

[Pilotgeek]

Maybe it's a bad magneto?

 

[bigbutterbean]

I just installed it because my old one got wet.

 

[Pilotgeek]

Do you have a multimeter? Check the ohms reading between white wire and ground. I know the proper values are floating around this site somewhere.

 

[bigbutterbean]

I dont have a meter.

 

[Pilotgeek]

Get one. They're literally $5 and you could diagnose everything. When it's started, you could use it to see how much voltage the white wire is putting out, you could see how many ohms to ground it has, and once you have one, you'll surely find uses for it.

Harbor Freight - 7 Function Multimeter

 

[bigbutterbean]

my buddy seems to think that these magnetos are what he calls the open/shut door type, where as the door opens (rpms increase) more power gets through, and when the door begins to close (rpms decrease) that the accessories wire begins to act as a ground. I dont know if he is right or not, but it does make some sense. I have decided for now that I am going to use the 7.2v battery and charge it in my house and just use it when I want to run my lights. its not ideal, but its better than having no lights at all.

 

[movinfast]

since we only ride at night part time and ride more in the day why doesnt everyone focus on runing the lights of a smal lead acid battery and trickle charging during day time riding.

 

[Pilotgeek]

Simplicity is the reason I don't use a battery with mine. Plus, I like running lights all the time so people can see ME. I get done with work late often too, so a lot of my riding tends to be when it's darker out.

A battery opens up many more possibilities though if it works for you. You could trickle charge during day riding, and then hook up super-bright 55w bulbs for night time, which would give you much better lighting than white-wire only lighting could.

 

[Radfletcher]

hey this thing was not difficult to build, and it actually works. another thanks for the tutorial!

so when I was at the 'shack picking up the caps and the resistors, I got my LED there too. of the numerous color choices, the closest I could find to 4.5 v in WHITE was a 3.6 v. and when it's running, the thing actually looks more blue than white. I admit to not being really knowledgable when it comes to LED's... anyone know if that might be a sign that it's being overloaded? the color is steady throughout the rpm range, and when the engine stops, I almost think I notice a *little* of the classic white color before the diode goes all the way dim.

again, this thread has been an indispensable resource (even for the non-electrician)

 

[Pilotgeek]

I've seen that color change before in LEDs. It may be slightly overloaded. Overheating can change the color of the LED. I've had green LEDs turn dark orange before going out. You're probably at the threshold of the LED, where it's hard on it, but not enough to immediately fry it.

You could try adding another small value resistor before the LED. Search Google for "LED Resistor Calculator", there's tons of them out there that make selecting a resistor value very easy for any type of LED and power source.

At the worst, you blow up an LED. They're somewhat pricy from Radio Shack, but I've been able to get packs of $100 high-intensity LEDs from china for around $5-10 including shipping costs if you need more.

EDIT: Just found info confirming that LED shifting to blue may be overheating

"Different color LEDs are made from different materials with different structures. Different materials react differently to excess heating: typically yellow and red LEDs degrade more quickly than green or blue. So an overheated white LED created from individual red, green, and blue LEDs will put out less red light, making the white appear bluer. "

 

[Radfletcher]

well okay then. I'll consider this an open and shut case, am I right?

all I'm really on the hunt for at this point is a higher voltage white LED that still 'seats' into the same mounting hardware as the one that's there now. once I know there isn't one? resistor city, here I come.

or else, of course, A higher voltage LED in orange or yellow? IF it is an option, sure. I don't see why not.

 

[Pilotgeek]

If you put two 2.5v LEDs in series, they act like a single 5v LED. Really though, the answer is a regulator. The LED flashlight I used has one built in which solves that problem.

 

[GearNut]

I would love to build a regulator to be able to power the insanely bright bicycle lights I have and mount them onto a 12 volt system on a Suzuki scooter.
12 volts in, 4 volts out.

 

[bigbutterbean]

I'm going to buy a mini-gen from wonderful creations on ebay to run my headlight. Running it off the white wire is no longer working due to the light killing the engine at idle. The min-gen is $25 plus shipping and will complete my lighting system, problem free. All I have to do is disconnect the white wire from the mag and attach it to the output wire from the min-gen. The light has a built-in voltage regulator, so no worries about overloading it.