How I'm using my white wire.


Local time
10:40 PM
Jun 22, 2009
Los Osos, California
After about 300 miles of testing I'm now reporting on my lighting and charging system. First I should say that if you manage to run an acceptable lighting system directly off the white wire with no battery, then stick with that. My system required a battery since I planned on having turn signals, horn, brake light, tail light and head light.

I originally had 6v incandescent bulbs all around but have since switched to a good 6v LED 1154 tail/brake light bulb. The 20watt incandescent brake light bulb that I was using kept my battery from overcharging so I thought I might get away without the voltage regulator that I implemented. The last 200 miles have been during the day without using the headlight. That in conjunction with the lower current LED brake light has allowed the battery to reach 100% charge so I suspect that the voltage regulator is now keeping it from overcharging. So the regulator stays.

The charging setup that I use is a half wave rectifier that charges a 6v 1.3ah SLA battery. The positive half of the wave form works best on my motor though some people say theirs work best with the negative half (positive ground). Just hook the diode (Radio Shack part no. 276-1141) up to the white wire. Temporarily ground the other end of the diode to the running engine. If the engine dies, reverse the diode. That determines the correct polarity so as not to affect the spark.

The system that I use looks like this:

For negative ground:
----white wire----[diode I]----[+ battery -]-----ground

A positive ground charging system would look like this:
----white wire----[I diode]----[- battery +]-----ground

The voltage regulator is a 5w 6.8v zener diode and a 10ohm, 5watt resistor. You might get by with 2watt components. My larger 5watt components might be overkill. An even larger 10ohm, 10watt power resistor is also available at Radio Shack and it too will work. You will probably have to locate the zener diodes somewhere else.

The regulator circuit for a negative ground looks like:
ground ----/\/\/10ohm\/\/\/----[zener diode I]----[+ battery -]-----

The regulator circuit for a positive ground would look like:
ground ----/\/\/10ohm\/\/\/----[I zener diode]----[- battery +]-----

The charging circuit can keep the battery trickle charged but probably puts out significantly less than 1 amp. The 1.3ah battery lets me use my generator type headlight for about 30 minutes before the voltage starts to sag and it dims. To keep my battery topped up, I need to do 80-90% of my riding during the day. I may go to an LED headlight and try to make the system capable of 50% night-50% day riding. If you need to run your large headlight longer than 30 minutes at a time, use a larger battery.

Findings: Using the white wire, it is possible to implement a 6v battery and charging system that does not affect the engine performance. It is a pretty wimpy system but it works surprisingly well within its limitations.
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Do you have any pictures of this set up. I am thinking of using one of those clip on wheel generators to power a light but I also want a battery so it doesn't dim or go out while not pedaling.
I would have to disassemble everything to show much in a picture. I put the battery, rectifier, and regulator inside a 2.0"x2.5"x5.0" Radio Shack project box and mounted it between the seatpost and rear fender. White(power in), red(power out) and black(ground) wires run into the box.
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Here is my first upload of some pictures to this sight. The first one shows the battery box. The second one shows the wiring inside the box.

WHITE – white wire from motor
RED – to light, horn, switches, etc.
BLACK – black wire to motor or to ground
D1 – rectifier diode, I used Radio Shack 276-1141
Z1 – zener diode, 6.8v, 5w - 1N5342B
R1 – power resistor, 10ohm, 5watt, I used Radio Shack 271-132
F1 – fuse, I used a 5 amp fuse
B1 – 6v lead acid battery, I used a 1.3ah SLA
Battery box – 2.0x2.5x5.0 plastic Radio Shack project box
Mounting brackets – plastic conduit clamps from Home Depot


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Sorry to revive such an old thread but is it possible to use a dc to dc step up converter to have this white wire charge a 12v lipo battery?