Getting 12 volt

[Singlespeeder]

I'm new here I hope this post goes through.
I am building a dyno based 12 volt bicycle lighting power system. i am running a shimano 6 volt hub threw a rectifier then a item called a any volt 3 that steps up or step down the voltage to what I set it at, which is 12 volts.

I have a mr16 12volt led 8 w flood as my close light a and a hard wired cree task force as my spot. only one 12 mile test run on it now. with the voltage of the battery going from 12.64 to 12.50 after the ride.
I only charge with a small solar cell in 3 hours of just plug it and leave it the voltage went back to 12.63

thanks for reading
Marcus
:wave:

 

[BrianMc]

If you can, post pics of the system on bike and even more hoped for, beamshots. Best if you can use the beamshot camera settings, if not your spot light on alone can be a reference.

 

[Singlespeeder]

The most important thing for me is the ability to a have a 12 volt system that charges of my dynamo. Lights will come second seeing while this my first and second led bike light.
The block on the left is a radio shack rectifier the thing with the heat sink is the anyvolt 3. It is a step up step down adjustable dc voltage regulator

 

[BrianMc]

Picture not shown. Not sure why. :thinking:

The forum format is 640-280, so if yours is much larger supply the link to the picture on the host site, or host a lower resolution copy for posting.

 

[Steve K]

has anyone tried operating the anyvolt from a dynamo? There can be "issues" when operating some switching power supplies from a power source that has a high source impedance such as a dynamo.

Fer instance... If the battery is discharged, the anyvolt will try to draw a fair amount of power from the dynamo. If the dynamo is unable to provide that amount of power, the output voltage will drop. If the output voltage drops, the anyvolt will try to draw more current, which will make the dynamo output voltage drop even more. Eventually, it effectively ends up shorting out the dynamo, and getting nearly no power from it. Well, this is what happens with a conventional switching power supply, and I would expect the anyvolt to be similar.

There are issues at the other end of the scale too. If the battery is fully charged and the anyvolt isn't drawing any power, it's very easy for the unloaded dynamo to produce voltages in excess of 30v (30v is the max input voltage for the anyvolt). From personal experience, I know that a Schmidt hub dynamo can produce over 100v at high speeds.

How big is the 12v battery? What type is it (i.e. SLA, NiMH, etc.)? It might be a simple matter of just rectifying the dynamo output and feeding it into the battery. Or, a linear regulator might be needed, although this will result in a constant 6 watt load even when the battery is charged.

Charging a battery from a dynamo can be done, but there are complications. You need to understand the capabilities of the power source, and the needs of the battery during charge and discharge operation.

To be honest, you can put together a nice little headlight with a couple of 3W LEDs that is adequate for just about anything. Adding a battery to your lighting system may be a lot more trouble than it is worth.

good luck,
Steve K.