GM lights

[marad73]

I just got a set of GM LED lights for ebike.  The diagram shows the correct hookup for front light but no hookup for back light.  I tested both lites on a bench power supply and found that the back lite comes on with either polarity, but the front ONLY ONE way.  What is the proper way to hookup back light? Does polarity matter on back light?
Thanks for help
Ron

[Bikemad]

Ron,

The rear light wires simply connect in parallel with the front one, as shown in the modified diagram:





Normally the bulb centre contact would be positive and the threaded body would be negative, but from your description it would appear that the rear light/bulb has some form of built in rectifier (possibly for use with a hub dynamo).
The terminal which is grounded must connect to the Black (Negative) wire.

Alan
 
LED lighting diagram updated 14/11/09.

[marad73]

Thanks Alan!
Oddly enough, my rear lite didn't have wires connected to it or markings in the plastic.  Thats why I was puzzled.  I'll just hook it up the way it seems to work.
Ron

[Nightwind]

so what is the limit v to connect the light in parrallel like this. I want to add a more powerfull light to it. Can any bicycle lights work well using this wiring set-up?

[Bikemad]

This method of wiring the lights is only suitable for GM's own LED lights, as they are specially designed to run on the full battery voltage, but with a very low power consumption.

If you were to simply wire another type of bicycle light in the same way as shown in the diagram, it would probably destroy the electronics which power the light (LED type) or blow the bulb's filament (conventional incandescent bulb type) the moment the switch was pressed.

Andrew has recently wired his bike to run some MagicShine 7.4V super-bright LED lights which are powered indirectly from the main battery by using a DC-DC step down voltage converter in the circuit.
This little converter unit works on the same principal as most of the newer mains adapters used for charging mobile phones.
It simply converts the high battery voltage down to the much lower voltage that is required to safely run the LED lights, this should ensure that they do not get damaged by too many volts (assuming the converter's voltage output has been correctly adjusted before connecting the lights).

Alan
 

[User1]

This method of wiring the lights is only suitable for GM's own LED lights, as they are specially designed to run on the full battery voltage, but with a very low power consumption.

If you were to simply wire another type of bicycle light in the same way as shown in the diagram, it would probably destroy the electronics which power the light (LED type) or blow the bulb's filament (conventional incandescent bulb type) the moment the switch was pressed.

I wish I had known this before I burned my brand new dynamo LED lights
I'm sure that at least in Poland almost no one would come up with an idea that some special lights are needed, because you can't even buy any. And there wasn't even a word about it in the diagram which I received with my MPIII...

[e-lmer]

It would not be unreasonable to connect your lights to a
voltage regulator like http://www.linear.com/product/LTM8050.

This takes up to 58V and gives you 12V up to 2A with only 2 capacitors and 2 resistors.