I have a fender-mounted taillight, a bottle generator (B+M) and an LED headlight (IQ fly). I'd like to add a second (rack-mounted) taillight.
Apparently, two headlights can be used with a hub generator, but would produce too much resistance (and thus slipping) with a bottle generator. I wouldn't think an extra .6 watt would be a problem, but am not sure how to go about it.
The generator should be a constant current device, according to this website:
http://www.m-gineering.nl/son12vg.htm. This means, as far as I understand it, that the voltage, and thus power, will increase, while the current will stay at .5 amp.
Since a typical 3 watt system has the headlight at 2.4 watts and the taillight at .6w, it seems that the resistance for the headlight should be 15ohm, and the taillight 60. I can't measure, since my multi-meter is broken.
In order to make everything work with two taillights, it seems that I would want a total resistance of 14.4ohms. Wiring everything in parallel would produce 10ohms of resistance, which wouldn't produce enough power. Wiring everything in parallel and adding resistors so that the headlight circuit would total 21.6ohms, and each of the taillights 86.4 ohms would seem to make everything work out on paper. Is this right? I found a website selling 6.6 ohm resistors, but can't find any at 26.4 ohms (not surprisingly). Is there any reason why 25 ohms wouldn't be close enough?
And does my plan to add the resistor in the middle of the wire using heat shrink tubing make sense?