Classic & Vintage - Dyanmo Wiring Question
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09-01-11, 05:31 PM
I'm attempting to install a new bottle dynamo on an older front & taillight setup (French). There are single wires coming from the front and rear and I have no idea how to work these onto the new dynamo. Do I need to rewire everything? or can the older wire function with the new dynamo. I'm totally new to wiring anything so please use laymen's terms. Thanks.
09-01-11, 05:52 PM
You'll get the best performance by re-wiring everything. The old single wire setup used the metal of the case/fender/frame as a wire. You need a path (circuit = circus = circle) for the current to flow all the way from the dynamo to the light and back again. The frame by itself would be fine but the problem is all the connections between light and fender, fender and frame, etc can become loose or corroded over time and this will impede the flow of the current to your light. If you just add two wires all the way from the dynamo to the light you can insure you will always have a good current path and you'll get better light output.
Now that I think about it a bit, you also need to consider how to dis-connect the case from the second wire if you go with a two wire setup. You could either open the light case and try to isolate both sides of the bulb from the case (one side will already be connected to the single wire) or you could just connect the wire to the case. It would probably be easier to just crimp some sort of ring terminal onto the second wire and then connect that to a bolt that holds the light. Do try to get a good connection here and you might even want to seal it up with some type of liquid electrical tape or similar to keep it clean.
If you connect the second wire to the case be sure to read the instructions of your dynamo to see if it tells you which terminal to use for this purpose. It will probably be the ground or - (minus) connector. It might also be marked with a ground symbol of some sort (3 horizontal bars, etc).
09-01-11, 07:20 PM
Some of that makes sense to me. Here is an additional image of the inside of the headlight terminal.
09-01-11, 07:36 PM
Guess I disagree with Iowegian based on my experience with bottle and bottom bracket dynamos. I've never had a problem with the ground connection that's made through the frame of the bike - any wiring issues have always been associated with the separate wire and I see no reason to add a second wire between each light and the dynamo. If the existing wires are in good shape then just hook them up to the terminal of the dynamo (some have only a single connection for both tail and head light but it looks like yours has separate connections for each. You also want to make sure the dynamo mechanical connection to the frame makes a good electrical contact - some use a small set screw that cuts through the paint to assure a good contact.
09-01-11, 07:42 PM
So, you're saying to plug the front into one of the terminals and the back into the other ... and that that mount can act as a ground if it touches metal ... does it matter that the terminals are labeled positive and negative?
This is the only instructions that came with it ...
09-01-11, 09:20 PM
I have a few older Soubitez bottle dynamos that work fine without a ground wire (in fact, they only have one terminal) and one modern Spanninga unit similar to yours that I ran a dual line for a ground wire. However, I think a ground wire is unnecessary on a steel frame. Try sticking both bare wires into the positive terminal. If both wires are too large, you may have to splice the wire before connecting to the dynamo (so that a single wire enters the push-in terminal). Good luck. That is a great looking fender mounted headlight. By the way, you can usually find chrome Soubitez dynamos to match your bike's chrome accents on ebay for a reasonable price.
09-01-11, 09:25 PM
Oh and leave the headlight wiring alone. It looks fine. If the original bulb proves to be too dim, I have successfully installed screw-base 1 watt LEDs in my Soubitez bottle dynamo set up. Like these: http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=%2Fflashlights.htm. You want the E10-WHP. It will also greatly improve your tailight brightness as well.
09-01-11, 11:02 PM
That was the trick. Both beaming, I think I'll try that LED bulb. Thanks guys. I learned a lot today.
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