Problems wiring a two headlight SON dynamo system – HELP M

pmanley

I am fitting some dynamo lights to my winter training bike. It is my first experience with dynamo lights and I am having a few teething problems. The equipment I am using is as follows: SON Dynamo hub, all lights are by Busch & Muller and all have a standing light that will keep running for a couple of minutes when the bike stops. The primary light is a B&M Lumotec Oval senso plus 6V 2.4W; the rear light is a B&M Seculite plus LED; the secondary light is a B&M Lumotec LED Oval senso plus. The rear light is running off the primary light and works OK when the primary light works. I read on the internet that these lights tow headlight set-ups should be installed in series, so that is what I did. However, whichever way round I wire the series only one of the front lights works at any one time. If I wire in parallel both front lights work OK, but according to the experts this is not the way to do it. I have only tested these on the bike stand at about 16kmph or 10mph. Following my tests I have some questions hopefully there are some lighting experts out there who can assist me:

1. Why should the lights be in series and not parallel? I would have thought that parallel is preferable so that if one headlight fails the other will still run.

2. Why does only one of the two front lights come on when I wire them in series?

3. Does it matter which wire (black or black with white stripe) goes to which pole on the SON Dynamo hub? If not how do I know which light is acting as a primary?

4. Does it matter which way round the wires for the rear light are wired to the poles on the underside of the primary light.

Any suggestions or explanations would be gratefully appreciated.

pmanley

I managed to get both lights working by isolating one from the other. It looks to me like I have two options now:

1. Buy another R&M mounting bracket €11.00 for a single lamp to isolate and continue to use the lights I have already bought. I would also adapt the double bracket to fit one light only. This option means that both lights will be on or off, I have no single light option. Not a big problem but if one fails they both fail.

2. Buy a SON-E6-z headlight, with 3w bulb & bypass switch for use in dual (12v) installations for €75.00.

:?: Will this (option 2 above) work OK on the double R&M mounting or will I still have to isolate the lights from each other?

rdaviesb

Take a look at;

http://www.blayleys.com/articles/lights/page2.htm or http://www.peterwhitecycles.com/wiringinstructions.asp for instructions.

pmanley

I have decided to carry out three changes to fix my problem:

1. Mounting the two front lights on seperate brackets so that they are isolated from each other.
2. Buy an E6-Z as my secondary light.
3. Use the LED front light as my primary with the back light attached to this one.

Hope this work. I'll post here about how I get on with these changes.

T800

Just spotted the thread today. That setup should work fine, as it's what I have, except that the two front lights are not on separate brackets -- they work fine using the metal twin lamp fork crown bracket I bought from SJS five years ago. Have you had a look at the Peter White site? I found it very helpful.

Yesterday I fitted a Fly IQ Senso Plus as a new primary. It's a good deal brighter than the D'Lumotec Oval Senso Plus but, annoyingly, kills off my CatEye Cordless 7 computer when lit.

pmanley wrote:

I have decided to carry out three changes to fix my problem:

1. Mounting the two front lights on seperate brackets so that they are isolated from each other.
2. Buy an E6-Z as my secondary light.
3. Use the LED front light as my primary with the back light attached to this one.

Hope this work. I'll post here about how I get on with these changes.

pmanley

I have mounted the front lights on seperate plastic brackets. I am now using:
- primary light is the B&M Lumotec LED Oval senso plus
- secondary light is E6-Z
- rear light is a B&M Seculite plus LED
This system works great - no problems so far. The most dificulf thing was cutting away the plastic mounting brackets so that they would fit on my oversized handle bars. My advise to those who like me have no experience with lights is - buy a secondary light that is designed to be a secondary light - don't try to save money using a regular light (like I tried to do).

Note: after I had bought the E6-Z I was told told that they will be bringing out an LED version of the E6-Z secondary light soon.

Thanks to all for your help.