dynamo lights problem - double wire front single wire rear

[frambo]

Hi,

I have a B&M front and rear dynamo set running off a shimano dynamo front hub.
the front light is a two wire lumotec senso (it has three switch setting - on/off and automatic switch on via light/dark sensor). the rear is a considerably cheaper single wire mudguard mounting type.

I have an overvoltage protector between the two lights.
i run the live and earth from the front dynamo into the front light then run two wires from that front light towards the overvoltage protector near the back light. then i take a double wire from that overvoltage protector with one live going into the slot inside the rear light (as it only takes a single wire) and the earth wrapped around the bolt that comes from the rear light mounting it onto the mudguard (which is metal)

i managed to get the lights working this way however;
i cant seem to get the automatic light sensor or the off switch to work for the front light and recently the rear light came loose and cant seem to get that working again. has anyone had experience with this setup?

i'm considering getting a double wire rear light but it would be nice not to have to waste the light i bought. any suggestions on what i might be doing wrong.

thanks

[jags]

hi frambo tiss i from boards fsl,
stick around your problem will be sorted 
sorry i cant help but theres loads here that can.
chers
jags.

[Danneaux]

Hi Frambo,

If I understand your problem correctly, I think it would be worth trying a re-wire before replacing parts. There may be other problems in the mix as well, so this is what I would suggest, in order:

1) Most generator-lighting problems are related to wiring and poor grounds. Both can be solved most handily by using double-lead wires throughout. Using the bike as a ground-return doesn't always work very well because the ground can "float" and prove unreliable over time. For example, it is a long ways from the fork crown to the taillight, and with bike-earthing, connection is also made via the headset bearings, which can be really problematic in practice.

Because of this, I would suggest first running new double-leads from the Shimano dynohub to the headlight, and again from the headlight to the present taillight. If it is a single-wire taillight, then one lead will replace the present one, and the second lead will be grounded to the mounting bracket for the taillight, providing the shortest possible path for ground-return. Basically, electricity will go down one wire and back through the other, and the bike will be left out of the equation.

I presume your taillight gets its power from the headlight; is this correct? If the headlight provides the power and the unused headlight ground lead (normally intended to run to a two-taillight) accidentally grounds against something like a brake caliper, it can lead to some of the problems you describe. It would pay to check this.

2) I am not sure which headlight you are using, as there are several in the B&M line that are called "Lumotec Senso". From your description, I think you may have some version of the Lumotec Cyo (an LED headlight). If that is the case, you probably do not need the voltage limiter, as that task will be handled internally by the headlight.

If you have an incandescent headlight and taillight, then I would place the voltage limiter between the dynohub and the headlight, and not between the headlight and taillight. If the voltage limiter is not needed, then it should be removed.

3) If neither 1) or 2) above fails to get everything working, then there is something else going on. For example, the sensor circuit inside the headlight may have failed, or the switch on the headlight may be faulty. This is not uncommon with some earlier models of IQ Cyo Senso headlights. Unfortunately, they are not readily repairable but can be replaced.

4) If you need a taillight, then a very good one is the B&M Toplight Line Plus, which uses two LEDs and a prism to spread the light in a band across the entire taillight lens. It is bright and noticeable without being obnoxious or irritating, and the larger lit area helps closing drivers to better judge their distance to you.

I hope this helps, Frambo. This is how I would approach the problem, and the process nearly always brings success.

All the best,

Dan.

[Cambirder]

I have a similar set up on my 2 bikes one running of a Sonn hub the other off a Shimano hub. You definitely don't need the protector in there, but it does sound like the front light is faulty if you cant turn it off. What happens if you run the front light stand alone?

[frambo]

Hi Dan,

thanks for all the information. It'll prove a real help to solving this problem. I'll let you know how i get on
cheers

Hi Frambo,


2) I am not sure which headlight you are using, as there are several in the B&M line that are called "Lumotec Senso". From your description, I think you may have some version of the Lumotec Cyo (an LED headlight). If that is the case, you probably do not need the voltage limiter, as that task will be handled internally by the headlight.

- i'm using the Lumotec Lyt senseo plus. from its description its an LED light and both lights are less than a year old.


If you have an incandescent headlight and taillight, then I would place the voltage limiter between the dynohub and the headlight, and not between the headlight and taillight. If the voltage limiter is not needed, then it should be removed.

-i'll try running the connection without the voltage limiter and see how i get on.


I hope this helps, Frambo. This is how I would approach the problem, and the process nearly always brings success.

All the best,

Dan.

[frambo]

so the front light is working properly again now its been disconnected from the rear light and the overvoltage protector.
no joy from the rear light, but i may need a new bulb for it and do a bit more testing.

thanks again for help

[il padrone]

I would suggest getting that double-wire rear light to resolve your problem. The rear light is not working, so it's something in the rear light or wiring to it. That second wire connected to the tail-light's earth pole worries me - I see the potential for an earth short.

A proper dual-wire tail-light would be the answer.