Running lights with a dynamo

astrocan

Über Member
Location
Abingdon, Oxon
My front hub was on its last legs (sic) and I found a half decent dynamo hub for what I think was a more than fair price.
Having built it into a wheel I now need some lights and my eye has fallen on the box of semi-redundant battery LED lights that are just waiting for a new lease of life.
Getting the polarity correct is about the limits of my electrical expertise so I wonder if anyone could give me some pointers on what I should be considering when choosing which light to attack with a soldering iron and connect to the dynamo. Dynamo output is 6v 2.4W.
If possible, it would be extra useful to add a capacitor(?) into the system so the lights stayed lit when stationary for a short while but that might be asking a bit much.
Thanks for illuminating my dimness.
 

MichaelW2

Veteran
Most German std lights since 1990s come with a built in capacitor or something to give 2 mins of " standlight". They also optimise the light pattern for cycling compared to the generic battery lamps used by MTBers. They throw a concentrated rectangle of photons ahead and a peripheral star pattern to the sides to be seen. Very little light leaks up. Terminal connectors are solder free.
Mounting is on fork leg, crown or front rack. Handlebar is rarely used.
 

Trickedem

Guru
Location
Kent
My front hub was on its last legs (sic) and I found a half decent dynamo hub for what I think was a more than fair price.
Having built it into a wheel I now need some lights and my eye has fallen on the box of semi-redundant battery LED lights that are just waiting for a new lease of life.
Getting the polarity correct is about the limits of my electrical expertise so I wonder if anyone could give me some pointers on what I should be considering when choosing which light to attack with a soldering iron and connect to the dynamo. Dynamo output is 6v 2.4W.
If possible, it would be extra useful to add a capacitor(?) into the system so the lights stayed lit when stationary for a short while but that might be asking a bit much.
Thanks for illuminating my dimness.
I think you will find that the output from the dynamo is AC and will not work properly with a DC battery powered light. This is quite useful
 

JhnBssll

Veteran
Location
Suffolk
As mentioned above, you'll need a converter and voltage stabiliser to get a DC current out of a dynamo hub. If it were me I'd be buying a dynamo specific front light as the beam patterns are excellent compared to most battery lights. You'll get more of the useful bits of road lit up with a higher LUX level even with a lower overall lumen count with a proper dynamo light, and with road legal beam cut-offs so you won't annoy drivers. I run a Busch & Muller IQ-X on my commuter and its little sibling an IQ-XS on my Brompton and can't see myself going back to commuting with battery lights.
 
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