# Dynamo lighting

R

#### RogerC

##### Guest
Father Xmas provided a Litespin dynamo and a couple of front lights.
I have absolutely no knowledge of how electricity works ( despite A level
Physics -- many years ago).
My query is if I am only going to run a front light off the Litespin -- can
I put both headlamps on the bike -- in series ??,
one say on the forks aimed fairly close to the front wheel and one off the
handle bar aimed further out.
Does this then reduce the light generated by each lamp -- so that the total
light generated remains constant i.e I can have one light at full output or
2 at 50% each.
Hope this question makes sense to those of you who understand this sort of
thing.
Rog

M

#### m-gineering

##### Guest
RogerC wrote:
>
> Father Xmas provided a Litespin dynamo and a couple of front lights.
> I have absolutely no knowledge of how electricity works ( despite A level
> Physics -- many years ago).
> My query is if I am only going to run a front light off the Litespin -- can
> I put both headlamps on the bike -- in series ??,
> one say on the forks aimed fairly close to the front wheel and one off the
> handle bar aimed further out.
> Does this then reduce the light generated by each lamp -- so that the total
> light generated remains constant i.e I can have one light at full output or
> 2 at 50% each.
> Hope this question makes sense to those of you who understand this sort of
> thing.
> Rog

Lightspin is an oddbal, as it will not put out more than 6.5v. Put the
lights in parallel, and the fitting of an on-off switch in the lead to
one of the lights is probably a good idea
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

G

#### GwG

##### Guest
"RogerC" <[email protected]> wrote in message
news:[email protected]
> Father Xmas provided a Litespin dynamo and a couple of front lights.
> I have absolutely no knowledge of how electricity works ( despite A level
> Physics -- many years ago).
> My query is if I am only going to run a front light off the Litespin --
> can I put both headlamps on the bike -- in series ??,
> one say on the forks aimed fairly close to the front wheel and one off the
> handle bar aimed further out.
> Does this then reduce the light generated by each lamp -- so that the
> total light generated remains constant i.e I can have one light at full
> output or 2 at 50% each.
> Hope this question makes sense to those of you who understand this sort of
> thing.

Not sure about with the Litespin dynamo, but usually two lights connected in
series will only give half the power, providing the voltage remains
constant.
Watts = volts times amps, so by effectively doubling the watts, you would be
halving the available current when used with a fixed voltage.
Connecting the front lamps in parallel would solve the problem, providing
the output from the dynamo was sufficient to power both lamps, but this
would probably then not give enough power for a rear lamp.
Just had a look at the Litespin, and it seems these 'bottle' dynamos have
improved greatly over the years. The ones I remember did away with the need
for a rear brake.

A

#### Alan Braggins

##### Guest
In article <[email protected]>, RogerC wrote:
>Father Xmas provided a Litespin dynamo and a couple of front lights.
>I have absolutely no knowledge of how electricity works ( despite A level
>Physics -- many years ago).
>My query is if I am only going to run a front light off the Litespin -- can
>I put both headlamps on the bike -- in series ??,

Googling, the LightSpin requires secondary lights to be wired in parallel,
not in series, because its inbuilt regulation makes it behave more like a
constant voltage source than the approximately constant current source
of e.g. a SON or Nexus dynamo hub.

And, while it apparently will run two lights, there is an increased tendency
to slip, so you might not be able to reliably use both in the rain.
(Most bottle dynamos aren't as efficient as the LightSpin, so won't provide
6W without slipping, so most discussion of secondary lights refers to hub
dynamos.)

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