2.4 watt dynamo hub - can it power both front and rear lights?

[Dick Desmond]

I'm using a 2.4 watt dynamo hub (Shimano DH-2R35-E) with a Lumotec IQ
Cyo R. It works fine. I would like to know if I can add a dynamo
powered taillight.

I appreciate any info you can offer.

Thanks,
DD

[Terran]

The short answer is: No.

According to literature, the common rear bulbs use .6 watt bulbs.
Your front bulb is likely a 2.4w so you'll need a 3w generator.

http://www.myra-simon.com/bike/dynamos.html

http://www.candlepowerforums.com/vb/showthread.php?13177-bicycle-generator-light-sets

[Peter Jon White]

I assume it can't. But I'm only assuming. If you were using a halogen
headlight, you definitely couldn't. But LED headlights are different.
So it's possible that it might be OK. I can't try it since I have no
2.4 watt dynamos to test with.

PJW

On Oct 30, 11:59 pm, Terran <terra...@gmail.com> wrote:
> The short answer is: No.
>
> According to literature, the common rear bulbs use .6 watt bulbs.
> Your front bulb is likely a 2.4w so you'll need a 3w generator.
>
> http://www.myra-simon.com/bike/dynamos.html
>

> http://www.candlepowerforums.com/vb/showthread.php?13177-bicycle-gene...

[David Chase]

It also depends on how the lights are wired. For "bare" LEDs, the answer is certainly yes, though perhaps they will be dimmer than running alone on a 2.4W system, or on a 3W system.

LEDs generally get more efficient the lower the current you put through them, and the cooler you run them, unlike filament light bulbs, so you would almost certainly get some light. Power LEDs will glow visibly (though not enough to illuminate your way) with currents below a milliAmp. The two taillights on my bicycle split 350mA between them, and they are still plenty bright in their respective colors.

David

[Dick Desmond]

Thanks everybody. I'm using a B&M Lumotec (LED) in front. So I guess
I will experiment. May take a few days before I get to it, but I will
let you know how it works out.

DD

[Savvas]

Hi Dick,

I'm pretty sure that one of the Shimano dynos that I have in the shed
(on one of my bikes) is a 2.4W model I bought in error via mail order.
It seems to work OK running a home made single 3 watt XR-E front light
and a B&M Toplight at the rear. I think I have the 2 lights in
parallel - I presume the Toplight has some sort of resistive loading
because the front still works. I understand that these power leds
actually run more efficiently when underpowered. Try it out!

Sam P.

[Paul Pickup]

hi for anybody reading this conversation at a later date im using a shimano 2.4w deore front hub with a busch muller cyo 60 lux headlight plus a busch muller 2c taillight and at 3 to 4mph youve got a constant full light output front and rear.... at a slower speed e.g.when pushing your bike up a steep hill at 2mph it will flicker on both but it does that even without the taillight added.i would recommended not to earth the negative wires through the frame and back to the headlight to avoid circuit compromising from water ingress or grease at the headset bearings-use twin wires to the back light.hide the wires out of sight under the down tube and non-drive chainstay and feed through the tubular panniers to the back mount ,cable clips at strategic points and save yourself worrying about AAA batteries!!