1.5 watt dynohub - inferior lighting performance?

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brumster
Posts: 319
Joined: 8 Sep 2009, 7:50pm

1.5 watt dynohub - inferior lighting performance?

Postby brumster » 30 Dec 2020, 8:56pm

Anybody running 1.5 watt Shimano XT dyno hub or similar? Just wondering whether 1.5Watts = inferior lighting performance? I see B&M have a specific headlamp for 1.5W dynohubs, so would this mean other headlamps will provide less brightness - particularly at slower speeds ie, when climbing hills?

alexnharvey
Posts: 1432
Joined: 10 Jan 2014, 8:39am

Re: 1.5 watt dynohub - inferior lighting performance?

Postby alexnharvey » 30 Dec 2020, 9:48pm

I have one, it's on a 406 20 inch wheel tandem with a regular 3w light. We have no hills here so I can't comment on that aspect. It seems adequate to me. With a little effort I could compare light output with a 3w dynamo powering it but haven't yet.


brumster
Posts: 319
Joined: 8 Sep 2009, 7:50pm

Re: 1.5 watt dynohub - inferior lighting performance?

Postby brumster » 31 Dec 2020, 8:46pm


alexnharvey
Posts: 1432
Joined: 10 Jan 2014, 8:39am

Re: 1.5 watt dynohub - inferior lighting performance?

Postby alexnharvey » 9 Jan 2021, 2:30pm

I had a chance to compare the light output this week from the 1.5w xt hub in a 406mm rim wheel and a 3w Shimano hub in a 622mm rim wheel when I met my wife riding the tandem home. On the plus side it was a real on the road test, on the other hand, the lights on each bike are different and they are mounted at different heights.

The 1.5w hub drives a trelock ls906i light (3w rated) mounted at crown height (low because of small wheels) whilst the other light is a Hermann mr8 marked as 2.4w and mounted just beneath the handlebar.

The 1.5w hub system was generating a small, cool white but brighter patch of light while the 2.4/3w system produced a more diffuse, warmer and larger patch. I think the most important difference was the lamp height and it has motivated me to try to move the tandem light up to the bars, or at least closer to normal crown height.

An update will follow when I have found or bodged a handlebar mount.

Greystoke
Posts: 377
Joined: 8 May 2018, 7:41am
Location: Lincolnshire

Re: 1.5 watt dynohub - inferior lighting performance?

Postby Greystoke » 9 Jan 2021, 3:15pm

The modern led lights use (mostly) much less than their halogen equivalents hence why the 1.5w hub dynamos were made. I'd imagine they are more efficient....ie less pedal effort.
Led lights rarely give true electrical loads just saying 3w refers to it's ability to run on a standard dynamo.....they'll probably be ok on the 1.5w.
I'd be interested to know of any tests for actual load on modern lights.

pwa
Posts: 13624
Joined: 2 Oct 2011, 8:55pm

Re: 1.5 watt dynohub - inferior lighting performance?

Postby pwa » 9 Jan 2021, 5:17pm

I noticed that SP now sell a nominally 1.5w hub, which also has (to my way of thinking) flanges too close together. But it is very small and light.
https://spacycles.co.uk/m20b0s133p3777/SP-DYNAMO-SV-9
It looks to me as though it does give 3w when up to speed but drops below that at low speeds, so gets the lower rating.
I tried the PV8 and it does flicker with an 80 lux B&M lamp at slower climbing speeds, which isn't great, so maybe that too just struggles to push out enough juice at low speeds. It would be fine at a steady 10mph but I don't always do that climbing a 1 in 7 lane in the dark, and I dislike the flicker. I'd say getting a hub to match the lamp's demands is wise. Is there a hub that can run an 80lux lamp without flicker at 5mph?
Last edited by pwa on 9 Jan 2021, 5:31pm, edited 1 time in total.

Jdsk
Posts: 5144
Joined: 5 Mar 2019, 5:42pm

Re: 1.5 watt dynohub - inferior lighting performance?

Postby Jdsk » 9 Jan 2021, 5:28pm

Greystoke wrote:I'd be interested to know of any tests for actual load on modern lights.

https://www.cyclingabout.com/dynamo-hub-power-drag-testing-schmidt-son-shutter-precision-shimano/
discussed here:
https://forum.cyclinguk.org/viewtopic.php?f=5&t=143332

Jonathan

Brucey
Posts: 42102
Joined: 4 Jan 2012, 6:25pm

Re: 1.5 watt dynohub - inferior lighting performance?

Postby Brucey » 9 Jan 2021, 6:17pm

DH-1N70 reviewed here

https://fahrradzukunft.de/14/neue-nabendynamos-im-test/

but only driving 12ohm or 24ohm loads

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

SA_SA_SA
Posts: 1989
Joined: 31 Oct 2009, 1:46pm

Re: 1.5 watt dynohub - inferior lighting performance?

Postby SA_SA_SA » 11 Jan 2021, 11:59am

The SP seems to really be an almost 3w generator rather than an intentional 1.5w hub.
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