Another use for Hall effect.... Brilliant!

D

Deleted member 4366

Guest
Unfortunately, you can't get something for nothing. It has no friction, but it still has drag.

It's the same as a hub-dynamo, where the magnets don't touch the coils, so there's no friction in them either, but the drag rises in proportion to the amount of power that you take from it, i.e. no drag when the lights are switched off, but something like 7w of drag when you switch 5w lights on.

It doesn't matter how you generate the electricity for the light, the bike has to provide the power from it's own kinetic energy, which means that it slows down. With a small light, that's not much compared with the bike's total kinetic energy, and it would make little difference whether you used a friction device, windmill or anything else to generate the electricity.

You'd be better off strapping one of these to each of your cranks to get free electricity:

https://www.ukprintwarehouse.com/shake-torch-1-led-white-?gclid=Cj0KEQjwp83KBRC2kev0tZzExLkBEiQAYxYXOrzyjc5_c0Q78C86H7afxKpiTB4uR0AQS5gVcw3KkWAaAioX8P8HAQ
 

ScottA

Finding my (electric) wheels
Jun 6, 2017
24
10
58
Essex
I know there's a "cost" but surely the drag would be barely detectable?

It's like a very small magnetic windmill - still think it's really smart :)

 

GLJoe

Esteemed Pedelecer
May 21, 2017
853
407
UK
I know there's a "cost" but surely the drag would be barely detectable?
The lower the drag, the lower the power it can produce.
There is no free lunch!
Did anyone notice how much power or light output they are claiming? maybe its enough. I'd like to see some figures though.
 
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D

Deleted member 4366

Guest
According to the video above, it just flashes as the magnet comes past, which is what you'd expect.
 

basicasic

Pedelecer
Apr 25, 2017
48
41
Amsterdam
There is no such thing as a free lunch for sure but I can't see the drag on a bike from one of these being detectable by anything other than lab equipment. A 5 watt rated LED bulb lights up my entire kitchen to a decent brightness so a couple of LEDs flashing every now and then isn't going to take much power at all. They are being marketed as safety DRLs so they don't have to produce large pools of light for showing the way at night and when you consider the thumping great output of the electric motors in our case it won't be noticeable at all.

Flashing lights on bikes are certainly far more noticeable by other road users than permanently lit ones in my experience.
 

GLJoe

Esteemed Pedelecer
May 21, 2017
853
407
UK
There is no such thing as a free lunch for sure but I can't see the drag on a bike from one of these being detectable by anything other than lab equipment. A 5 watt rated LED bulb lights up my entire kitchen to a decent brightness so a couple of LEDs flashing every now and then isn't going to take much power at all. They are being marketed as safety DRLs so they don't have to produce large pools of light for showing the way at night and when you consider the thumping great output of the electric motors in our case it won't be noticeable at all.
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Dunno. My wife has a modern hybrid commuter with a shimano hub dynamo. You can actually perceive the drag when you switch the light on.
Maybe a brief pulse every now and then from this new system would work, however I'm still a bit skeptical. I nearly always use flashing lights when commuting in the daytime, but I think the lights I like best are around 80 lumens - and this is only achievable in flash mode. Anything dimmer is heading towards unsatisfactory (for me anyway), and somehow, I just can't see something like this product being able to provide anywhere near enough power for 80 lumens or so. In fact, I'm wondering if it would even be an order of magnitude from it, maybe even two!

And as for using it on ebikes, well....even more of a case as to why all should have a power outlet for driving lights directly from the main battery!
Its almost as bad as the question always asked "does the battery charge when you peddle" :)
 

Swinman

Pedelecer
Jun 13, 2016
66
11
Leicester
There are some sad peps on here that have to find the bad in all things this is a great idea for all and I thank you for bringing it to mine and all other people's attention, if it helps save just one person then it's worth every penny, we all forget battery's on clip on bikes and in dark areas it will help be seen so thank you again
 
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