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Both on this site and "in real life", battery-powered lights appear to be at least as popular as generator-powered lights.

I have always been slightly confused by this. To me, a generator-powered light seems the better solution if you need light regularly, because there's no need to worry about charging, and because they can be permanently attached. Yet many people seem to not only prefer battery-powered lights, they appear to not even consider a generator.

Why is that so? What are the advantages to battery-powered lights?

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4 Answers 4

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The main advantage, in my view, is that you can more easily add/remove battery-powered lights.

Why this may be desirable:

  • Theft resilience. I take my lights off the bike and carry them with me if I'm parking my bike outdoors for longer than a few minutes. Caveats: This can be more of a downside than a benefit, depending on your situation. (I can't imagine a thief taking the time to steal a generator-powered light, but I'm sure it happens sometimes.)

  • Flexibility. I don't bother to take my lights with me unless I know I'm possibly going to need them. If I used a generator-powered light, I would be pretty much stuck with it all the time, even if I'm only going to ride during the day. Caveats: This is, however, not much of a positive thing, unless the lights you use are particularly heavy, or you happen to be a "weight weenie".

  • Interchangeability. I can swap my lights between my bikes very easily. Most decent battery-powered lights have an adjustable removable clamp that you can use to attach the light to any style of handlebar/seat post/other tube that you could possibly want. This means that I only need one set of lights that I can use between all of my bikes. Caveats: If you don't like to spend an extra 5 minutes swapping your lights every time you want to ride a different bike, this is not a plus.

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Actually, point one and two sound more like disadvantages to me :-). The interchangeability is a good one though; I didn't think of people with more than one bike. –  sleske Feb 16 '11 at 17:15
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@sleske Yeah, hence the Caveats :). It depends on how you want to use your bikes/lights. I can see why some people would prefer to have a permanent system that is always available. –  Jason Plank Feb 16 '11 at 17:33
    
Hmm...I thought that one and two are advantages. It's pretty common for components to get stripped off of parked bikes. For example, at one point I had a seat stolen, which convinced me to remove it when parking. And, for 2, modern battery powered lights are easy to remove and fit in my pocket or pack. –  user313 Feb 16 '11 at 17:45
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I actually have 2 sets of lights for 3 bikes - all the bikes have mounts for the lights installed, so depending on what I'm riding that day, I can just toss the lights on that bike. No need to readjust the mounts. –  zigdon Feb 16 '11 at 21:47

Tyre driven dynamos can slip in rain or sleet. Hub dynamos can't slip, but do have a tiny amount of drag even when turned off. For a commuting bike, it's not enough to worry about, but on a high performance bike that you hardly ever use in the dark, with battery lights you don't have any drag from something you aren't using (and can leave them at home if you know you wan't need them). And you can get battery powered lights that are much more powerful than dynamo lights. You can always buy a bigger battery, but there's a limit to how much power you can get from a dynamo. (On the other hand, no battery will last forever, and dynamo lights never need charging.) Modern LED dynamo lights are really very efficient, but for some off road use, many people want more (and dynamo hubs aren't really designed for that sort of use).

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Battery powered lights are popular because of up-front costs and convenience. Also, the battery powered lights go with me between bikes.

These days one can get a set of bright, long-lasting, front-and-back, multi-attachable, battery powered lights for less than $30 (roughly 22.2 euros). And, that suits the typical recreational rider and probably most commuters.

A dynamo, means installation...at the most difficult is re-building a wheel; but easier is mounting a frame mounted wheel powered dynamo correctly...not to mention effectively wiring the bike. Many bike riders just don't want to deal with it.

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The cost is I think the main one. It's why I have one dyno hub between five-ish bikes. Also, I haven't seen a superflash rear dyno light, so even on my dyno bike I still use a superflash light on my helmet. Battery life is also now so long as to be ridiculous. With low self discharge rechargeables it's "recharge when you get around to it" territory - 100 hours of use or more. –  Мסž Feb 16 '11 at 22:53
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I've not gotten a dynamo-hub-powered light for the simple reason that it's be awkward and expensive to fit it up to a helmet light, my preferred style of headlight since I have four bikes I switch between. Four dynamo hubs and I'd have to be wired to the bike? Nope, not for me. If I only had one bike and I had lights on the handlebar, then I'd only be concerned with the cost. –  Neil Fein Feb 22 '11 at 7:43

Cheaper, easy to fit, more widely available - and don't take any effort!

Probably most people's memory is of the side wheel dynamo systems when they were a kid that wore away tires, put out a feeble light and turned off when you stopped.

enter image description here

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I don't think they are cheaper, at least not the decent ones (though there may be more extremely cheap battery lights). "Easier to fit" is indeed true. –  sleske Feb 16 '11 at 17:20
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And congrats about the picture. It very effectively stirs up bad memories of creaky side wheel dynamo systems with me... (though, to be fair, there actually are decent side wheel dynamos now, which rarely slip). –  sleske Feb 16 '11 at 17:22
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A 4*AAA LED front light for $15 is tiny and pretty bright. Rear flashing red LEDs from a dollar store are good enough for most people. –  mgb Feb 16 '11 at 19:02
    
all that needs to be said about Tire driven dynamos: youtube.com/watch?v=i7kgzgcqe5s –  mcgyver5 Apr 27 '11 at 15:10

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