Using dynamo LEDs with batteries?

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cycle tramp
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Using dynamo LEDs with batteries?

Post by cycle tramp »

Given that the first five months of this year have simply flown by.. ...I guess it's time to think about winter lighting. In the past couple of years I've collected some dynamo LEDs front lights...
..I've still got lots of filament bulbs too... and I got to wondering if I should refit the filament lights so I've got a very basic level of lighting through lit areas and then use my LED front lights powered by batteries for those areas which are unlit.
Has anyone done this and how successful was it?
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rjb
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Re: Using dynamo LEDs with batteries?

Post by rjb »

Are you using the filament bulbs with the dynamo? Ive been using leds, hacked 3watt gu10's meant for 240V domestic lighting with my SA dynohub, which is rated at 1.8 watts but capable of more into an led load. I opened the bulb up and removed the internal electronics which had failed and then wired a simple bridge rectifier built from 4 diodes to rectify the ac to dc. Of course you could use the 12v mr11 or 16's which have the electronics built in to run from an ac dynamo. :wink:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
Bmblbzzz
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Re: Using dynamo LEDs with batteries?

Post by Bmblbzzz »

If you also have the dynamo to power your dynamo LEDs, I'd just fit them and not bother with the filament bulbs. The LED lamps will give far more light than the filament bulbs and won't be prone to blowing from over voltage either. I'd say there's no point using battery lights in addition to LEDs unless you really, really, really prefer the tone of incandescents.

If on the other hand you have no dynamo and will be using only battery lights, then the same basically applies with the rather big proviso of "if it works". I'll wait for someone with greater electrical knowledge than me to tell you how it might or might not be done.
cycle tramp
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Re: Using dynamo LEDs with batteries?

Post by cycle tramp »

Bmblbzzz wrote: 25 May 2022, 9:03pm If you also have the dynamo to power your dynamo LEDs, I'd just fit them and not bother with the filament bulbs. The LED lamps will give far more light than the filament bulbs and won't be prone to blowing from over voltage either. I'd say there's no point using battery lights in addition to LEDs unless you really, really, really prefer the tone of incandescents.
Thanks for the input, it's appreciated - however last winter I used a 60 lux and a 70 lux led headlamps.. and I've still got mixed views about them.
I found that the light they produced is very sort of 'thin'.. like the B&M photographs its fine if there's no other light source but the light from the leds sort of disappears in competition with street lights and house security lights and the leds seem to remove the colour from the surroundings...
..secondly the leds ain't cheap. I leave my bike in a number of public places and if I hang a light worth more than 80 squids from the front light mount, I've doubled the value of my bike... I wouldn't mind that much but I don't cycle in the night all that much now, but equally I like the freedom from having to remember to pack batteries or not to be concerned if I stay too late at a friend or family members house and cycle home in the dark...
...thirdly, to me the whole point of the dynamo system was that it could be fixed easily, bar dynamo breakdowns or wire breakages - I kinda like the idea of being able to change a bulb if it's blown. I've no idea what happens if a sealed led headlamp stops working partway through a night ride... call the AA and act surprised when they point out I'm riding a bike and it doesn't have an engine?
..fourthly, I've not been impressed with the light throw of the led lights, I seem to get a very bright almost white patch in the road, which makes it hard to work out if there's any surface defects which fades around the patch..
..so this year I'm going back to filament headlamps fitted with led bulbs. I tried it a few years ago.. however this year I'll be using two headlamps each fitted with a led bulb, one will focus a spot of light a few feet close to the front wheel, the other will be focused beyond that. I'm still going to get a 'thin' sort of colourless light, but if a bulb fails I can simply replace it and the ability to focus two lights independently should mean that I've got the ability to focus the light pattern in the manner if my choosing.

..however that does leave me with a surplus of led headlamps, which I'm wondering could be employed as a secondary light source from a battery pack..
Last edited by cycle tramp on 25 May 2022, 10:36pm, edited 1 time in total.
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rjb
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Re: Using dynamo LEDs with batteries?

Post by rjb »

You could also make a simple bridge rectifier and charge 4 or 5 AA rechargeable's in series to give you a 6 volt power pack to run your leds. :wink: This would also serve as a standlight. Something to consider. :wink:
Would you have enough power from the dynamo to run your filament lamps and charge your battery pack? i dont know but if you are experimenting let us know. :wink:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
cycle tramp
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Re: Using dynamo LEDs with batteries?

Post by cycle tramp »

rjb wrote: 25 May 2022, 10:36pm You could also make a simple bridge rectifier and charge 4 or 5 AA rechargeable's in series to give you a 6 volt power pack to run your leds. :wink: This would also serve as a standlight. Something to consider. :wink:
I really like that idea - I am thinking of getting a dynohub, and this would be a great way to use the kinetic energy produced from freewheeling down a hill, as apposed to wasting it as heat energy through braking... a sort of electric drag brake, as it were, with a 'positive' out come.
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rogerzilla
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Re: Using dynamo LEDs with batteries?

Post by rogerzilla »

LEDs with lower colour temperature are what is really needed, but:

1. this means more phosphor and greater light loss. It's easier to make a very bright bluish LED.

2. we've been conditioned to want the hi-tech "xenon" look after years of HIDs on upmarket cars, although they're also all LEDs now.

I also find the bluish LED light is swallowed up by wet roads.
Carlton green
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Re: Using dynamo LEDs with batteries?

Post by Carlton green »

I’m finding that what the OP is trying to do is confusing me and it looks like he could spend quite a bit of money and then move backwards, sorry.

Hub dynamos can be pricey and so can fancy LED headlights. LED bulbs that drop into filament bulb housings: are a tenner each, are dependant upon the condition of the old reflector and lens; have a questionable focal point; have a light output (spectrum) that might not be any more useful than what the OP already uses. Battery packs for bikes aren’t particularly common and rechargeable battery packs delivering 3 watts for some hours won’t be cheap. It’s easy to spend money - sometimes lots of it - and still have nothing more useful than what you previously had.

Perhaps LED lights do unexpectedly fail, but I’ve never heard of one doing so and an emergency set of LED battery lights (bough to protect against the risks of dynamo and wiring failure) can be had for about a tenner - I also carry a cheap head torch in my saddlebag and indeed a good head torch might help the OP too. If filament bulbs work better for someone then they’re still available, aren’t that expensive, can be protected by a zener diode (if they’re dynamo powered and one isn’t built into the dynamo), and if they blow then they can be easily changed. When at a standstill (no dynamo power) then small and cheap LED lights can provide safety illumination.

Night vision is important. Some lights work better than others and some eyes work better than others too. It would required an informed and scientific search but it might be that there are no significantly better light sources for the OP, that’s sometimes how things are and we’re left with making the best of what we have.
Don’t fret, it’s OK to: ride a simple old bike; ride slowly, walk, rest and admire the view; ride off-road; ride in your raincoat; ride by yourself; ride in the dark; and ride one hundred yards or one hundred miles. Your bike and your choices to suit you.
Bmblbzzz
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Re: Using dynamo LEDs with batteries?

Post by Bmblbzzz »

cycle tramp wrote: 25 May 2022, 10:30pm
Bmblbzzz wrote: 25 May 2022, 9:03pm If you also have the dynamo to power your dynamo LEDs, I'd just fit them and not bother with the filament bulbs. The LED lamps will give far more light than the filament bulbs and won't be prone to blowing from over voltage either. I'd say there's no point using battery lights in addition to LEDs unless you really, really, really prefer the tone of incandescents.
Thanks for the input, it's appreciated - however last winter I used a 60 lux and a 70 lux led headlamps.. and I've still got mixed views about them.
I found that the light they produced is very sort of 'thin'.. like the B&M photographs its fine if there's no other light source but the light from the leds sort of disappears in competition with street lights and house security lights and the leds seem to remove the colour from the surroundings...
..secondly the leds ain't cheap. I leave my bike in a number of public places and if I hang a light worth more than 80 squids from the front light mount, I've doubled the value of my bike... I wouldn't mind that much but I don't cycle in the night all that much now, but equally I like the freedom from having to remember to pack batteries or not to be concerned if I stay too late at a friend or family members house and cycle home in the dark...
...thirdly, to me the whole point of the dynamo system was that it could be fixed easily, bar dynamo breakdowns or wire breakages - I kinda like the idea of being able to change a bulb if it's blown. I've no idea what happens if a sealed led headlamp stops working partway through a night ride... call the AA and act surprised when they point out I'm riding a bike and it doesn't have an engine?
..fourthly, I've not been impressed with the light throw of the led lights, I seem to get a very bright almost white patch in the road, which makes it hard to work out if there's any surface defects which fades around the patch..
..so this year I'm going back to filament headlamps fitted with led bulbs. I tried it a few years ago.. however this year I'll be using two headlamps each fitted with a led bulb, one will focus a spot of light a few feet close to the front wheel, the other will be focused beyond that. I'm still going to get a 'thin' sort of colourless light, but if a bulb fails I can simply replace it and the ability to focus two lights independently should mean that I've got the ability to focus the light pattern in the manner if my choosing.

..however that does leave me with a surplus of led headlamps, which I'm wondering could be employed as a secondary light source from a battery pack..
You prefer the light from filament bulbs, understandable and personal. But to your third point, IME wire breakages are by far the most common failure on dynamo systems, at least with LEDs. The diodes themselves basically don't break (they do slowly degrade but that's a process over many years). So you don't need to worry about that bit.

As to theft of dynamo lights, doubtless it happens but it's not something I'd worry about unless I was leaving the bike overnight, or more likely over several nights, in a dodgy place.
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simonineaston
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Re: Using dynamo LEDs with batteries?

Post by simonineaston »

I found that the light they produced is very sort of 'thin'
I love the idea that light can be thin. As if it's somehow not quite proper light. It seems unlikely, however I have a couple of B&M led front lamps and I do know what you mean! One runs off a dynamo and another, itself a lamp designed for power from a dynamo, is fed by a 36v battery, via a converter.
S
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mjr
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Re: Using dynamo LEDs with batteries?

Post by mjr »

simonineaston wrote: 26 May 2022, 11:19am
I found that the light they produced is very sort of 'thin'
I love the idea that light can be thin. As if it's somehow not quite proper light. [...]
Light is both a thin wave and a thick particle stream.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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simonineaston
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Re: Using dynamo LEDs with batteries?

Post by simonineaston »

Oooh - do I sense another controversy stemming from a manufacturer cooking the books? Can it be that B&M have somehow managed to measure their lumens so that they suggest better peformance than the real world experience? Perhaps B&M went down the road to chat to their neighbours at VW... :wink:
S
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SA_SA_SA
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Re: Using dynamo LEDs with batteries?

Post by SA_SA_SA »

Warm white leds vs cold ones incur a 10% drop in lumens, ie not much , but if you view excess blue light as a simply unwanted waste light then you could view warm leds as more efficient at producing the sort of light you want....
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2_i
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Re: Using dynamo LEDs with batteries?

Post by 2_i »

Majority of LED dynamo lights works fine when connected directly to a battery in 6-7.5V range. However, there are some, e.g., B&M Eyc, that refuse to light up. As to the LED replacement bulbs, they tend to be low power and work OK for the rear lights but are disappointing for front. Besides the low power the issue is that the LED source is spread out differently than the filament in an incandescent bulb and plays poorly with the mirrors designed for the incandescents.
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