Repurpose LED panels from a crumbled Amazon light to make bike lights?

guerney

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Might be of interest to those looking for bright LED panels for bike use: I used to use huge spiral 6400K CFL light bulbs in my living room, which actually used 105W, but they don't make those anymore so I bought this November 2020:





Like the CFL, it was very bright (much brighter actually) and a great help finding tiny dropped items such as screws bolts etc. However, after almost three years it went pop and the plastic crumbled. The LEDs might last the advertised 50,000 hours but the rest of it evidently doesn't - I expect it's planned obsolescence, to sell these LED lights more often. I have an older 3 bladed lower power version which still works, with no sign of crumbling.


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The diffusers remain intact and the panels function fine - the 5 LED panels are all very bright at 36V DC, dim at low voltage, I assume they're designed for about 44V but I don't have a power supply to test this. I could weld the aluminium heatsink of a LED panel (those are bonded to the panel backs) to 2mm aluminium sheet cut to the same shape of a diffuser, add orange heat resistant acetate sheet to the diffusers, then weld another LED panel to the other side, and bond another diffuser to make a double sided indicator light. There are 4 panels I could use for this, and four diffusers, to make two dual sided indicators. As indicators, I believe they'd be bright enough to be visible in bright sunlight. There's also another bright 73mm X 73mm LED panel.

Or I could bond them with diffusers to the fronts of my Zefal end-bar mirrors. Or I could make waterproof housings to attach them elsewhere on my bike and/or bicycle trailer as running lights. I'd be reaching for a 3D printer if I had one, so it's a jolly good job I don't - I have quite enough lighting on my ebike already, and no remaining space on my handlebar for any more switches (a longer handlebar would prevent my folding bike folding, as would a waterproof switch panel with many switches). It's more likely I'll use them to light my offgrid garden shed, powered by my 36V ebike battery. Preferable to adding to mountains of ewaste.


"The WEEE says its research shows the "mountain" of electrical and electronic waste - from washing machines and toasters to tablet computers and global positioning system (GPS) devices - will grow to 74 million tonnes a year by 2030. "

 
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guerney

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Tried this flasher unit, which works at 36V with those awful 6V-80V Bafang lights, but sadly doesn't flash the LED panels above.



It makes an intensely irritating weedy sortof engine noise at lower voltage. Two of these flashers at low voltage would sound even more annoying to everyone on the road - I can't decide if they sound more annoyng than bagpipes.

(Sorry about the middle finger salute. Force of habit, and I suspect some of you are drivers. ;))

DO NOT WATCH THIS BORING VIDEO


 
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WheezyRider

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Looks like the electrolytic capacitor has blown in the power supply module. Surprising to still see that these days. Use epoxy to glue the LEDs to a heat sink. You do need a current control module though to ensure the LEDs run properly.
 
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Sturmey

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Last year I dismantled a faulty domestic 470 lumens 230v 5.5w light bulb. It consisted of a small full wave bridge rectifier feeding its dc output to 9 leds ( and a resistor) in series. (daisy chain). One of the leds had blown and disconnected the chain. I was able to repurpose it to work at 36v by using 4 of the working leds in a 2s2p type configuration with a resistor in series to stabilize the current . I think the leds should be left on the pcb as it acts as a heat sink.
Certainly it works although the bright light is very diffused. I am not sure how you could use it as a headlight.
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soundwave

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my 50 quid light bulb from 2012 is still glowing :cool:
 
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thelarkbox

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You probably just need a nominally larger current pull to register with your flasher unit, if you check out ads for led indicator replacements you see they highlight the inclusion of a 'load resistor' which adds the drain required by the flasher unit to register/operate. the flasher is a bi-stable switch alone the led panels dont draw enough to start the 'flip/flop' perhaps?
 
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guerney

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Looks like the electrolytic capacitor has blown in the power supply module. Surprising to still see that these days. Use epoxy to glue the LEDs to a heat sink. You do need a current control module though to ensure the LEDs run properly.
Yep. Ordered this (link below) which looks useful to have around. It should fit inside the rectangular aluminium section I should be getting around to replacing the pallet wood plank with, that my battery mount has been bolted through for years, on the rear rack - it's a good thing aluminium doesn't have a sell by date, I've been meaning to position the battery closer to my bike's CofG on it for years.


...but then......


You probably just need a nominally larger current pull to register with your flasher unit, if you check out ads for led indicator replacements you see they highlight the inclusion of a 'load resistor' which adds the drain required by the flasher unit to register/operate. the flasher is a bi-stable switch alone the led panels dont draw enough to start the 'flip/flop' perhaps?
.... I used the Bafang headlight as a load with two of those very bright LED panels in parallel and.... Qapla'!! Very bright beeping and flashing! 10 seconds later, the lights went out. Burning smell. Dead 2A 36V cheap power supply. I should buy a set of resistors for this sort of thing. The power supply is glued together, no screws. I'll look at it later.

Update: The cheap 36V power supply now only supplies less than 20V.

Very bright while it lasted. 1/2273s ISO125 - I didn't want to risk a good camera, so used an old cheap phone I had lying around. For some reason it's also a camera.


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my 50 quid light bulb from 2012 is still glowing :cool:
They won't sell as many if they make them like they used to.


Certainly it works although the bright light is very diffused. I am not sure how you could use it as a headlight.
You might find a suitable lens? Use a cheap credit card diffraction grating magnifying glass cut to size, to form a beam? But they don't seem heatproof.

These diffusers are in good nick, can be made orange for dual sided and possibly very bright indicators, if I am sufficiently motivated to go the rigmarole.


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guerney

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This arrived this morning, will have a play at some point:

https://www.ebay.co.uk/itm/195759044419

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The borked power supply's voltage collapses at just under 20V. Casing is glued shut, no screws. Heat gun melts the case, doesn't soften the glue. Acetone melts glue, but also the plastic. I couldn't get a metal spudger in to pry the case open, I'll have to saw it through sometime.

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rigmarole
 
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guerney

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Good news is my cheap 3.5V - 36V(ish) adjustable power supply has recovered (powers two LED panels in parallel). Bad news is THE FLASHER OF BAFANG is dead! I've ordered some resistors. If sufficient enthusiam exists for installing foldaway ultra bright orange indicators on my bike's pannier rack, I'll get another 48V flasher.


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guerney

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At just over 48V.


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guerney

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guerney

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This arrived the other day - I'll test to see how much cooler these LED panels run at various PW Modulated signals... what those temperatures and frequencies are precisely (or thereabouts), I can use my shiny new Neoteck multimeter to determine. I'll run two panels in parallel continuously for hours at various voltages, and see if it dies. I'll do the same with the one above - can't be doing with a flash and magic smoke on the road. If I'm going to fit indicators, I want years of reliable operation.



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