Cheap Replacement Led's

Chris_83

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Does anyone know where I can get a cheap replacement 4.5V led for my flashlight that ships internationally? The board is optional. I only need the actual led. If necessary, I can solder it on the old board. I found some on ebay but they cost about $17 or more with shipping which is more than the cost of what I paid for the flashlight! The LED's must only cost a few cents to produce. Your advice would be appreciated.

Kind regards
Chris
 

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Chris_83

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Thank you all very much for those links. I will check them out.

Kind regards
Chris
 

Chris_83

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Thank you for the extra links!

I will be using 3xAAA alkaline batteries (3.5-4.5V). I want a bright led but don't want to drain the batteries too quickly. Do you have any idea what lumen output is the norm for this flashlight? On the list I can see 155 Lm at 350 ma and 280 Lm at 700 mA. My guess is that this originally had a 155 Lm diode or lower for longer battery life.

Kind regards
Chris
 

desert.snake

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Very similar to this one

Do you have such control?
High > Mid > Low > Strobe > SOS<middle<low<sos<strobe<...


It will put out as much power as the driver will allow. I don't know how much it's programmed for, but it's unlikely to be very much. You can choose any diode. There in the filter there is a lumens / watt parameter, you can choose the largest one for greater brightness, for example this one
or 1 of these 3

Oh, do you want it to shine with white light like a luminous center lamp or like an incandescent bulb?
 
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Chris_83

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Thanks for the help. It just has 1 mode ON/OFF. It has a lens that can be pulled out to narrow the beam to make it smaller and brighter. I want to keep the original specs if possible. It needs to work with 3xAAA (4.5V max) I will check out the other links. Thanks again!

Kind regards
Chris
 

desert.snake

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Thanks for the help. It just has 1 mode ON/OFF. It has a lens that can be pulled out to narrow the beam to make it smaller and brighter. I want to keep the original specs if possible. It needs to work with 3xAAA (4.5V max) I will check out the other links. Thanks again!

Kind regards
Chris
Most modern LEDs from well-known manufacturers will shine brighter than the original. And then carefully look at the light temperature. You need 5700K and more - 6000K, 7000K.... then it will be ~ similar to what you had - cold white light.
Designated as CCT
1672955909074.png
 

LEDphile

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More lumens at a given drive level (power - voltage times current) means a more efficient LED and longer battery life for the same output. And no white LED is going to be happy running directly from a 4.5V power supply (the higher current parts should be OK to run off 3 alkalines in series due to the internal resistance of the cells). If you aren't going to add any sort of driver or dropping resistor, you'll want an LED rated for at least 2A to avoid frying the LED with fresh batteries (or lithium cells).
 

Chris_83

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Thanks for the advice. The 3xAAA 4.5V first goes through a driver board inside the flashlight before it reaches the led. So I guess that would offer some kind of protection.

Kind regards
Chris
 

Chris_83

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Thank you all for your help. I have learned a lot from this thread. Here is an update.

I tried to purchase from a USA site and a European site and they both wanted about $30 shipping for LED's costing less than $5. That wouldn't be worth my while because the flashlight is only worth a few dollars.

So I tried Ebay again and instead of searching for "led flashlight replacement", I searched for, "Led pcb" and I got lots of hits that were far more reasonably priced. So I ended up getting 2 bright led's complete with the board for about $4 ($2 each). I am guessing that they are similar to the original specs, although not as good as the others that have been recommended.

Thank you again for all your help.

Kind regards
Chris
 

Dave_H

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Thank you all for your help. I have learned a lot from this thread. Here is an update.

I tried to purchase from a USA site and a European site and they both wanted about $30 shipping for LED's costing less than $5. That wouldn't be worth my while because the flashlight is only worth a few dollars.

So I tried Ebay again and instead of searching for "led flashlight replacement", I searched for, "Led pcb" and I got lots of hits that were far more reasonably priced. So I ended up getting 2 bright led's complete with the board for about $4 ($2 each). I am guessing that they are similar to the original specs, although not as good as the others that have been recommended.

Thank you again for all your help.

Kind regards
Chris
Your flashlight looks very similar to low-cost 3xAAA "zoomie" lights typically available $10 here OTC, and sometimes am able to be 2-pack for under $10. Yours should take an 18650 and I use a PVC tube spacer. Running on 3xAAA is not viable for very long at high brightness/current.

You would not specify 4.5v for the LED, it would be power e.g. 5W; 4.5v nominally feeds the driver circuit but will go lower as cell(s) run down.

On high (these specify 350 lumens) I measure about 1.2A at 4v (Li-ion) so consumes about 5W. If you want similar brightness, 1W or 3W LEDs will not be sufficient.

I have not figured out how to get mine apart without damage, and no real need to so far other than curiousity. Mine have five modes: high/mid/low, flash and SOS. Cycling modes is annoying.

I like fixing things also but can't see paying excessive prices for replacements. Perhaps you could salvage LEDs from something like a 12v automotive LED spot/worklight, if you can find a suitable one. Many use "3W" LEDs although driven at lower power for better lifetime. Your present board could overdrive them though unless there is a way to reduce drive current, if it is as high as I think it may be.

Missing spec for replacement LED is beam width which will affect the beam characteristics. Perhaps someone knows what it should be for this type of setup with the lens, I don't.

Dave
 

Dave_H

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Does anyone know where I can get a cheap replacement 4.5V led for my flashlight that ships internationally? The board is optional. I only need the actual led. If necessary, I can solder it on the old board. I found some on ebay but they cost about $17 or more with shipping which is more than the cost of what I paid for the flashlight! The LED's must only cost a few cents to produce. Your advice would be appreciated.

Kind regards
Chris
BTW what type of drive circuitry does the LED board use? I can't see much besides the LED on the PCB top side. What's on the bottom?

Dave
 

Chris_83

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Dave, thank you for your reply. Yes its the low cost 3xAAA "zoomie" lights you describe. I got a few from China very cheap a few years ago. They all came with the plastic tube 1850 Adapter. However, I have never used 1850 batteries in this flashlight. All the 1850 batteries I have don't hold their charge very long which means I can't use the flashlight at short notice unless I am regularly recharging them. I find that regular AAA's are much more reliable.

Now I come to think of it, they did all have the 3 modes you describe which I found very annoying. So I modified the circuit to just have ON/OFF at full power. I describe how I did it here on page 2.


This is the driver circuit board. Moving the blue wire from A to C will give you ON/OFF only. Probably this bypasses the board. But honestly, I only think the function of the board is for the the strobe and half power function. I have used the flashlight with the modified board for a few years without any problems. Only now do I need a new led.

Kind regards
Chris

Flashlight Circuit.jpg
 

Dave_H

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Interesting Chris, thanks. I did some tests on a couple of these using variable power supply. Starting at 4.6v (0.9A) current decreased with voltage, down to 3.3v (0.3A). This indicates driver behaving as a dropping resistor, not too efficient using any type of cell(s). As currents and voltage differences are not that high, this works out and is cheap.

If you replace the board and LED, you might manage to get a driver which is linear constant-current (e.g. AM7135 type) for more constant brightness; or switching type with some runtime improvement.

I've never tried replacing a high-power SMT LED. Older style "pill" with flat leads sticking out looks not to hard; never ones with pads on the bottom looks a bit trickier.

A related aside, just read a PCB article on high-temp solder for power LEDs (>1W) using 80% gold (!), 20% tin, probably does not apply to cases like this (I hope).

Dave
 
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