Can this headlight be upgraded with better LEDs?

[Cemoi]

Hi all,

I have a two AA battery Headlight from Bush&Müller (search for "B&M395" on this page), which I like because I was able to mount it permanently to my bike so that it would be hard to steal (tools required), and because it has a built-in reflector (which is compulsory in Europe).
It is only a light to be seen, not to light the road but it is OK since I use my bike only in cities, or during daytime when on tours.
I wonder whether it would be possible to make this light brighter by replacing the two LEDs by more powerfull ones.
Here is a picture of the circuit board which carries the two LEDs.
Please note that I am a total ignoramus in electronics, but I should be able to desolder the old LEDs and solder new ones.

 

[Szemhazai]

You can simply replace old leds by a new Nichia NSPW500GS-K1 leds.

look here :
http://www.cpfmarketplace.com/mp/showthread.php?t=177181

 

[Cemoi]

You can simply replace old leds by a new Nichia NSPW500GS-K1 leds.

Thanks. Do you mean I can replace both LEDs with Nichias? Will the light get hotter with these, and what will be the influence on runtime?
In a more general way, can any 5 mm LED in any light (be it a bike light, headlamp, or flashlight) be replaced with a Nichia?

look here :
http://www.cpfmarketplace.com/mp/showthread.php?t=177181

Unfortunately this sale is closed.
Do you know any other place where such LEDs can be purchased (preferably not 10 at a time, I only need two of them)?

 

[Szemhazai]

Do you mean I can replace both LEDs with Nichias?

Yes, any 5 mm white led can be replaced by these Nichia's

Will the light get hotter with these, and what will be the influence on runtime?

No and No, these new leds are only more efficient, power consumption is on the same level and the thermal emission is much lower.

 

[Lynx_Arc]

Thanks. Do you mean I can replace both LEDs with Nichias? Will the light get hotter with these, and what will be the influence on runtime?
In a more general way, can any 5 mm LED in any light (be it a bike light, headlamp, or flashlight) be replaced with a Nichia?


Unfortunately this sale is closed.
Do you know any other place where such LEDs can be purchased (preferably not 10 at a time, I only need two of them)?

I think you can buy a pair of nichia photon clones at dealextreme for under $4 that have the GS leds in them there is a thread talking about people buying the coin cell keychain lights just to harvest the nichias from them for upgrades somewhere. That is currently the only source I have seen listed in the last few months for them other than buying direct from a distributor and ordering a bunch of them.

 

[Cemoi]

there is a thread talking about people buying the coin cell keychain lights just to harvest the nichias from them for upgrades somewhere

It is this thread (see posts #95 and 97).
But I am a bit reluctant to buy lights (whatever their size and cost) to trash most of their components.

 

[LEDninja]

You can use UNCUT SMJLEDs for lights without reflectors.
Available in 1 pack
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_52_82&products_id=755
5 pack
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_52_82&products_id=758
10 pack
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_52_82&products_id=815

-----

You can also use cutdown SMJLEDs for lights with reflectors.
Available in 1 pack
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_52_82&products_id=754
5 pack
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_52_82&products_id=757
10 pack
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_52_82&products_id=814

 

[Cemoi]

Thanks LEDninja for the links.

Does SMJLED = Nichia?

You can use UNCUT SMJLEDs for lights without reflectors.
(...)
You can also use cutdown SMJLEDs for lights with reflectors.

What is the difference between "uncut" and "cutdown"? The pictures on The Sandwich Shoppe website are so small that I can't see any physical difference.
And what does "4 die" mean?

 

[LEDninja]

MJLED/SMJLEDs are not made with NIchias
Most older 5mm LEDs are made with a .25mmx.25mm chip or die. They can take 20 mA drive current.
Nichia was the 1st to make them and they are more rugged than the Chinese copycat clones. Can take 30 mA in the Arc AAA & 40 mA in Dorcy AAA gen 1 & 2.
Nichia improved brightness over the years with better technology. BS 3 lumens > CS 5 lumens > DS 9 lumens at 20 mA.
The Chinese can not keep up with the technology improvements so they put more chips or dies inside the LED case to make them brighter. So there are 1, 2, 3, 4 die LEDs. 3, 6, 9, 12 lumens at 20, 40, 60, 80 mA.
Nichia had to make a brighter LED so they also made a 2 die LED the GS 11 lumens at 20mA.

A looooong time ago (1999/2000?) MJ (ARCmania on CPF) discovered by flattening the top of an LED more light goes sideways into a reflector making for more throw. Together with the owner of LEDcorp they came up with the Turtlelight/Dorcy 4AA 1 LED floating lantern (cool blue).
Later he found a 'big die' LED with a low Vf that can be run off 2AA batteries without a boost circuit. When he ground down the top of the LED it became the MJLED.
Later he came across the 4 die LED which is brighter than the MJLED, and called the new version Super MJLED which is a mouthful so everybody refers to it as the SMJLED.

CUTDOWN is designed for lights with reflectors.
Since the light you linked to does not have a reflector, you need to get the LEDs with the domed top or UNCUT version.
If you can I think the Nichia GS is the better choice (longer LED lifetime & more efficient). But if you have trouble getting them the uncut SMJLED should also work.

 

[Cemoi]

Thanks for this detailed history on 5mm LEDs, some CFPFers are real experts!

Nichia had to make a brighter LED so they also made a 2 die LED the GS 11 lumens at 20mA.

How can I know what the current in my bike light will be, and hence how much light will the LEDs output?

Since the light you linked to does not have a reflector, you need to get the LEDs with the domed top or UNCUT version.

As this is a "to be seen" light I'd appreciate that part of the light goes sideways, so I could combine one uncut and one cut in the same light.
How much spill do the Nichia GS have?

 

[LEDninja]

How much spill do the Nichia GS have?

Not much. Hotspot seems bigger but not the spill.
The E01 has the GS, the others have the BS in this review.
In addition to slightly brighter note the less blue tint.
http://www.candlepowerforums.com/vb/showthread.php?t=196564

 

[Cemoi]

Yes, any 5 mm white led can be replaced by these Nichia's

After trying it, I'm afraid it is not true.
I first tried to replace only one of the original green-yellow LEDs with a recently purchased Nichia GS: the Nichia did not light up, only the original LED was lit.
Then I replaced the other LED as well, so I had two Nichias. This time they do light up, but they are very dim, in fact the light is now less bright than it was with its original LEDs.
I'm afraid it has to do with the higher Vf as warned by Doh!Nut in this thread (post #8). Could someone explain me what happens exactly: why does it work with two Nichias (although very dim) and not if I swap one LED only?

 

[ZFlash]

Hmm, how to explain not in my native language, I'll try...

You've got two LEDs in parallel in your lamp. With differnet leds you've experienced the different Vf (voltage forward) needed to be conductive. The original led seems to have a lower Vf than your new Nichias, so it lit up but the Nichia didn't, because the 'resistance' at a Vcc lower than 3 Volt is to high. The problem is your 2 AA batteries: You've got only 3V to deal with, which imo isn't enough to reach the Vf needed to power enough mA's for two Nichias.

I think you would need to add a circuit to boost up your voltage, maybe you're able to mod some diy-stuff from dealextreme or kaidomain...

 

[Christexan]

You mention the original "green/yellow" LEDs, if they truly aren't white LEDs (blue/phosphor mix), but are actually a green or yellow LED or combination, then they are a totally different composition (and voltage requirements). Only if they are truly just an "off-white" white LED, will you be able to "swap" them one-for-one.

 

[Cemoi]

Hi all,

I have completed this project at last, using the circuit described on this page. The resulting circuit board can be seen here (the transistor is on the other side).
The difference in brightness is incredible: the original, very dim (green-yellow) LEDs made this light barely a "be seen" light, whereas the Nichias powered by this circuit are very bright and even able to light objects in the distance. Not as powerful as the amazing DIY lights (using power LEDs) shown by others on CPF, but a huge improvement over the original version of this light.
The LEDs (in series) get about 18 mA with freshly charged NiMH batteries, and the whole current draw on the batteries is around 55 mA.

 

[rufusbduck]

Way to persevere! I enjoyed reading the tale of your enlightenment, especially ledninja's sidebar on smjled's. Thanks to all.