killed some 35K's ...

In this post I created a POP-based, hand-built module for a 9-5mm LED head, which I used in a 6P from a 168S LiIon cell. Due to being POP-based, this LED light is my most used light within my house, usually at a low level. However, sometimes I go to full-bost level, and sometimes my daughter gets a hold of it and without knowing she gets the light to full-power as well (my POP is setup for LOW then HIGH).

I liked the module so much that I added an external grounded spring to allow it to work on my favorite host, the G2. Yes, the module is not pretty, but it works awesome:






As shown in the post linked above, the light draws about 61mA to each poor LED, which I though was "OK" for occasional use. Boy was I wrong - this is how it looks after 6 months of use (this is on LOW):


First one LED, then the second, then the third .... The "dying" LED first starts to flicker on "HIGH", but works OK on low, until eventually it does not light even on LOW

I suspect that the LED's die "open circuit" so the remaining LED's get even more current (they are all wired in parallel), so it is only going to get worst with time.

Although expensive, since this is my MOST used LED light, I am going to replace the LED's with the uncut MJLED's, which can take about 100mA, which is significantly higher than the 60mA or so that the circuit can provide. Hopefully the LED's will then last a looooooonnnngggggg time

Will

I finished the project last week and my G2 now has 9x SMJLED's in it. Overall current drain from the battery is about the same, but the brightness went up significantly. In fact, it is high enough now that even on the lowest level for the POP, it is too bright to navigate around the house at night with dark-adjusted vission . On the positive side, on HIGH, my new G2 is absolutely brilliant

Will

Oh no!!!! My babies, you've killed them!!!


Just kidding... now we have 40K LEDs available, you might want to use that as an excuse to upgrade :nana:

Problem is, though, that they are only rated for 20mA drive current.. so yup, there is a real risk that they can go kaboom. Nice module you have there, though!

I'm kinda impressed that the LEDs hold up as well as they do really. I mean you have driven the LEDs at 3 times spec (and even more as more LEDs die) in a light that you have used a lot for the past 6 months and you've only lost 3 of them

Robban said:

I'm kinda impressed that the LEDs hold up as well as they do really. I mean you have driven the LEDs at 3 times spec (and even more as more LEDs die) in a light that you have used a lot for the past 6 months and you've only lost 3 of them

Click to expand...

Yes, I agree. They lasted longer than I expected, although you should know that I have not been running the LED's in HIGH for these last 6 months, more like 80% LOW and 20% HIGH. Once one of them died, the other ones seem to have died quickly. With the MJLED's that I am using, I "should" not have that problem since they are being driven below their 100mA max rating

Will

KevinL said:

Oh no!!!! My babies, you've killed them!!!


Just kidding... now we have 40K LEDs available, you might want to use that as an excuse to upgrade :nana:

Problem is, though, that they are only rated for 20mA drive current.. so yup, there is a real risk that they can go kaboom. Nice module you have there, though!

Click to expand...

Yes, the new 40K's are still not going to do as well as the MJLED's. I think that I will stick with my current LED's for now

One thing I noticed last night is that compared to other 5mm LED's, the new MJLED's that I am now using in my module have a noticeable blue tint to them, unlike the 35K's which were more "white" to my eyes - there is always some compromise to be made

Will