Comparing 6 bright green LEDs at 5uA and 2mA

A project log for Designing a solar harvesting blinking gadget

Based on earlier solar harvesting projects I wanted to design a solar harvesting gadget

jasper-sikkenJasper Sikken 05/20/2021 at 19:390 Comments

Because I want the brightest flash on my solar harvesting blinky with Lithium Ion Capacitor I have ordered 5 green LEDs from Farnell.  I have tested them at 5.6uA DC current and compared to InfiniLED which takes 5uA on average from the battery. 

InfiniLED blinks with 1 ms long pulses at 35Hz which is supposed to perceived brighter than with DC current.

The camera doesn't capture brightness differences well. But I would rank the brightness like this

  1. InfiniLED
  2. LT CQBP-KYLY-36-8E8G, 857mcd@10mA, 0.66 euro
  3. 150141GS73113, 1250mcd@10mA, 0.20 euro

So the blinking InfinLED indeed looks brighter than the LEDs with DC current. 

In the next test the current is 2mA dc.

I see little difference, I think 150141GS73113 looks brightest. Interestingly it is the cheapest of all, and it doesn't have the highest specified luminous intensity, so that datasheet parameter is not something you can just believe.

I plan to adjust the LDO in my solar harvesting blinky to about 2.45V and use the 150141GS73113 and set LED current to about 2mA using a low value resistor to keep the losses in the resistor low.