For single LED beads, they looks very similar by appearance. Normally 1W LED use small sized chips(30 or 33 mil) while 3W Power LED use Bigger chips(42 or 45mil). And 5W LED use 4 chips of 1W chip. That is why 5W LED is much more expensive. Then how to tell the difference.
1W Power LED
1W Power LED are encapsulated with 30 or 33mil dies(Chips). So the chips inside looks smaller than 3W LED. Regular forwarded current for single 1W LED is 300mA or 350mA. Retular forwarded voltage for single 1W LED is 2.4V or 3.4V. Normally red and yellow led require lower voltage input which range from 2-2.6V while white/Green/Blue LED need higher voltage input range from 3-3.6V
3W Power LED
3W Power LED are encapsulated with 45mil dies(Chips). So the chips inside looks bigger than 1W LED. Regular forwarded current for single 3W LED is 600mA or 700mA. Regular forwarded voltage for single 3W LED is 2.4V or 3.4V. Normally red and yellow led require lower voltage input which range from 2-2.6V while white/Green/Blue LED need higher voltage input range from 3-3.6V
5W Power LED
5W Power LED are encapsulated with 4pcs 33mil or 45mil dies(Chips). Regular forwarded current for single 5W LED is 600mA or 700mA(2S2P pattern). Regular forwarded voltage for single 5W LED is 4.8V or 6.8V. Normally red and yellow led require lower voltage input which range from 4-5V while white/Green/Blue LED need higher voltage input range from 6-7V. But we can also customize the 5W LED with all 4 chips in series which will consume 300-350mA and 2.4*4 or 3.4*4V in voltage
But why 300mA or 350mA for 1W LED?
This is actually a very simple question. 350mA for High quality LED whle 300mA for Medium quality LED. Branded chips like Cree, Bridgelux, Epistar, EpiLED 1W LED will work on 350mA very well while some non-branded chips could only work on 300mA or lower. But for safety purpose, the whole industry almost widely product 300mA LED driver for them only. That is why you see most of Made in China drivers are 300mA for 1W and 600mA for 3W LED.
Difference between 1W 3W and 5W Power LED?
An simple introduce for LED Beads