XP-E2 vs SST-20 – Which Budget Emitter Wins?

[emma1 (emmmma)]

While organizing my inventory recently, I took the opportunity to test a few often-overlooked “veteran” LEDs with an integrating sphere. Here are the results (driven by a constant current of 350mA, in a 25°C environment):

Cree XP-E2 R3:
Luminous flux ≈ 112 lm
Color temperature ≈ 6100K
CRI ≈ 71
Luminous efficacy ≈ 108 lm/W

Luminus SST-20 4000K (90 CRI):
Luminous flux ≈ 138 lm
Measured CRI ≈ 92 (Excellent color rendering)
Luminous efficacy is slightly lower, around 96 lm/W, but the viewing experience is much more comfortable for everyday use.

Although the XP-E2 is older, its efficiency remains high at low current, making it suitable for small copper contacts or small AA direct current flashlights; the SST-20 high CRI version is a comfortable choice for EDC flashlights—especially for reading documents and identifying objects at night, where the colors don’t appear grayish.

None of them are particularly new or high-end, but they are cheap, easy to solder, and reliable. If any fellow enthusiasts have tested other less common models, please feel free to add to the list!

[QReciprocity42 (efficacy ≠ efficiency)]

@emma1

Luminous efficacy ≈ 108 lm/W

@emma1

Luminous efficacy is slightly lower, around 96 lm/W

@emma1

Although the XP-E2 is older, its efficiency remains high at low current,

Careful–you meant to compare efficacy! High CRI + low CCT tend to have much lower spectral efficacy than low CRI + high CCT; given the small system efficacy difference of only 108 vs 96, it is reasonable to conclude that the high CRI SST20 is more efficient. That is, SST20 converts more input power into radiant power, which is slightly less visible due to high CRI.