Single LH351D with Dr. Jones question

[thefreeman]

90 or 70 CRI ? 90CRI LH351Ds have a lower Vf and so will pull a higher current in direct drive.

Samsung LH351D color testing

Output in a sphere. Strange that the output tapers off at 6A while in TA’s test on the CRI70 version went much higher. Maybe my reflow wasn’t perfect. At least the performance up to 4A is very good. [image] [image]

Samsung LH351D color testing

CRI70 version of the LH351D topped off at about 6 amps with two different heatsinks and fans. The heatsink shouldn’t be to blame since I also tested an XP-L2 CRI70 and it went nicely all the way up to 10A with more output and better efficacy than in TA’s test. No idea about the binning of my sample since it came from Kaidomain. Could also be the nondescript MCPCB I used for the Samsungs. Kaidomain Cu DTP for the XP-L2. [image] [image]

As you can see efficiency goes does down as current increases so you can’t do a rule of three to estimate lumens.

Estimating current in direct drive isn’t easy because a bunch of resistances influence it. You can try myDD calculator , you wont get very accurate estimations but it should help you understand how it works.