Help needed adjusting and tuning a high power COB

2 posts / 0 new
Last post
Cuprani
Offline
Last seen: 1 week 6 days ago
Joined: 10/14/2020 - 11:45
Posts: 17
Location: Netherlands
Help needed adjusting and tuning a high power COB

I’m building my own work light, and would like to have some advice adjusting and tuning the COB.

Specs of the driver:
1200W CC CV Buck Boost Converter
V(in): 8-60V
V(out): 12-80V
Max power output is Vin x 20A
Because I use a 16V battery my max power output is (16×20) 320W
52V that is 6,15A 56V that is 5,7A

Specs of the COB:
Samsung SPHWHAHDNM251ZR3D2

The COB is rated at 1600 mA // 52V and then produces about 13000 lumen @ 1,6A.
Max current is about 4140 mA. According to the “forward current / forward voltage” -chart that is around 58V

What determines the maximum safe operating power?
Can I just crank it up to the point of 58V/4140mAh and check if the CPU coller doesn’t get to hot?
Or should I not exceed the 54V for a longer lifetime regardless the temperature?

According to the voltage/temperature chart the temperature is even lower at higher voltage, but I suppose that only applies up to a certain point.
I’ve tested it around 54V fot 30 minutes, and it doesn’t heat up at all.
I can lay my finger at the CPU plate right next to the COB, and it still feels very cold.
The heatpipes of the CPU cooler do not exceed the 25°C (77°F).

Edited by: Cuprani on 11/20/2020 - 15:23
Robin Dobbie
Offline
Last seen: 17 min 53 sec ago
Joined: 04/30/2019 - 12:49
Posts: 650
Location: Texas

I remember your original post about this and as I recall you were using a fairly decent thermaltake heatsink(the fan of which I recommended, and still do recommend, that you replace with something reliable that isn’t thermaltake).

Ultimately, you can’t know what the maximum wattage your led COB can handle, and maintain long life, unless you take its temperature on or near the emitter base to make sure you’re not exceeding the maximum limit. This is done with a thermocouple attached with thermal adhesive and shielded from light with kapton tape. Some brands even print out a location on the COB substrate that indicates where they take their readings. It’s not a hard line however, unless you get to the absolute maximum temps. Generally, the cooler an LED, the longer it will last.

Without measuring temps, I probably wouldn’t pump more than 150 watts into that light if it were in open air. But you’re putting it in some kind of closed lantern thing. So… less, maybe. And it depends on ambient temps.