Month: March 2017

A Comparison of Lumen Output at Common Wattages

Tonight I wanted to see just how close most of the popular COBs are in terms of lumen output at various wattages, so I punched some numbers into the manufacturer product selection tools and compiled a list. All results are calculated at a case temperature of 55 degrees Celcius (except for the Luminus CXM-22, for which I estimated Tj to be 85 degrees in order to have a case temperature as close to 55 C as possible). A color temperature of 3500K and 80CRI was used for every COB.

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How to Find the Right Heat Sink for Your COB LED

Matching your COB to a heat sink is one of the most difficult parts of designing your own COB grow light. Unless the manufacturer of the heat sink actually specifies the wattage you can get away with running, you’re left to do the calculations yourself. Luckily, there are tons of heat sinks available now that come pre-drilled for your COB or board, and are rated, in plain English, for their power handling ability. You might see smaller pin-fins (120mm or so) that are rated for 50 watts of power, larger pin fins at 140-150mm rated for 75 watts, or even bigger sinks that are 160mm+ and rated for 100W.

That being said, you might be a glutton for punishment and have a burning desire to source your own heat sink, or figure out if the one you’ve got kicking around will work. Fortunately, like most things in the DIY LED world, we can figure this out with a little research and perseverence. Fair warning though, this is pretty dry stuff.

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