LED wattage question, how do you count LED watts???

I learned how to count actual watts with CFL, but am confused about LED? I am not sure how to calculate the watts with LED. Do I count the watts the fixture uses, or what the fixture is supposed to be equivalent to HID watt wise? For instance...I use two Kessil H350 lights. They use 90 watts each, yet are supposed to be equivalent to around 350 watts HID each. So if I run them both together is that equal to around 700 watts, or 180?

Smokenpassout said:

I learned how to count actual watts with CFL, but am confused about LED? I am not sure how to calculate the watts with LED. Do I count the watts the fixture uses, or what the fixture is supposed to be equivalent to HID watt wise? For instance...I use two Kessil H350 lights. They use 90 watts each, yet are supposed to be equivalent to around 350 watts HID each. So if I run them both together is that equal to around 700 watts, or 180?

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IMO, forget about comparing them to HID, CFL's or anything else. Get a meter to measure the actual output of the panel and use 50-75W actual draw for veg, 75-100W for flowering per plant as your guideline, anything less you will likely be disappointed with the outcome. Those meters are cheap, even free through some hydro programs and will tell you exactly what your light(s) output is. Cheers and happy growing...

The Kessil H350 claims 84 watt power consumption. Assuming 20% driver and fan losses that works out to 67W each. So 134W is your total dissipation wattage ~ $4/W. That is the number you want to think about when comparing with an HID. For example a 600W HPS dissipates 600W in the bulb and about 60W in the ballast.

Not all LED watts are created equal so even if you do figure out actual wattage, you wont know how many photons those watts will create and how much will become heat. Based on that, I recommend buying LED lamps that are open about what emitters are in the lamp. If the lamp is using mystery LEDs, they could be only half as efficient as good emitters.

Still confused here totally

Smokenpassout said:

Still confused here totally

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just keep readin and you will catch up soon

basically like what was said earlier....

ignore what watts it says it is... usually on a lot of sites they will say "300W light- actually draw 240W" so its not drawing 300 watts... its only drawing 240... Leds usually arent driven at full power 100% of the time

With a pair of Kessil you are dissipating 135W. Unfortunately without knowing more technical details about the lights there is no way we can figure out how that will compare to an HPS. My best guess, that should be equal to about 150-200W of HPS.

This is about as detailed a look inside that Kessil have on their website.

http://reefbuilders.com/2011/03/29/dense-matrix-array-led-kessils-inhouse-version-multichip-led/#more-32091 - view of emitter board in smaller Kessil


States 21 emitters at ~1.5W each - really nice looking product which they've put a lot of work into. My gut say output numbers will be in the ball park of known top emitters - no one is going to be miles ahead here.