SisterMaryElephant wrote:

DarkChessLord wrote:Azores, that wouldn't work because the heat is coming from the photons, not the panel itself.

Nope, the heat is coming from the heat sinks, attached to the LED drivers, inside the unit...

That is only true to the extent that these units are inefficient. If we take his word on the temperature reduction from this mod, that means they are very inefficient indeed (more than I thought).

DarkChessLord wrote:

SisterMaryElephant wrote:

DarkChessLord wrote:Azores, that wouldn't work because the heat is coming from the photons, not the panel itself.

Nope, the heat is coming from the heat sinks, attached to the LED drivers, inside the unit...

That is only true to the extent that these units are inefficient. If we take his word on the temperature reduction from this mod, that means they are very inefficient indeed (more than I thought).

Sorry, but *any* LED light with more than few diodes needs to use a LED driver and those drivers get HOT so they use heat sinks and/or fans. I think you've read a little too much LED light marketing propaganda which you should take with a grain of salt. There are a lot of LED myths and misconceptions that people believe for one reason or another.

SisterMaryElephant wrote: Sorry, but *any* LED light with more than few diodes needs to use a LED driver and those drivers get HOT so they use heat sinks and/or fans. I think you've read a little too much LED light marketing propaganda which you should take with a grain of salt. There are a lot of LED myths and misconceptions that people believe for one reason or another.

We're on the same page. 400W is 400w. It will heat up your tent the same no matter what kind of light you're using.

DarkChessLord wrote:We're on the same page. 400W is 400w. It will heat up your tent the same no matter what kind of light you're using.

Pretty much...with slight differences on where the heat is concentrated. With HPS most of the heat comes from the bulb and less from the ballast. With LED most of the heat comes from the LED driver and the power supply with very little coming from the actual diodes although those 5w diodes do get warmer than 1w or low-power diodes get.

Quick Note on LED system efficiency:

The heat eminating from the heat sinks of a LED system comes from two sources: LED emitters (diodes) and power drivers. LED emitters have been getting more and more efficient but even at their peak, today's LEDs are maybe 40% efficient. That means 60% of the power going to the LED emitter is actually converted into heat. Efficiency of a typical HID bulbs is in the low 20's. In other words, 75-80% of the power going to a HID system is converted into heat. So even though LEDs are almost twice as efficient as HIDs, the majority of the power (over 50%) is still being converted into heat.

The second source of heat comes from the drivers. Typcial LED driver efficiency is 85-90%. That means 10-15% of the power turns into heat.

As an example, let's take the SolarStorm 400W (Rough numbers based on specs):
- Input wall plug power: 350W
- Loss due to Drivers (say 10%): 350*0.1= 35W
- Loss in emitter (say 60%): (350-35)*0.6= 189W
- Total loss (heat generated): 35+189 = 224W
- Total LED system efficiency: (350-224)/350 = 36%

This means out of the 350W of power drawn from the wall plug, 224W is converted into heat, 126W is converted into light. You may see slightly better or worse total system efficiency numbers with other LED systems but in the end whether the total system efficiency is 30% or 38% you still need to remove over 200W of heat out of the system. Some systmes may "feel" cooler due to positioning of heat sinks, fans speeds etc.. but 200W of heat will elevate the temperature of a tent at the same rate regardless of where it's coming from.

In comparison, a typcal 400W HID:
- Input wall plug power: 440W (includes ballast)
- Loss in ballast (assuming high efficiency digital ballast): 40W
- Loss in bulb: 400W*0.78 = 312W
- Total loss = 312+40= 352W
- Total HID system efficiency: (440-352)/440 = 20%

This means out of the 440W of power drawn from the wall plug, 352W is converted into heat and only 88W is converted into light.

Of course aside from overall efficiency, the key advantage of LEDs is the spectrum.

I'm sure the math is correct there but, by those numbers a SS400w LED light *should* yield 16% more than a 400w HPS light and that doesn't seem to hold up based on yield comparisons of a 600w HPS vs the SS800w (assuming the difference is still 16%) when using a 1g/w baseline, which isn't unreasonable, for the HID grows. By that 16% number the SS800w should be yielding 750 grams dried and the SS400w (output 315w LED) should be yielding about 365 grams. Why is that?

day 17 of 12/12 - sorry about the low quality photos - i think the flash on my camera washed everything out.

Forgot to mention that everything seems fine now with the lamp closer (~18" now). Just speculating here but maybe now that they are in flower they can handle it. It never was an issue for the auto, just the jamaican dreams.

day 24 of 12/12
well, i stressed my grow out a little this week. I left for five days and rigged a little drip system to keep the reservoir topped up. But something went wrong and i lost pressure so when I got home the rrservoir was bone dry. I watered right away - also from the top - and things have stabilized but it wasn't pretty and i'm disappointed that i let it happen especially because it could have been totally and easily avoided if I had just spent the money for the auto water system ($50) that's on a float switch.

Great journal azores! I'll be watching to see how this one turns out!