Chinese Black Box LED Current Draw impact on wavelength?

[mrsofty]

HI,

 

So I just received an LED light I bought off Amazon. It claims to have 455NM diodes so I thought I would give it a try.

 

Problem is that it only seems to draw 90 watts at full power (1.6 watts per LED), actually 85 watts without the moon lights. I know the chinese 165w lights usually draw much less but I thought it was around 110watts.

 

Question is.. would the low current draw change the spectrum at all? and would 85 watts of chinese LEDs be enough for my 60 gallon cube (24" x 24" x 24")?

 

Thanks,

Matt

 

 

[Horerczy]

If the spectrum shifts it's too small to really matter.

[Chris S]

The only way to know for sure if it's enough light is to get a par meter

[evilc66]

You have nothing to worry about with regard to spectral shift. For colored LEDs, you may see deviation in the +/-2nm range, but that's not enough to make an appreciable difference, and this deviation is only seen at the extreme ends of the current range. White LEDs may shift +/- 100-200K, but again, it's not enough to make a difference. And really, it's not the current that's causing the shift, but the relative heat produced by running that current through the LED.

[mrsofty]

Thanks for the input. So is 90 watts enough for a 60 gallon cube? Not really sure why the power is so low, I opened the unit and it has 2 70 watt controllers plus a 12 watt for the moons. This should max out much higher.

[evilc66]

This is not uncommon. It's a pretty common practice of Chinese sellers/manufacturers to fudge the numbers a bit by advertizing fixtures like this with the total "potential" wattage based on what the LEDs are capable of, in this case 56 3W LEDs. Seeing as wattage is voltage times amps, the total wattage draw at the wall will be defined by the output current of the drivers, and the number of LEDs connected to them. Just because the driver states 70W, doesn't mean that it's drawing that much. The reason you are seeing the draw from the wall being a lot different from other fixtures of a similar style is that each reseller may spec their fixture slightly differently. In your case, the reseller got a low output current compared with other similar fixtures.

 

Will this be ok for a 60g cube? That really depends on what you are looking to keep. For a softie/LPS tank, you should be ok, even with sps higher in the middle of the tank. If you were looking for a heavy sps setup, then you will need more power. You can either double up and get another fixture, or return what you have and go with something with a little more grunt.

 

This is why you really need to stick with reputable resellers that offer a known product. You do get what you pay for.

[mrsofty]

Thanks Evil. Makes sense, the two larger drivers say 480mA I wonder if something in the 700mA range would have worked better?

[jedimasterben]

Thanks Evil. Makes sense, the two larger drivers say 480mA I wonder if something in the 700mA range would have worked better?

Depends on what you mean by better. It will give the LEDs more power and increase heat by a pretty good bit, and depending on the design, more than likely cause the fixture to fail very prematurely. Most of the cheaper fixtures are made using only fans over an MCPCB with no heatsink. If you plan on doing anything, I would send back that fixture and purchase one that is what you need.

[mrsofty]

Yup. No heat sink.