JoeyV
Well-Known Member
Got a pic of your light strip? Also, how did you wire them up? Series or parallel?When balancing up front cost, performance, and ease of construction I picked these:
http://www.aliexpress.com/item/Wholesale-10pcs-of-lot-30W-LED-Chip-for-Floodlight-Flood-light-Warm-Cool-white-6000k-6500k/2011319079.html
http://www.aliexpress.com/item/400W-S400W-36V-11A-LED-Switching-Power-Supply-36V-11A-85-265AC-input-CE-ROSH-power/1544392301.html
Add a piece of flat stock aluminum, thermal adhesive, a lamp cord, and 2 splice connectors per chip and you have a very high power light strip, perfect for making a grid for optimal distribution. I don't over power them, I run 15 on 400w.
I'm actually waiting on my second order of these now.
I've been looking at the specs on that power supply, and what's pictured isn't what's specified in the ad. There must be a 36vdc version that isn't listed on the page.
Also, you say you're running fifteen 30w COBs off of that one supply. They must've listed the specs incorrectly on the COBs as well. It's listed at 1500mA.
34vdc(fVmax) * 1500mA = 51w.
1 - 30w COB @ 34vdc = 30w/34vdc = 882mA.
15 COBS @ 882mA = 15 * .882A = 13.23A.
The supply is rated at 36vdc @ 11A = 396w. It has an efficiency rating of (approximately) 82%. So at full load it's drawing 483w. It appears that you'd be losing 87 watts to heat, assuming the supply actually delivers the full 400w output.
The stock strip of aluminum will likely get hot, depending on it's length and thickness. Cooling fins help dissipate the heat by giving more surface area for air to heat up around. But it doesn't sound like you've got any on your strip. You could attach heatsinks behind the COBS on your strip. That should help keep the strip and the COBs cooler. They don't have to have fans. Though a fan blowing over the strip will also help cool things down.
If you're running in parallel, the COBs furthest from the supply will be seeing a drop off in voltage, depending on the gauge of wire your using. Using 18 awg wire would result in a 2% drop down to 33.32vdc @ 1 meter away from the power supply. 12 or 14awg wire will reduce the drop off to below 1%. Placing the supply in the middle of the strip will also reduce the % of loss as would using stranded wire. How much I don't know, but some for certain.
I could be wrong in my calculations however... I'm using basic Ohm's Law and some wire gauge calculators online. I have no experience with these new high powered LEDs. It's all just theoretical for me right now.
I'm still learning about COBs and have a bunch of cheap Chinese stuff for experimenting on order.
To anyone, please feel free to correct me if I'm wrong about any of my calculations. And by all means, expound on anything I might have gotten right or wrong.