DIY LED Using 10 Watt Arrays

[mike31154]

Time for another update, this time due to a boo boo. Really should have seen this one coming, but kind of let it slide.

Been running the center rail with 4 whites & 5 blues on two dimmers. This means at full power of 1 amp per LED, the white dimmer would need to handle 4 amps & the blue dimmer 5 amps. Well within their rating & since I've got the voltage around 8 to 8.5 (a volt or two below the recommended voltage of 9 to 10), there's an added safety buffer with respect to current. So why would I run the both outer rails on only 2 dimmers? There are 5 Royal Blue & 4 10000K White LEDs on each outer rail. This means the RB dimmer handles a total of 8 LEDs & the 10000K dimmer deals with 10. If I were to run the RBs & 10000K LEDs at full power (0.9 amp for RB & 1.0 amp for 10000K), the RB dimmer would be at maximum rated current & the White would actually be over the limit by 2 amps. Clearly I know better, but I guess since I had the voltage down at 5 volts for the first year of running the LEDs, I kind of got complacent.

I recently replaced the 2 power supplies with slightly larger ones, my rationale being that with the extra power, the supplies should run cooler & safer. Not sure if this had anything to do with cooking the RB dimmer, but it wasn't long after this change that I noticed the RBs were very dim. I played around with the dimmer control & the LEDs hardly changed, just flickered. Photo tells the story, this is what a cooked dimmer looks like. The parts at the top of the photo are from a second dimmer that I patched in after finding the first one cooked. It started smoking a few minutes after I hooked it up. Might be able to save that one with a new MOSFET. What puzzles me is why the RB dimmer went & not the 10000K. After all it's running 2 more LEDs & it continues to soldier on with no sign of overheating. I have 5 dimmers on order & will be adding two to split the load & correct my faux pas. In the meantime, the tank's been looking a little whiter without the Royal Blues doing their thing for the last week or so. Livestock seems ok with it, but I'm anxious to get the RBs back on line.

[mike31154]

Originally Posted by daplatapus

Nice job Mike. I actually kind of like the 3 ribs on top.
FYI, when you have to wrap a curve like that, see if your supplier carries wiggle wood. It's a 1/4" plywood, but all the layers are oriented the same direction so it can roll up to something like a 4" diameter circle. Extremely useful, and you don't end up with those little curling edges that are always trying to straighten them selves like regular ply does.

Thanks for the heads up on the "wiggle wood". I'd never heard of that. Too late in the game for me now to rebuild the top, but certainly will keep my eye out for that stuff for future projects. I had also considered veneer, but that's pretty thin & actually quite costly compared to a piece of 1/8 " plywood. You can probably see the 'waves' along the bottom edge of the cover in the photos where the standard plywood didn't co-operate. I'll have to apply something along there to straighten it out, perhaps some gold coloured aluminum trim. The thing is starting to get heavy now though, with the larger heatsinks & cover.

[mike31154]

Took longer than I had hoped to get the additional dimmers I needed after cooking the one that was overloaded with too many 10 watt LEDs. They finally arrived yesterday & I've wired them in so each of the 3 LED rails now has 2 dimmers controlling the mix of white & bue. Previously I had 2 dimmers on the center rail, but only a single dimmer for each outer. Should have fixed that long ago, but let it slide until there was smoke. Bad idea.

At the moment the center rail has fired up & I'm still waiting for the outers to kick in which won't be for a few more hours. Once they're on, I'll adjust & take voltage/current readings. Everything should now be well within the 8 amp limit for each dimmer, even when I crank the voltage to near max. Vf for the LEDs.

This is how it was:



Here's the latest config. with larger power supplies & 2 more dimmers:



I've dispensed with the voltmeters since I wasn't really using them for daily monitoring. Since I don't have a controller & simply use timers to run the lighting schedule, I'll dial in a voltage, check that & current with my multimeter & see how things go with the livestock for a while. It appears nothing suffered too much during the past month with none of the Royal Blues running, so I'll just play it safe for a while & keep things running at a Vf that's comfortably below the max Vf for the LEDs.

[_Adrian_]

Nice Job...

I would change a few things though...
1.- Dimmers are a catch 22 - Loss of voltage as well as current limiting. You need to find a better solution as this is already getting complex and will impact the life of LED's and could be a potential fire hazard.

2.- Running LED's in series still means the same amperage draw just need more voltage. Ex.: 4 5v drawing 500mA each in series will require 20V @ 500mA but in parallel it would be 5v @ 2A. High draw situations the heat is generated.
The LED's im planning to use are rated for 9-12V at 900mA but will run 4 per string ( for a combined maximum voltage of 48V. This means one 48V 10A power supply can drive about 40x 10W LED arrays at 95% load.

3.- Move to a larger heat sink, loose the fans and gain back your hearing LOL

4.- Start looking at an light controller, whetever its off the shelf or Arduino based. This would allow you to recreate solar and lunar cycles and being able to fade in and out and recreate more other weather related events ( Ex: storms ). There's Tons of PWM controlled LED drivers that are fair priced, and readily available.

All this ends up reducing heat output, you'll end up extending the life of the LED, makes the system more stable and easier to use/maintain most of all

[mike31154]

Thanks for the input. Not sure how much of the thread you've read, some of the posts are quite long. The fixture's been running fine since April 2012 except for the one mishap which I kind of had coming by overloading one of the dimmers. I have added larger heat sinks & ditched the original smaller ones with fans. I don't want a light controller beyond the dimming controls that I'm using already. Don't see how adding a controller or rewiring to series will make my life simpler. It would mean buying new power supplies/drivers & rewiring the works! If I do another build, I will probably use a few of the larger watt LEDs with optics. Don't foresee any major modifications in the current fixture, it's working fine for me as is. Maybe good info for some one else who's embarking on a new build!

[_Adrian_]

No worries.
I will be soon posting a build log for my setup.
This will have a whole bunch of custom PCB's and multichannel controller / drivers...

[DSlater]

Mike

Do you get any noise from those power supplies?

Mine made a bit of noise ramping up and down at first, now after a year they are much worse. Feel like modifying them with my hammer. Just curious if yours were the same at half or less power.

[mike31154]

One of my power supplies has a built in fan, so that is audible, but normal. Other than that, they don't produce any noise. Solid state, so there really should be no noise, other than a transformer hum, but the transformers in these are fairly small, so shouldn't be audible.

[mike31154]

Originally Posted by _Adrian_

No worries.
I will be soon posting a build log for my setup.
This will have a whole bunch of custom PCB's and multichannel controller / drivers...

Cool, looking forward to a new build thread. Hasn't been much on the radar here of late. With the price of commercial fixtures continuing to drop, the DIY LED spirit is waning!

[mike31154]

In a couple of days this DIY fixture will have 3 years under its belt! Despite it being a parallel set up & all the 10 watt LEDs purchased off shore, there have been no failures to date. I've made several of modifications since April 2012, but essentially it's been doing its thing trouble free (after I added several additional dimmers to handle the load). I think it's safe to say this rig now owes me nothing. No bulb changes for 3 years, I haven't done the math, but if I was still running my MH/T5HO combo, there definitely would have been a few $$$s spent renewing them.

I will likely remove the supplementary 5050 RGB lighting strips & replace them with more powerful warm spectrum 5630 strips. It's cool to play around with the RGB colours, but they tend to drift in spectrum & the 'white' light created when all 3 colours are on, is not really all that white. One strip appears greenish, the other more blue. They certainly haven't been as robust as the 10 watt multi chips & seem to keep changing spectrum on me. I have a couple of UV 10 watt LEDs that I considered adding, but the livestock I have at the moment seems fine with the lighting as is, so probably best to not mess with it & keep it simple.