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.