LED Strip Build Questions

[algebraist]

Okay, suppose we go with the reasonable theory that if there isn't enough voltage, then the strips won't light up, but it can't do any damage. Is the only other explanation anyone can come up with for me is that I had a bad EB strip, and the replacement strip also happened to be bad (in a very similar way)? That's all I can come up with, and it seems so unlikely.

Further circumstantial evidence against that: the strip in question is the last of the nine -- at the negative end of the series (i.e. the negative DC wire from the driver connects to that strip). Not some random strip in the middle. Suspicious.

 

[algebraist]

Correction: The problem strip is the first of the nine -- at the positive end of the series.

I just bypassed it; runs fine with eight strips.

 

[Chip Green]

Is it possible that the way the diodes are "wired" internally on the board, that its causing only some to illuminate when the max voltage is reached? Can you bypass a different strip?

Edit: Wait, none of the strips are lighting, or you are getting single diodes out on a single strip?

 

[algebraist]

They light; two diodes out on one strip. Pictures and more detailed explanation (of the bizarre failure behavior) on this thread: http://rollitup.org/t/bad-eb-strip.942178/

Barring an explanation other than 1) bad strip and bad replacement, or 2) underpowered driver somehow damages strips, I'm thinking that in any case dropping down to 8 strips is the right plan. Given the 3 temperature / voltage points that Bridgelux supplies (50C, 22.1V; 85C, 20.2V; -40C, 25.6V) you can graph a "best fit" curve to those numbers (technically it's a quadratic) and use it to estimate the voltage requirements at various temperatures:


At 15.5C (which is about 60 degrees F, the coldest I ever expect my tent to get -- dead of winter, lights have been off all night) the strips should require about 23.7V. Multiplied by 9 that's 213.3V, still under the driver's max of 215V, but with very little wiggle room. So if -- as someone suggested in an earlier post -- the drivers might sometimes be a little below spec, or if the behavior of the strips doesn't match my best-guess curve above, then there could be a morning in February when the timer clicks on for day, but the lights stay off. How unpleasant.

 

[Serva]

From my experience the MW driver run higher than written on paper. The numbers are what they really will give you, otherwise alot of calculations would have failed in the past.

Especially with your calculation, showing the voltage should be enough (you don't have 15.5C right now), and one panel running properly with 9 strips, I still suspect the strips to be damaged somehow. So just complain, get replacement, and try again.

Like Chip Green said, did you tried to bypass a properly running strip, including the first one to your circuit of 8 strips?

 

[DirtRunner]

A couple of the Samsung F-series Gen3 finally showed up at Digikey, although in very limited quantity and selection. Here is the 3500k, 560mm, double-chip version:

https://www.digikey.com/product-detail/en/samsung-semiconductor-inc/SI-B8U521560WW/1510-2222-ND/6624006

8800lm, 171 lm/w, $27 each (much cheaper as quantity increases).

Digikey currently has the 5000k also.

 

[nogod_]

Still waiting on the 56cm single row 3000k but thanks for the update this is promising!

@Randomblame

A couple of the Samsung F-series Gen3 finally showed up at Digikey, although in very limited quantity and selection. Here is the 3500k, 560mm, double-chip version:

https://www.digikey.com/product-detail/en/samsung-semiconductor-inc/SI-B8U521560WW/1510-2222-ND/6624006

8800lm, 171 lm/w, $27 each (much cheaper as quantity increases).

Digikey currently has the 5000k also.

 

[jonsnow399]

A couple of the Samsung F-series Gen3 finally showed up at Digikey, although in very limited quantity and selection. Here is the 3500k, 560mm, double-chip version:

https://www.digikey.com/product-detail/en/samsung-semiconductor-inc/SI-B8U521560WW/1510-2222-ND/6624006

8800lm, 171 lm/w, $27 each (much cheaper as quantity increases).

Digikey currently has the 5000k also.

20 bucks apiece in quantity? No thanks.

 

[nogod_]

They are 171lm/w at 50w each strip. 3 of these would shit on a quantum board.

Edit: these are 3500k so not really fair comparison but they still kick ass and imho worth the $$$.

20 bucks apiece in quantity? No thanks.

 

[haze010]

They are 171lm/w at 50w each strip. 3 of these would shit on a quantum board.

Edit: these are 3500k so not really fair comparison but they still kick ass and imho worth the $$$.

At that price the H series is still the better deal.

 

[Sanitas Vibrationum]

They are 171lm/w at 50w each strip. 3 of these would shit on a quantum board.

Edit: these are 3500k so not really fair comparison but they still kick ass and imho worth the $$$.

Actually 2 of these would do that due to exact same amount of chips, but it's a S7 bin and better spread $55 for 2 double strips vs $75 for QB