COB efficiency Spreadsheets
- Thread starter nogod_
- Start date
Shig87
Member
did you guys read the first post? wtf happened in that year
just calm down , create a new thread post ur questions there or use google to find ur answers i bet for 100% everything got asked more than 100 times
because of people like you everyone has to look now through 19 sites
just calm down , create a new thread post ur questions there or use google to find ur answers i bet for 100% everything got asked more than 100 times
because of people like you everyone has to look now through 19 sites
frica
Well-Known Member
You don't need to change those values when only looking at led lm led/lmw led/etc.
pop22
Well-Known Member
pop22
Well-Known Member
Using DHL of shipping is like using a pitchfork to shovel wet shit! I'd walk to China before I'd ever use those assholes ever again!
Had an oder come from china in three days! THEN it sat in a wharehouse ( AFTER customs ) for 10 days. After several calls to them, it finally showed up. i told the driver to take it back and tell them to shove it in their ass. EVERY time I've had an order thru them, this shit happens.
I NEVER accept DHL as a shipper, I'd find someone else to buy from if that's their only option.
rant over......
Had an oder come from china in three days! THEN it sat in a wharehouse ( AFTER customs ) for 10 days. After several calls to them, it finally showed up. i told the driver to take it back and tell them to shove it in their ass. EVERY time I've had an order thru them, this shit happens.
I NEVER accept DHL as a shipper, I'd find someone else to buy from if that's their only option.
rant over......
Fastslappy
Well-Known Member
Don't know if I'm too dumb or too high, but I could not find it....
Ok, so i found it here:
https://www.rollitup.org/t/cob-efficiency-spreadsheets.865238/page-13#post-12076428
cheers!
BOBBY_G
Well-Known Member
@SupraSPL :
im trying to derive efficiency equations from PCT to share with the board, but cant match the factors you used in your 3590 spreadsheets.
I always come out with less efficiency.
For example you use the following factors for various currents @ 50C
1.4 0.7133
2.1 0.9733
2.4 1.051
2.8 1.1622
for the life of me i cant match those under PCT
at Tj=50C i get lower efficiencies across the board
1.4 0.661
2.1 0.922
2.4 1.016
2.8 1.125
i have to really do some monkey business with the Tj to get close to your factors. At 16.5C i can get close at the low currents, but the high currents are considerably higher.
1.4 0.713
2.1 0.995
2.4 1.096
2.8 1.214
could you shed some light on how you derived your factors, im surely missing something here. Obviously youre derating 2.1A and above for temperature, but again without a basis i dont know where to start as adjusting the data via Tj is the only trick i have...:
im trying to derive efficiency equations from PCT to share with the board, but cant match the factors you used in your 3590 spreadsheets.
I always come out with less efficiency.
For example you use the following factors for various currents @ 50C
1.4 0.7133
2.1 0.9733
2.4 1.051
2.8 1.1622
for the life of me i cant match those under PCT
at Tj=50C i get lower efficiencies across the board
1.4 0.661
2.1 0.922
2.4 1.016
2.8 1.125
i have to really do some monkey business with the Tj to get close to your factors. At 16.5C i can get close at the low currents, but the high currents are considerably higher.
1.4 0.713
2.1 0.995
2.4 1.096
2.8 1.214
could you shed some light on how you derived your factors, im surely missing something here. Obviously youre derating 2.1A and above for temperature, but again without a basis i dont know where to start as adjusting the data via Tj is the only trick i have...:
BOBBY_G
Well-Known Member
aha! is this it?:
https://www.rollitup.org/t/cob-efficiency-spreadsheets.865238/page-6#post-11694581
(combined current and temp droop)
surprised PCT doesnt correct for this with reasonable accuracy
1)why do you state 50C and use Tc=25 in charts? is there a rule of thumb for equating Tj and Tc?
2) assuming you extrapolated the 55,60,65C Tc temps from pixel counting on the curve?
best fit i can get on PCT is to use your stated assumed Tj - xx degrees, then the curve is close
so for example you show
1.4 0.7133 (50C Tj)
2.1 0.9733 (60C Tj)
2.4 1.051 (65C Tj)
2.8 1.1622 (65C Tj)
3.6 1.3354 (70C Tj)
using Tc=Tj-35 I get from PCT:
1.4 (15C Tc) 0.715
2.1 (25C Tc) 0.977
2.4 (30C Tc) 1.064
2.8 (30C Tc) 1.178
3.6 (35C Tc) 1.348
using Tc=Tj-30 I get from PCT:
1.4 (20C Tc) 0.707
2.1 (30C Tc) 0.966
2.4 (35C Tc) 1.052
2.8 (35C Tc) 1.165
3.6 (40C Tc) 1.333
pretty close......it seems Tc and Tj is interchangeable for COBs, the PCT calls it Tj but I think thats just a legacy designation within the tool, since there are all the single dies in the PCT which still use Tj. Furtehrmore the PCT Tj data it seems to match the Tc data from the chart in the datasheet, and the datasheet also explains that Tj is obsolete as a field measurement for COBs
thanks
https://www.rollitup.org/t/cob-efficiency-spreadsheets.865238/page-6#post-11694581
(combined current and temp droop)
surprised PCT doesnt correct for this with reasonable accuracy
1)why do you state 50C and use Tc=25 in charts? is there a rule of thumb for equating Tj and Tc?
2) assuming you extrapolated the 55,60,65C Tc temps from pixel counting on the curve?
best fit i can get on PCT is to use your stated assumed Tj - xx degrees, then the curve is close
so for example you show
1.4 0.7133 (50C Tj)
2.1 0.9733 (60C Tj)
2.4 1.051 (65C Tj)
2.8 1.1622 (65C Tj)
3.6 1.3354 (70C Tj)
using Tc=Tj-35 I get from PCT:
1.4 (15C Tc) 0.715
2.1 (25C Tc) 0.977
2.4 (30C Tc) 1.064
2.8 (30C Tc) 1.178
3.6 (35C Tc) 1.348
using Tc=Tj-30 I get from PCT:
1.4 (20C Tc) 0.707
2.1 (30C Tc) 0.966
2.4 (35C Tc) 1.052
2.8 (35C Tc) 1.165
3.6 (40C Tc) 1.333
pretty close......it seems Tc and Tj is interchangeable for COBs, the PCT calls it Tj but I think thats just a legacy designation within the tool, since there are all the single dies in the PCT which still use Tj. Furtehrmore the PCT Tj data it seems to match the Tc data from the chart in the datasheet, and the datasheet also explains that Tj is obsolete as a field measurement for COBs
thanks
Last edited:
Getgrowingson
Well-Known Member
Yea they are real useless toits that's for sure. Slow as he'll and could care less about you or your package
sixstring2112
Well-Known Member
Lots of great info in this thread,wanted to post so i can find it later.and why is this one not stickied yet?
Supra can you help me work out how much umol my light would have?
I'm planning 16 CXB3590 36V 3500K CD bin per m2 running at 700ma, in the graph it says 2.98umols per watt but in a another thread I see you multiply the PAR watts by 4.88, I don't under stand.
captainmorgan
Well-Known Member
You would have about 1000 PPFD.
klx
Well-Known Member
Around 980 ppfd. Use this to try out different configs - http://rollitup.org/t/diy-cob-led-calculator.890214/
EfficientWatt
Well-Known Member
Yes, in PCT Tj is actually Tc.
PCT gives you the min value, supra uses average value. To do this, for CD bin, you'd need to take the average of CD and DB. ( (CD+DB)/2 but you know how to work out an average
)
Hope this helps.
PCT gives you the min value, supra uses average value. To do this, for CD bin, you'd need to take the average of CD and DB. ( (CD+DB)/2 but you know how to work out an average
) Hope this helps.