frica
Well-Known Member
Even when underdriven and water cooled the Epistars get destroyed in efficiency unless you cherry pick bins.I wouldnt say the epistar leds are better, but they are definitely cheaper per watt. Its a big hit to efficiency but when cooled very well and underdriven it can reach at least within arms length of the cree cobs at rated power levels. Obviously the same thing done to a cree will do a lot better, but initial cost is very high, and if i would have had a catastrophic failure and destroyed the cobs like i just did to my set i was just using, i would probably have cried a bit lol. Especially for initial testing purposes this was definitely the way to go for me. Of course not many ppl do aquaponics or have a large enough tank to support this amount of cooling, so it wont work for 99% but if someone wants to do it, it can be done.
Besides water cooling will only cool the COB at most a few degrees more than a proper air cooler.
mahiulana claims the Epistar produces 138.2 lm/w at 721mA.
https://www.rollitup.org/t/pictures-of-your-diy-lights-post-your-pics.871625/page-81#post-13439413
It's quite clearly a 5000/5700k light, and Cree COB of similar CRI and colour temp go up to the DD bin.
http://pct.cree.com/dt/index.html
A DD binned CXB3590 at 50W with a junction temp of 105 degrees celcius is still 168.1 lm/w.
That makes the 3590 21.6% more efficient.
But a juntion temp of 105C is very high, even with passive cooling.
A Tj of 85C is much more realistic and puts it at 175 lm/w.
26.6% more efficient.
With a proper air cooler you should be able to get a Tj of 50C.
189 lm/w.
36.7% more efficient.
Electricity costs are much higher than the initial price of the COBs and if a properly cooled 3590 is 36% more efficient then the 30-40 dollar you pay extra is easily earned back.
And there are chips just as good/cheaper than the 3590.
The Luminus CXM22 is only 19 dollar.