i am looking to build a diy led setup for my 125g long, i was going to buy some 50 watt led outdoor floodlights from amazon till i herd the reviews on most of them. i found a score of 50x3 watt 10000k cree style leds. FV is 3.2-3.6v, and FC is 750mA. either i am super tired or just not looking in the right places, but i can not find a driver to run them. i also believe my math is wrong to. if each led needs up to 750mA and i have 50 of them i would need 37.5 amps(dont sound right). i am trying to do this with as few drivers as possible, 1 is best. thanks in advance
volts add in series... amps add in parallel
10 Crees connected +...-...+...-...+...-..ect.. needs 32-36v and you can drive them at 750mA
Connecting 5 of these in parallel you still only need 36v but now you need 3.75A.
So that would be the spec of a single driver...oh and power dissipation of 150W (generally add 10% safety margin)
"in theory" this is all you need, once you adj. the current to 3.75.. More of a "constant voltage" driver w/ constant current properties.. CLG-150-36
http://www.meanwell.com/search/CLG-150/CLG-150-spec.pdf
and cost would be $55 or so and no dimming.
AGAIN I'm not guaranteeing this nor recommending a 1 driver approach for 50 LED's
Parallel strings has some design "issues"...that make them not as desirable as all in series..
For example if one of the 5 fails "open" then the current gets re-proportioned instead of 3.75/5 it becomes 3.75/4.. another fails and it becomes 3.75/3 =1250mA going into the final 3 strings and most likely burning them all out or, at the least, shortening their lifespan..
Another one: "not all strings" will be equal so you can have visual mismatches between strings.
a more reasonable approach would be using LDD-700's and 5 of them @ $7 each.. ($35) and 5 individual series strings
Coupled to a 36V power supply (3.75A, 150w+) @$30 IDEALLY your PS should be 3 V over what you require. Driver loses 3v so it should be 39V..but that is another subject and to be honest your total V(f) will probably not be 3.6v x5
Your MINIMUM voltage for 10 in series is 32v plus 3v (35V) if using a ps driver combo.
That aside and the added parts count, pricing is close to the same and if you choose, each channel is dimmable separately..
to up the "specs" to fit the above more closely, just make the strings 9 LED's each x5.. Still plenty of light. (9x3.6=32.4v +3 = 35.4 )
