resistored series led questions

[aljsk8]

A little dumb question

i really should know this by now but... well i dont

i have a SLA battery 12v (around 13v when its fully charged)

i run 3 cree on a computer heatsink with a fan (also run off the battery)
its a resistored setup cant remember the resistor

without the fan it runs hot which says to me that energy is wasted
also the leds are probably at 1200ma or something stupid - so not running at an "efficient" current

if i use more leds but the same SLA battery will i get more light?
my calculations says no but i cant seam to understand why

from calculation - probably getting 400 lumens from 4 leds
but 700+ from 3 leds

am i doing this right?

its a light for my outside shed incase you were interested

at what point are you wasting so much energy (heat and bad efficiency of leds) where using a halogen bulb would be as bright and as efficient

thanks

Alex

 

[Lynx_Arc]

The crees will be more efficient than the halogen even though there is heat given off that is just because LEDs are not 100% efficient. If they are wired in series the resistor ir probably the most cost effective efficeicnt way to do so. I would however consider getting a larger heatsink that a fan isn't needed as that is killing your efficiency a lot. running the LEDs at less current will incread the efficiency also if you do not need as much light the 4LED setup if bright enough may not require a fan and also be more efficient at the light they output too.