Hi Lindy,

just be aware that some manufacturers sacrifice longevity for initial
brightness

For example, the individual "safe" data sheet voltages of LEDs in a
string may total < 12V and so would be over-driven with 12V supply

And Vf rises with frequency, so red < green < blue. If there were say
3 strings made up of 6 LEDs of each colour, without any current
control, then the red string could be over-driven and the blue string
under-driven

It's quite common for example in white LED torches to include no
series resistor and rely on the impedance of the battery to do the
current limiting. That does mean though that for some time the LED(s)
will be detrimentally over-driven

To get the best life out of your strings it would be best to measure
the LEDs' Vfs at a particular current and work out either a series
resistance for each string or a % PWM which will average to the
correct power level

Joe



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