On Thu, 14 Jan 2010 06:53:35 -0600, John Fields wrote:

On Wed, 13 Jan 2010 19:15:56 -0800, John Larkin
wrote:



If you use 14 volts to run a 3.4 volt LED, with a dissipative system,
the efficiency is always around 24%. Different circuits just move the
heat around.

With pairs of LEDs in series, efficiency becomes 6.8/14 = 48%.

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Yes, but if one fails shorted the second one will follow soon after if
its If(max) is exceeded, while if one fails open two will go out so
you're trading efficiency for reliability.

JF

Seeing as how we are talking of 10 or 20 parallel strings losing 10% or less
of total illumination does not constitute complete failure.