On 02/04/2014 11:59, John Fields wrote:
On Tue, 1 Apr 2014 18:39:27 -0500, "Maynard A. Philbrook Jr."
wrote:

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Look at all the sims I've posted - or even just one - and it should
be apparent, even to you, that you're talking out of your ass.
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Did you figure out that bloggs screw up yet?

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Here's his post:

"The apparent battery capacity increases dramatically at lower drain
rates. So if you want to increase battery life beyond belief, the
thing to do is wire the LEDs in series and then use a "boost"
converter to step-up the 6V voltage to 24-30 V as required."

Where's the screw-up?

John Fields

It does work as advertised - his claim is not at all believable.

Putting red LEDs in pairs with a basic resistor ballast hung off 6v will
easily match or beat his suggested method. The buck converter on that
step up ratio would be lucky to get 80% efficiency and is a lot more
complex to implement.

PWM regulating of the current would be another choice. The losses could
then be as low as Vsat.Imax plus dissipation in a smaller series
resistor to ensure chains share current more or less equally.

Most LEDs can survive a higher pulsed current provided that their power
dissipation is not exceeded. More of your supply voltage gets converted
into light this way since Vf rises with increasing current.

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Regards,
Martin Brown