22 Jul
2016
22 Jul
'16
7:18 p.m.
On 2016-Jul-22, at 11:00 AM, Vincent Slyngstad wrote:
From: Vincent Slyngstad: Friday, July 22, 2016 10:39
AM
Nice to see the data & math on that.
Somewhere, I have Oshino's write-up about
bulb rated voltage and bulb operating voltage, but I do remember the lifespan varies as
some power of the ratio, and it makes a huge difference. (There are also formulae for
derating brightness, etc.)
I found it -- the lifespan varies as the 12th power of the ratio.
The current varies as the 0.55 power, and the brightness as the 3.5th power (of the
reciprocal).
So, a 12V bulb in a 28V circuit can expect 1/26000 the lifetime, and will take about 1.6X
the current to burn about 20X brighter than normal.
A 28V bulb in a 24V circuit would last about 6.3X it's rated lifetime, take 92% of
the rated current, and about 58% as bright.