From: Vincent Slyngstad: Friday, July 22, 2016 10:39 AM
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.
Vince
