Re: Battery/lighting philosophy for fully-loaded touring?

On Apr 15, 5:13 am, Ben C <spams...@xxxxxxxxx> wrote:


I think I could probably see OK with a 3W light in the dark (I use a
cheap but effective lead-acid system with 12W altogether, but with only
one of the lights on it's 6W and that's still quite bright).

Of course, it's not just the wattage that matters.

I recall when my best friend bought a 10 watt rechargeable set from a
well-known mail order company. This was many years ago. Good sized
separate battery on a curly power cord, professional looking headlamp
housing, nice mounting - and almost useless. It didn't come close to
the usability of my standard generator light, because the optics were
so terrible. That 10 watts was sprayed all over creation, not
directed onto the road. Optics makes a huge difference.

Another factor, for incandescent (including halogen) bulbs is the
designed bulb life. Two incandescent bulbs of equivalent wattage can
put out very different numbers of lumens (that is, total light
output). In general, bulbs designed for longer life put out less
lumens per watt; bulbs designed for more lumens per watt don't last as
long. Bike headlight bulbs don't accumulate nearly as many hours as,
say, lights used for ornamental track lighting (the MR-11 bulbs at
your hardware store). So dedicated bike bulbs can and should be
designed for relatively short lives, to allow more light output from
the same wattage.

The optics and the bike-specific bulb design are two reasons a three
watt generator lamp does much better than many people think.

Carrying the wattage idea a bit further, it's obvious that the lumen
per watt ratio of LEDs has completely different constraints. There's
lots of intense research in this direction, and there's little doubt
we'll all end up with LED lights someday. But there's a fair amount
of hype, too.

Just the other day, a friend of mine showed me a couple LED
flashlights he bought. He was marveling at the brightness, and
planned to use them for his night commute. He was sure they'd be
wonderful.

For comparison, I brought in the Cateye Micro II halogen light I keep
as a loaner, plus an old 6 watt rechargeable headlight I used to use.
Even the Cateye (2.4 watt, four AA batteries) absolutely blew away his
brightest LED flashlight. And it probably cost 1/3 as much.

Overall, watts are only a small part of the story. More is not
necessarily better. Optics are critical. Mounting position makes a
huge difference too, as others have explained. When people say "You
can't see well enough with just three watts" they're likely comparing
apples and oranges - or maybe watermelons.

- Frank Krygowski

.

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