by Bill C. for webBikeWorld
My flashlight obsession has most of my family thinking that
I'm slightly off kilter. I always carry one on the bike, and I also
make sure that there are at least two next to me before I go to sleep.
The truth is that my night vision is so bad that I'd be
completely helpless without a flashlight if the bike stalled at night,
especially in the deep darkness that covers our rural county after sundown.
But there's a problem: the batteries always seem to be in one
of two states: dead or dying. Flashlights are great in an emergency,
but only if they work when the switch is thrown!
That's why I became curious about the new "shake
flashlights" that have recently been made available to consumers. The
advertisements seem too good to be true: shake the light a few times
and you'll be blessed with eternal light.
We purchased the NightStar version shown here, which is a
"full size" flashlight, about equivalent in size and heft to a double D-cell
standard flashlight. Note that the technology for these products is
rapidly evolving, and there are smaller flashlights now available.
But there aren't any that I've found that are as tough as
this one, as you will see.
The manufacturer claims that the NightStar
requires "no batteries, no bulbs, no maintenance...ever!", which definitely
piqued our interest as a motorcycle flashlight solution.
All of these shake flashlights operate on the same
principle, more or less.
If I had paid attention in high school physics, I'd be able
to tell you what that principle is. I think it has something to do
with a magnet passing through a coil of wire, which creates electricity.
Wasn't Faraday the chap who discovered this effect, back in the early
A shake flashlight has a fixed coil of wire, usually in the handle (see
Photo 2), and a moveable magnet that passes through the coil. By
shaking the flashlight back and forth, the magnet passes through the coil
and creates electricity. The electricity is stored in a capacitor,
which becomes charged. This is enough to power the LED bulb and
The body of the NightStar II Clear Magnetic Force model that
we purchased is made from a clear, heavy-duty plastic of some sort.
The manufacturer claims to have the
patent on the "original shake light".
The body is apparently
sealed for life; I can find no way to open the tube to change the bulb,
which I assume probably will never need changing anyway, since it's a single
LED. The flashlight weighs 11.125 ounces, or 315 grams.
It's exactly 10" long (25.5 cm), and the handle is 1-7/16" in diameter
at the handle (~33 mm) and 2" at the head (~51 mm).
There are warnings on the flashlight and in the owner's
manual about the strong magnetic field that surrounds this flashlight, and
they aren't kidding -- I can't place a steel tape measure anywhere near the
thing without it getting instantly attracted to the flashlight.
it's important to be careful about using or storing this type of light near
any materials that might be affected by a magnetic field, such as a computer
floppy disk. I had no idea that the field around a shake flashlight
would be so strong, and this is a definite downside to using this type of
Just in case you get lost, the instructions claim that the
NightStar can be hung by a string, and it will automatically indicate north
and south, just like a compass, with the light always pointing north.
The "glow in the dark" on/off switch on the NightStar looks
to be completely unconnected to the circuitry; that is, I can see no wires
or anything that might indicate how the switch actually makes the light turn
on and off. But somehow the switch does indeed turn the light on and
off, so this remains a mystery.
The manufacturer claims that the
switch will glow for several hours after only 10 minutes of direct exposure
to sunlight or room light.
The switch does not look waterproof to me, which is another
mystery, but the instruction booklet claims that the NightStar can be used
to a depth of 430 feet (131 meters), and has a crush point of 180 pounds per
square inch. That must account for the weight of the light and the
thickness of the clear plastic body. 430 feet is definitely
waterproof, I'd say. This is a plus for the NightStar.
The manufacturer also claims that the light can be
"repeatedly" dropped from a height of 4 feet (1.2 meters) with no problems.
And in case you were wondering, they also claim that it will remain
operational "after three days immersion in solutions of salt, water,
isopropyl alcohol, methanol, bleach, ammonia, and acetic and phosphoric acid
(10% solutions). This is one tough flashlight!
It also carries a 5 year warranty. If the light fails
within 5 years, they will replace it for free. They must have a lot of
faith in the NightStar for sure.
The NightStar is charged from empty by shaking it back and
forth for about 3 minutes at 2-3 times per second. The light must be
held parallel to the ground and the magnet must pass completely back and
forth through the coil. It sort of has a spring effect, I think due to
the sealed chamber, which doesn't let any air escape. The air acts as
a cushion at either end of the shake.
If the flashlight is partially charged, it takes about 90
shakes to bring it back to full power. Full power is a bit less than
what I expected, but it's about as much power as one can get out of a single
It's adequate, but don't expect the same brilliance as you'd get
from, say, a two or three D-cell halogen flashlight like a Mag-Lite.
The manufacturer claims that the NightStar's beam has a 5 foot diameter at
50 feet, with an effective range of "50 feet non-reflective and 150+ feet
reflective, visible from over 1 nautical mile away".
The combination of an incredibly tough body and ultra-waterproof performance
makes the NightStar hard to beat as a flashlight that may bounce around in
the saddlebags for years before it's actually used. If you can live
with the strong magnetic field that surrounds the light at all times, and
you don't mind the size, this one's a keeper.