Batteryless Flashlights?

[Richard P.]

I saw a product at a local mall a few months ago and I saw it again tonight, it's a flashlight that
doesn't need batteries. You just shake it back and forth for 30 seconds and you get about 20 mins
of light from it. It has a couple of white LED's and the case is clear allowing you to see the
magnet that slides back and forth inside a coil of copper wire as you shake it.

Anyone have any real world experience with these..?

 

[Anthony Matonak]

I saw a product at a local mall a few months ago and I saw it again tonight, it's a flashlight that
doesn't need batteries. You just shake it back and forth for 30 seconds and you get about 20 mins
of light from it. It has a couple of white LED's and the case is clear allowing you to see the
magnet that slides back and forth inside a coil of copper wire as you shake it.

Anyone have any real world experience with these..?

I've played with a few of them. They use a high power magnet sliding
through a coil as you shake it to generate power. This power gets stored
in a small capacitor. Often they suggest you turn the switch off when
shaking it for charging. If you don't turn off the switch you can watch
the LEDs pulse with the power spikes coming from the coil.

They take a lot of shaking and they only produce useful light for a
few times longer than you shake it. You wind up pausing every 20 or
30 seconds to give it a few more shakes. They're main advantage is
that they can be stored for long periods of time without worry about
leaking batteries. Unfortunately, they're only really bright enough
to light your way to finding a regular flashlight and batteries for
it.

Personally, I think a better design would be to use this technology to
update the old squeeze/crank flashlights. Using similar high powered
magnets, power management circuitry and LED's these old squeeze lights
could actually be practical.

One note, they use VERY strong magnets. Do not place them near credit
cards. On a brighter note, you can usually hang them on your fridge.

Anthony

 

[Gordon Richmond]

I have no experience with the one you describe.

I have a "no battery" flashlight, with built-in FM radio, no less,
that was a safety award from work. It has a little fold-out crank, and
you wind on it for a while, and then you can use the light or play the
radio. Kind of gimmicky, IMHO, but it does work. I keep it in the
truck, for emergency use.

It's not a new idea. Dynamo flashlights have been around since the
late 1940's at least. I remember my father having one; a small
Bakelite cae with a handle that you squeezed... Squeezing the handle
caused a sector gear to move, spinning a tiny pinion gear, which drove
a PM dynamo. Eventually, continued use would wear the teeth off the
sector gear.

Using one of these will give a person an appreciation of just how much
"work" goes in to making a useful light source.

Gordon Richmond

 

[William P.N. Smith]

I saw a product at a local mall a few months ago and I saw it again tonight, it's a flashlight that
doesn't need batteries. You just shake it back and forth for 30 seconds and you get about 20 mins
of light from it. It has a couple of white LED's and the case is clear allowing you to see the
magnet that slides back and forth inside a coil of copper wire as you shake it.

Yeah, I've got a small one that a friend gave me, and while it's a
neat toy, it's not much of a flashlight. I dunno who specified the 30
seconds gives you 20 minutes, but IME they've got their numbers
reversed...

 

[wmbjk]

Yeah, I've got a small one that a friend gave me, and while it's a
neat toy, it's not much of a flashlight. I dunno who specified the 30
seconds gives you 20 minutes, but IME they've got their numbers
reversed...

In other words... if it's midnight and you need ten minutes of light,
it might be quicker to wait for the sun to come up.

Wayne

 

[Gymy Bob]

The new ones are LEDs and take very little power. The older units were
incandescent bulbs and make the poor timing truer.

 

[Heywood Jablome]

I've got two of them. The ones I have are single led. It gives you
light in the dark, but it doesn't have the output a battery powered
led light does. When you shake them you are charging a super
capacitor. The are okay as an emergency light in that no batteries to
be concerned with.

We haven't used them will camping yet, so my real world is limited.

I was surprised at how long the cap held a charge with the led off.

Oh, and the ones I have are 'sposed ta' float. Haven't tested that either.

--

yes they should be water tight. I had a play with one today and even the
switch was actually a reed switch which did not need a hole in the case. The
only water point of entry would be where the lens is, but that had a rubber
grommet around it. It would be good for water sports.

 

[lost soul]

Hey are you the guy that was on slimdogs a couple years ago?

"Heywood Jablome" <reply to thread> wrote....

 

[Heywood Jablome]

Hey are you the guy that was on slimdogs a couple years ago?

Nope. Not me. What's slimdogs?
-H