LED "shaker" Flashlight- buyer beware

[ian]

Got one of these LED "shaker" flashlights for Christmas. I thought it was the coolest thing. It has a coil and some electronics in it for "generating" power for lighting the LED.

BUT............
Upon taking it home and taking a good look at it I see 2 coin cells in amongst the "electronics". I left it on and it shone for about 24 hours, after that....... well the light is very dim now and no shaking makes it brighter, while shaking it only.

[jollyrgr]

There are numerous models of these things. I have two styles that are crank models. I just bought four for my family members this Christmas. All will eventually go dead. You then crank the light (with the light OFF) for about a minute and get 10 or so minutes of useful light. Cranking with the light on will cause the light to come on but it will not charge. Turning the light off and cranking for a minute will recharge the thing so it will light continuously.

Are you shutting the light off when you shake it up? I'm guessing there are some designs with coin cells. Most I've seen have a one farad capacitor as the storage source. The "Freecharge" by Motorola and Freeplay use NiMH batteries. As do some of the similiar knock offs.

I stated that I had two styles of crank flashlights. One style uses the capacitor. I can crank for about a minute and get very bright light from one LED for about 20 minutes. If I use all three LEDs it lasts about 10. The other style I have is about the size of a pager and has batteries. It also has a DC output for powering cell phones or other electronics. Although much cheaper in construction this light is much brighter and can have either one, two, four or five LEDs on at a time. I cranked it up for two minutes about three months ago and it is still working at full brightness with intermittent use.

With that long winded statement out of the way, I have to ask; what version did you get? Linen N Things had some shake lights for sale this Christmas season. But by the time I made it there, they were sold out. A friend got some and likes his. What brand did you get?

[Rodney]

ian, I took one of those apart also. Contains two 3 volt LiIon button cells in series with a small resistor (6.8 ohm approx.)in series with a white LED then to a switch. There is no connection between the apparent coil of wire that the metal slug passes thru as you shake it, a complete farce as to the shaking doing any good. When the button cells run down, the light is out for good or until replacement of the batteries. Mine was still a good buy, could not have bought the two cells for the price I paid for the entire thing.

[dacflyer]

i bought the same BS too.. i go them from a flea market here,,go figgure.. i knew it was too good to be true..anyway as you all have already said..they are fakes !
metal slug and dummy coil and no electronics in them,,its more of a masturbater flashlight..
i took mine back and demanded my money back, or i would report the vender as selling fraud stuff..
he was pissed, but i got my money back,,and i still told the flea maeket manager..didn;t see the stuff on his table last week,,Hmmm wonder if he sold the rest or deleted them,,
they did give good light otherwise,,but i wanted them to work as told too....

[Chris Smith]

In the good ones they are super caps, not batteries. I prefere to build them my self, including a solar version that charges all year, until you actually need it.

[jollyrgr]

What "brand" or vendor sold this fake one? Was it an AS ON TV product, a "dollar store" close out, or a big chain department store version?

[haklesup]

Rodney, the connection between the metal slug and the coil is the magnetic field produced by the slug which is in fact a magnet. The configuration is of a linear motor working as a generator. I would assume there is a diode somewhere in series with the coil and battery in the shaker models (but not necessarily the crank models) as you would charge on the way up and discharge on the way down.

All of these need some sort of storage component. It may be that the LiIon batteries are no longer capable of recieving a full charge due to deep discharge or maybe they were cheap batteries to begin with. You may need to charge it considerably before you are back up in the nearly charged range where it was presumably designed to work

It is my understanding that these are intended as emergency lights that may be stored for very long times before use as opposed to continuous or long term use.

It seems analogous to the cold heat soldering iron. Works great in a narrow range of specific applications but is not so great for general use.

[Rodney]

Hackles up, No these were definately fakes. I'm an electrical engineer with many years experience in failure analysis and electonic design so do know how these things should work. Yes, there are some legitamate units out there but there are also a lot of fakes. The slug in the one I took apart was not even magnetic.

[philba]

Originally posted by Rodney:
Hackles up, No these were definately fakes. I'm an electrical engineer with many years experience in failure analysis and electonic design so do know how these things should work. Yes, there are some legitamate units out there but there are also a lot of fakes. The slug in the one I took apart was not even magnetic.

that so wierd, the cost of building a real one can't be much more than a fake.

[haklesup]

Maybe it used to be a really cheap magnet that got demagnitized somehow. Without a magnetic field line cutting across a wire, you can't induce a current using the generator effect. I have never seen a piezo-electric generator but that would be cool.


By "Fakes" I assume you mean cheap knockoffs not non functional replicas.

[dacflyer]

haklesup >> the slug is definatly, never been magnatized,,also the coil wires were never connected inside..just tack solidered to a spot on a blank circuit board..

[jollyrgr]

Brand?

Where Purchased?

Identifying Traits?



This would help others avoid making the same mistake. Besides, I'd like to see one of the fakes for myself.

[dacflyer]

jolly rodger , i can send you fotos of the ones i had,, whats a insult to me is,,they they have the
"das grune punkt" logo on it,, which tells me its MFG, in Germany...i highly doubt my people would ever stoop so low to make such a thing..
as for brand name..i will have to look again..
as for where i bought it... flea market..
now i have seen them also sold at cracker barrel
for like 19.95 and they were real,,
gimme a e-mail, and i will send you dome detailed fotos,, and maybe you can post them here,, i have no way to post them,,

[Rodney]

My findings were the same as dacflyers. The coil wires unterminated, in my case just taped down to coil form with no attempt to terminate them. The only component on the printed circuit board was the LED and an unmarked 6.8 ohm resistor between the LED and the two Lithium cells. Mine was also purchased at a flea market for less money than I'd have to pay for just the two Lithium cells so I figure I at least got my moneys worth.