Em 29/2/2012 11:50, alan.b.pearce@stfc.ac.uk escreveu:
> I have an LED torch that gets its power from being wound up. It has died,=
 and now won't charge up by winding, well winding produces voltage, but it =
won't retain charge. Had a look inside it, the generator produces about 12V=
 when wound, but the capacitor looking piece immediately drops back to abou=
t 3V when you stop winding.
>
> Does anyone know what is used for energy storage in these? The device in =
it looks like a capacitor, marked=20
>
> 3.6V 80mAh
> 12hr 8ma
>
> >From the way the voltage across it drops back to almost nothing I'm gues=
sing it has gone AWOL.


The "mAh" rating is used for batteries.

Perhaps a LiFePo4 battery (lithium-iron-phosphate). They are rated at
3.3V per cell, the open circuit voltage is about 3.2V and the max.
charging voltage is 3.6V.
Or a LiPo (lithium-polymer). They are rated at 3.7V per cell with a max.
charging voltage of 4.2V


Best regards,

Isaac

--=20
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