need some help

[fludunlimited]

I need to know if I can direct drive a Q5 with a 3volt button cell with out burning up the led?
and how long will it last with 2 of them.
http://www.dealextreme.com/details.dx/sku.6999

 

[TigerhawkT3]

You can even drive a 5mm with two 3V button cells in series without killing it (degrade, yes; kill, no). It'll be absolutely no problem driving a Cree off one or two of them.

 

[Lynx_Arc]

you could probably drive a cree with 3 or more of them possibly 5 or 6 in series as they cannot supply enough current to harm it I don't think as a cree Q5 can take an amp or more.

 

[fludunlimited]

cool, thanks

 

[gillestugan]

you could probably drive a cree with 3 or more of them possibly 5 or 6 in series as they cannot supply enough current to harm it I don't think as a cree Q5 can take an amp or more.

Probably no harm to the LED, but certainly harm to the batteries.
Those button cells are made to deliver a few mA and won't last long if you try to push them over their limits.