overvolting led's

[kernman]

can you overvolt an led say by using lithium ion vs nimh.....thanks much

 

[MikeLip]

You can overCURRENT an LED. Voltage on the LED is fixed by Vf - the voltage drop across the device when conducting in the forward direction (which is its normal operating regime), which is fixed over a wide range of currents.

If your current regulation scheme is a simple one such as a series resistor, then yes you can. If it's more complicated like a regulating supply, then the answer is also more complicated and depends on the design of the regulator.

 

[kernman]

Thanks mike...so I can use lithium ions in my black diamond Icon that I'm guessing just uses a resistor? The Icon uses 3 AA and right now I'm using NIMH..........thanks

 

[MikeLip]

I suspect so. LiIon has a terminal voltage of 1.5, as does alkaline. So a simple series resistor should be OK unless the drain is so high that the terminal voltage of the alkaline is severely dropped.

 

[Marduke]

I suspect so. LiIon has a terminal voltage of 1.5, as does alkaline. So a simple series resistor should be OK unless the drain is so high that the terminal voltage of the alkaline is severely dropped.

Lithium Ion is 3.7v, lithium manganese dioxide (ie. e2 lithiums) is 1.7ish new, 1.5v nominal.

 

[MikeLip]

Lithium Ion is 3.7v, lithium manganese dioxide (ie. e2 lithiums) is 1.7ish new, 1.5v nominal.

You're right - my error! I shouldn't post when I'm on migraine meds!

 

[Fallingwater]

If you substitute one LiIon cell to the three NiMH you're using now, it'll probably work. If you use three LiIon cells (say, AA-sized 14500s) instead you'll probably blow the emitters or the regulator.

 

[scott.cr]

Thanks mike...so I can use lithium ions in my black diamond Icon that I'm guessing just uses a resistor?

You should find out for certain if it uses a resistor. If it uses a constant-current converter, too much voltage will probably burn it out.