Difference between AA Alk's and Lith's?

[junior]

Difference between AA Alk\'s and Lith\'s?

Is there really any difference between AA alkalines and AA lithiums? And if so, what are the differences.

The reason why I ask is that i put a 5mm led in my mini-mag and it is not that bright. Would it be worth it to purchase AA lithiums? Do you think the liths would add to the brightness? and if so how much?


What say you?

 

[andrewwynn]

Re: Difference between AA Alk\'s and Lith\'s?

there was a big thread on AAAs with the same question.

the AA lithiums do not have considerably more voltage so they won't be much brighter.. they may last longer, and they can handle low temps better... they have a much better shelf life.. those are the main benefits.. LiON AA on the other hand.. 3.7V.. you can make mega mega bright, but that's a different project completely.

 

[Steelwolf]

Re: Difference between AA Alk\'s and Lith\'s?

What colour of 5mm LED did you put in? White LEDs require about 3.6V to reach full brightness. Actually, it requires 20mA to 30mA and that occurs with a voltage of 3.6V. Red, and possibly amber, require less voltage (like about 2V), so those will work in you Mag.

So 2 AA cells will not cut it for white. It will start off dim and only get worse. Your best bet is to use some sort of converter. For example, the Opalec NewBeam, sandwiches from The Sandwich Shoppe, etc. These will take the 3V presented by the 2 AA cells and boost it up to something useable by the LEDs.

To specifically answer your question:
Lithium cells have great shelf life (70% capacity remaining at 10yrs compared to 70% at 4 yrs for alkalines).

Lithiums handle high current demands better than alkalines. ie they have very low internal resistance.

Lithiums are less likely to leak. I have not heard of anyone complaining about leaking lithiums yet.

Lithiums tend to have a flatter discharge curve under heavy loads, as compared to alkalines. ie under a high current drain, you will see the voltage of the alkaline cell fall throughout the entire operation. Lithiums will not have such a dramatic drop in voltage until near the end of its life.

Lithium AAs, designated L91 by Energizer, have similar nominal voltage to alkaline AAs, ie 1.5V, though it might start out just a little higher at 1.7V

That's all I can think of right now.

Check out the converters I mentioned. Check out Elektrolumens; he has one too. And the Terra-Lux, I think that's the correct name. Yeah, quite a few available.